Necrosuppurative Mastitis in a Sprague Dawley Rat Following a

Necrosuppurative Mastitis in a Sprague Dawley Rat Following a

Necrosuppurative Mastitis in a Sprague Dawley Rat Following a 

Prematurely Weaned Litter 

Andreanna Pavan, Carrie Freed

University Laboratory Animal Resources


Mastitis is a bacterial infection that forms in the mammary gland causing inflammation, redness, and pain to the affected tissue.

Predisposing factors for the development of mastitis include mammary gland congestion, trauma, and poor sanitary conditions. It can develop in breeding females of any species.

Only two cases of spontaneous mastitis been reported in the laboratory rat.

One report (1995) identified Granulomatous dermatitis due to S. aureus in two Sprague Dawley rats and the other (1978) identified chronic necrotizing mastitis in F344 rats caused by Pasteurella pneumotropica.


Laboratory rats used in biomedical research require strict sanitation frequencies which may decrease the likelihood of bacterial invasion following trauma. We diagnosed an isolated case of mastitis in a breeding female

Sprague Dawley following removal and use of the pups prior to weaning.

Clinical Presentation:

A 5-mo-old breeding female Sprague Dawley rat presented with vaginal discharge, piloerection, hunched posture, and porphyrin staining at the external nares and left eye. The dam had given birth

17 days prior to presentation, but the litter had been euthanized at post natal day 2 for study purposes.

At the time of presentation, the dam was single-housed in a microisolator cage on a ventilated rack.

Corn cob bedding was available and the cage was changed weekly, with ad lib access to reverse osmosis water and standard rodent chow.

Physical Exam Findings:

• Two firm abnormal shaped masses were appreciated on palpation; one in the left lateral cervical mammary gland (A) and one in right inguinal mammary gland (B) (Figure 1, 3)

• The 1 st cervical mammary papilla on the left, appeared dark in color.

(Figure 2)

Gross Findings:


Figure 1

Figure 4


Figure 2


The rat was humanely euthanized via CO2 inhalation and tissues were submitted for histology. The mammary masses were isolated during necropsy.(Figure 3)


Figure 3

Figure 4: Skeletal muscle on the left, a band of necrotic neutrophils in the middle and necrotic mammary alveoli on the right containing milk and cocci.

Figure 5: Mammary tissue on left, with necrotic and inflammatory debris, and cocci in the middle on the right.

Figure 5


The morbidity of the rat can be attributed to the necrosuppurative mastitis, associated with a large population of gram positive cocci .

Histologic findings were consistent with either a Staphylococcus

aureus or Streptococcus pneumonia infection.

The plasmacytosis noted in a regional lymph node is consistent with chronic antigenic stimulation.

S. aureus is commonly found on the skin and is frequently identified in cases of mastitis due to ease of entry through a crack or lesion in the epidermis


. Such lesions have been reported in ferrets when the kits are at weaning age due to tissue damage from the newly erupted teeth ¹. In this case however, the pups were removed before the incisors had erupted. The early weaning of the offspring can be considered a factor resulting in mammary gland congestion.

The resultant discomfort may have placed this rat at risk for self injury providing an entry point for surface bacteria on the dermis to invade the mammary tissue.

Treatment regiments should include administration of a broad spectrum antibiotic and supportive therapy such as fluids and antiinflammatory drugs¹. Clinical signs may include tissue erythema, inflammation, pain, and discoloration of the mammary tissue.

Early detection of mastitis may allow for effective treatment of this unusual condition for female rats who are part of a valuable breeding colony.

References/ Acknowledgements:

1. Fox J, Anderson L, Loew F, Quimby F. Laboratory Animal Medicine. 2 nd ed. San Diego (CA):           

Academic  Press

2.  Hong C, Ediger R. Chronic Necrotizing Mastitis in Rats Caused by Pasteurella Pneumotropica

Laboratory Animal Sciences. 1978; 28 (3): 317‐320 

3.  Kahn C, Line S. The Merck Veterinary Manual. 9 th ed. Philadelphia (PA): National Publishing, Inc.

4.  Kunstyr I, Ernst H, Lenz W. Granulomatous Dermatitis and Mastitis in Two SPF Rats Associated with  a Slowly Growing Staphylococcus Aureus – A Case Report. Laboratory Animals. 1995; 29: 177‐179


Dr. Pu Duan, Assistant Professor in the lab of 

Dr. Jianjie Ma, Professor

The College of Medicine and Public Health

The Ohio State University


A 23 month-old male Nile grass rat (Arvicanthis niloticus) used in a diet manipulation study was found laterally recumbent and dyspneic. Limited to no response was observed when the animal was handled. Physical exam revealed moderate dehydration and hypothermia and the animal had a body condition score of 2 out of 5. The diet manipulation study assessing the effect of timed food availability (12-hr access during normal active phase) started the previous day and this animal had been exposed to only one 12-hr period of food withdrawal. The animal had appeared bright, alert, and responsive 5 hours prior when food had been replaced by research personnel.

Hepatocellular carcinoma in a Nile grass rat

(Arvicanthis niloticus)

Christian C. Hofer


, Brad N. Bolon


, Dondrae J. Coble


University Laboratory Animal Resources


& Department of Veterinary Biosciences



Figure 2: The large mass was a hepatocellular carcinoma. While tumor cells were well

‐differentiated, its malignant nature of the neoplasm is affirmed by the loss of normal hepatic cords (which are approximately two hepatocytes thick) and arrangement of portal triads and central veins. The arrows denote mitotic figures. H&E, 200x.


The Nile grass rat (Arvicanthis niloticus) is a USDAregulated species that is increasingly used as a research animal model. Nile grass rats are diurnal rodents used investigate a variety of research problems ranging from spontaneous metabolic syndrome to retinal diseases. Most grass rats maintained in captivity with free-choice standard rodent chow will spontaneously develop dyslipidemia and hyperglycemia by 1 year of age. This trait makes the grass rat an ideal species to assess the etiology and pathophysiology of “metabolic syndrome”, which currently affects over a quarter of the human population in developing countries 1 .

Hepatocellular carcinoma (HCC) is a major human health problem worldwide; the sixth most common cancer and the third most common cause of cancer fatalities


. Most

HCCs are the result of an infectious agent and there are only limited animal models that can be used to explore the basic mechanisms and progression from infection to malignancies 3 .


The animal was provided with supplemental oxygen via cone mask and placed on a heating pad. Additional thermal support was provided with a heat lamp directed on the animal in the cage. A 6 mL injection of sterile saline was administered subcutaneously over the right and left thoracic region (3 mL each side). Clinical appearance did not improve despite supportive measures. The animal was euthanized, blood was collected via cardiac puncture, and a complete necropsy performed.

Figure 1: A large, multilobular, tan mass (M) was adhered to the caudal side of the right liver lobe. More raised, multilobular, tan or white masses (N) and flat discolored foci (arrows) were observed in other liver lobes. The intervening hepatic parenchyma was mottled due to bridging bands of yellow tissue (i.e.

“nutmeg” pattern).

Figure 3: A section of liver from a clinically normal age-matched control Nile grass rat. Note that the structure of hepatic cords and sinusoids was normal, and both portal triads (P) and central veins (C) were identified easily. H&E,



To the authors’ knowledge, this case represents the first case of hepatocellular carcinoma in the Nile grass rat.

Further characterization of the pathogenesis of this disease in this species would prove to be useful by expanding the available animal models for studying HCC.


A large mass (3.7 x 2.8 x 1.5 cm) comprised of coalescing tan/white and clear (presumably cystic) nodules was adhered to the caudal surface of the right lobe of the liver.

Smaller, variably colored, raised nodules were observed on several surfaces of the left lobe. The intervening parenchyma had a diffuse pattern of intersecting white striations separating dark brown foci (i.e. a “nutmeg” appearance).

Mild to moderate bilateral polycystic kidney disease was also noted.


Significant microscopic findings included metastatic hepatocellular carcinoma in the lumen of the right atrium of the heart, myocardial degeneration of the left ventricle and septum with a chronic left atrial thrombus, and chronic amyloidosis of the kidneys leading to protein-losing nephropathy. Thrombi also were noted in the pulmonary microvasculature. A leukocytosis with increased numbers of degenerative neutrophils, nucleated RBCs, and reduced platelets was detected on the complete blood count. Severe hypoglycemia (4 mg/dL) along with increased hepatic and renal values was noted on the serum chemistry profile.

Other incidental findings (intervertebral disc disease and sternum cartilaginous degeneration) were consistent with degenerative changes in an aged grass rat.


1. Noda K, Melhorn MI, Sandi S, Frimmel S, Tayyari F, Hisatomi T,

Almulki L, Pronczuk A, Hayes KC. 2010. An Animal Model of

Spontaneous Metabolic Syndrom: Nile Grass Rat. FASEB J.


2. Guo Y, Klein R, Omary RA, Yang GY, Larson AC.

2011. Highly Malignant Intra-hepatic Metastatic

Hepatocellular Carcinoma in Rats. Am J Trans Res.


3. Roger AB, Fox JG. 2004. Inflammation and Cancer:

Rodent Models of Infectious Gastrointestinal and

Liver Cancer. Am J Physiol Gastrointest Liver

Physiol. 286: G361-G366.

Idiopathic alopecia in male grey short-tailed opossums (Monodelphis domestica)

Christian C. Hofer


, John D. Harder


, Carrie Freed


University Laboratory Animal Resources


& Department of Evolution, Ecology, and Organismal Biology



A small colony (2 female, 18 male) of grey short-tailed opossums (Monodelphis


) obtained from a long standing closed colony were used for a mammology course to demonstrate mating behavior. Four of the male opossums (age 15-20 months) presented with a localized, patchy alopecia primarily on the dorsal pelvic region and partially extending laterally over the rear limb (Fig. 1). The underlying dermis was not inflamed, crusted, or irritated and the lesions did not appear to be pruritic. No broken hairs, indicative of barbering, were noted.

Figure 1: Photographs of representative alopecia lesions on 2 of 4 male opossums. Thinning of the hair coat is evident on the dorsal pelvic regions and visibly extends down the lateral rear leg (far right).


Initial ante-mortem non-invasive diagnostics (tape test) did not identify any ectoparasites and the animals were regularly observed by veterinary personnel to monitor progression of the lesions. Minimal changes were noted during the observation (~6-8 weeks). Following course completion, males were euthanized and gross necropsies performed on animals with lesions and non-affected age matched animals. Gross necropsies identified no significant findings and additional diagnostics were performed; skin scrape, pelt exam, and hair pluck for dermatophyte test medium. All tests were negative with the exception of a single tape test which revealed an apparent mite egg (Fig. 2). Definitive speciation is not possible without adult parasites present. A complete necropsy and CBC was conducted on a single animal with alopecia. Skin from two additional animals (one with alopecia, one without) was also submitted for histological evaluation.

When compared with published reference ranges for M. domestica, the CBC revealed a leukopenia

(4.58K/uL) with a relative increase in neutrophils and decrease in monocytes along with a mildly elevated HCT (46.6%). The complete necropsy revealed no significant systemic lesions and aside from mild alopecia the absence of overt clinical disease makes these findings difficult to definitively identify the reason for these hematological abnormalities.

Figure 2: Photomicrograph of an apparent mite egg attached to a hair follicle.


A 2.0 X 7.0 cm area of alopecia and yellow crusting was noted on the ventral cervical midline of a 20 month-old male (Fig. 3). This area corresponds to the location of the suprasternal glands found in some males of this species and used for chemical communication. Histologically, abundant sebaceous and apocrine glands were identified along with a multifocal suppurative folliculitis (Fig. 4). Small numbers of gram positive bacteria were noted focally on a section of the skin from ventral cervical area, however this finding appeared incidental and did not appear to be correlated with the alopecia noted in the dorsal pelvic region.


Figure 3: 2.0X7.0 cm area of alopecia and yellow crusting on ventral cervical midline, (yellow circle) corresponding to the published location of the suprasternal glands :

* *


Figure 4: H&E stained section of skin from ventral cervical midline (suprasternal gland). Note the abundant glandular structures (black asterisk) and the infiltrating neutrophils consistent with suppurative folliculitis.

Skin sections from the area of alopecia on the dorsum and ventrolateral flank identified small numbers of 1-3 μm, round structures distributed multifocally on the epidermal surface within keratin and follicular infundibulum. These structures stained positively with Gomori’s methanamine silver (GMS) stain and do not exhibit budding

(Fig. 5). These findings were not consistent throughout animals with alopecia and were also found in a non-affected age matched control animal that skin was submitted for histological review (Fig. 6).

Figure 5: GMS stained section of skin from alopecia lesion on ventrolateral flank of a 20-month-old opossum. Note the 1-3 μm, round yellow stained yeast structures within the keratin (black arrows).

Figure 6: H&E stained section of skin from a normal age-matched opossum without alopecia. There are

1-3 μm, round structures within the keratin consistent with those identified in the other slides.

Note there are no lesions evident in the underlying epidermis, dermis, or adnexal structures.


Opossums are a USDA regulated species. They were individually housed in standard laboratory rat cages with wire tops and wood chip bedding on a 14:10 hour light-dark cycle. Temperature and relative humidity were maintained at 75 ±5°F and below 25% respectively. Diet consisted of a commercially formulated fox kibble diet (Fox Regular

Gro & Furring, National Feeds) with fresh fruits (apples & bananas) provided for enrichment. Additional environmental enrichment consisted of shredded paper for nesting and rodent hide boxes.


In domestic animals, alopecia is a common complaint of pet owners and hair loss in humans affects both males and females and can be a significant problem for those affected. Causes of alopecia include multiple etiologies; infectious, autoimmune, inflammatory, neoplastic, physical, chemical, or congenital.

Specifically defined disorders manifesting as hair loss include alopecia areata, a nonscarring inflammatory alopecia thought to have an autoimmune pathogenesis and androgenic alopecia (“male-patterned-baldness”) which is the most common form of alopecia affecting humans 2 . Animal models of alopecia include multiple rodent species, particularly C3H/HeJ mice and DEBR rats 3 macaque (Macaca arctoides



along with the stump-tailed


In these cases of alopecia, there was not an underlying infectious or parasitic component to the pathogenesis identified. This suggests that future cases of similarly presenting alopecia in colonies of M. domestica may be managed conservatively, ensuring that the animals’ overall health and well-being is maintained. A more thorough work up including endocrine function assays and further histological characterization of the areas of alopecia would be required to confirm a pathogenesis and determine the potential value this species as an animal model for alopecia.


1. Evans KD, Hewett TA, Clayton CJ, Krubitzer LA, Griffey SM. 2010. Normal Organ Weights, Serum Chemistry, Hematology, and

Cecal and Nasopharyngeal Bacterial Cultures in the Gray Short-Tailed Opossum (Monodelphis domestica). JAALAS 49(4):401-406.

2. Wiedemeyer K, Schill WB, Löser C. 2004. Diseases on Hair Follicles Leading to Hair Loss Part 1: Nonscarring Alopecias.

Dermatology for the Clinician

. July/August: 209-214.

3. McElwee KJ and Hoffman R. 2002. Alopecia Areata – Animal Models. Clin Exp Dermatol. 27:410-417.

4. Sundberg JP, King LE, Bascom KC. 2001. Animal Models for Male Pattern (Androgenetic) Alopecia. Eur J Dermatol.11(4): 321-325.


Special thanks to Krista La Perle, DVM, PhD, DACVP Director, Comparative Pathology

& Mouse Phenotyping Share Resource, The Ohio State University, College of Veterinary


Surface Disinfection of Exam Gloves as an Alternative to

Using Sterile Surgeon’s Gloves for Rodent Survival Surgeries

Dana M. LeMoine, Valerie K. Bergdall


, and Carrie Freed


University Laboratory Animal Resources



The Guide

3 requires adherence to aseptic technique for survival surgical procedures in rodents. This includes, among other things, the use of sterile surgical gloves.

Recommendations for achieving asepsis may be modified provided that alterations in technique meet the same performance standards.


The recommendation to wear sterile surgical gloves for rodent survival surgeries exists to reduce the risk of postsurgical infection, which negatively impacts the animals’ well-being and the quality of research data. Many laboratory workers fail to follow this recommendation, mainly due to the high cost of sterile surgical gloves.


Alternatives to expensive sterile surgical gloves would be helpful to improve investigator compliance with The Guide.

Disinfectant solutions such as 70% isopropyl alcohol and

1.00% hydrogen peroxide & 0.08% peracetic acid (HP/PA) are readily available within most animal facilities. Although the HP/PA solution is considered a chemical sterilant with appropriate contact time, 4 the Guide states that alcohol is not considered a sterilant nor high-level disinfectant.


Regardless, AAALAC recommends evaluating its use on a case-by-case basis.



Both alcohol and HP/PA disinfectants would decrease the level of microbial contamination on exam gloves, based on bacterial cultures, to a level comparable to sterile surgical gloves.


1. Cooper DM, McIver R, Bianco R. 2000. The thin blue line: a review and discussion of aseptic  technique and postprocedural infections in rodents. Contemp Top Lab Anim 39:27–32.

2. Howard HL, Haywood J, Laber K. 2001. Alcohol as a disinfectant. AAALAC International 

Connection. Winter/Spring;16.

3. Institute for Laboratory Animal Research. 2011. Guide for the Care and Use of Laboratory 

Animals. 8th ed. Washington, DC: National Academies Press.

4. Rutala WA, Weber DJ. 2004. Disinfection and sterilization in health care facilities: what  clinicians need to know. Clin Infect Dis 39;702–709.


Gloves: standard latex and nitrile exam gloves stored inside microisolator mouse cages, sterile latex and nitrile surgical gloves

Disinfectants: 70% isopropyl alcohol and HP/PA solution (Spor-Klenz)

PPE: scrubs, isolation gown, bouffant cap, face mask


n=8 for each combination of glove type, hand washing and disinfectant

• Hands either remained unwashed or were washed for 1 min. with triclosan soap.

• Gloves were donned inside a biosafety cabinet.

Spray Disinfection: Both sides of the gloves were sprayed with disinfectant from a distance of 30cm and hands were rubbed together until disinfectant dried.

Culture: Fingertips of one hand were swabbed inside a biosafety cabinet. (Fig. 1) Swabs were incubated in 5 mL BHI broth for 24h at 37°C.

Fig. 1

Run-in-place: Careful to avoid contamination, the experimenter flexed and extended fingers while running in place for 5 minutes to simulate movement and moisture accumulation that occurs during surgery.



Open gloving

Run‐in‐ place





Clean  gloving



Spray  disinfect



Run‐in‐ place




• Cloudy broth was considered positive for bacterial growth and clear broth was considered negative. Gloves

“passed” if they were negative for bacterial growth after disinfection and after the run-in-place activity.

(Figure 2)

• A subset of positive cultures were plated on Sheep Blood Agar and incubated for 24h. (Figure 3) Species cultured were identified using Gram staining, biochemical identification test strips, and Mannitol Salt Agar.

Fig. 2: Positive broth tube (left) and negative broth tubes

(middle, right)

Fig. 3 Positive sample plated on

Sheep Blood Agar


• 52.3% of exam gloves were negative for growth immediately after donning

• No effect of glove type or hand washing was identified, 96.9% of gloves disinfected with HP/PA, compared to

56.3% of gloves disinfected with alcohol were negative after disinfection at C2 (Figure 4)

• Exam gloves were considered “passing” if both post-disinfection and post-activity cultures were negative.

Compared to sterile gloves, HP/PA-disinfected gloves were not significantly different while alcohol-disinfected gloves were significantly different (p<0.05) (Figure 5)


Figure 4: Culture Results Separated by Hand Washing and Glove Type

Hand Washing



Glove Type

Sterile Latex

Sterile Nitrile



Sterile Latex

Sterile Nitrile




















# Positive Cultures

C1 C2 C3





















% Passing













Alcohol Disinfection

HP/PA Disinfection

Open Glove Technique

0 50

Figure 5: Percentage of Gloves Considered Passing



• Disinfection of exam gloves with HP/PA solution resulted in the same level of asepsis as did sterile gloves for rodent survival surgeries

• Hand washing with antibacterial soap did not impact the initial contamination level of the gloves provided that care is taken to avoid skin contact with the outer glove surface when gloving

• Alcohol did not consistently or reliably eliminate bacteria from exam gloves


• HP/PA disinfection of exam gloves performs as well as sterile gloves for rodent survival surgery.


The American Society for Laboratory Animal Practitioners and Pfizer

Inc. for financial support. Thank you to Joann Petty who provided her microbiological expertise during the planning and execution of this research project and the staff of OSU University Laboratory Animal

Resources for their support of this project.

Autoclaving Exam Gloves as an Alternative to Using

Surgeon’s Gloves for Rodent Survival Surgeries

Dana M. LeMoine, Valerie K. Bergdall


, Carrie Freed


University Laboratory Animal Resources



The Guide

2 requires adherence to aseptic technique for survival surgical procedures in rodents. This includes, among other things, the use of sterile surgical gloves.

• Recommendations for achieving asepsis may be modified provided that alterations in technique meet the same performance standards.


• The recommendation to wear sterile surgical gloves for rodent survival surgeries exists to reduce the risk of post-surgical infection, which negatively impacts the animals’ well-being and the quality of research data.

• Many laboratory workers fail to follow this recommendation, mainly due to the high cost of sterile surgical gloves.


• The purpose of this study was to evaluate the performance of autoclaved latex and nitrile exam gloves as an alternative to the use of sterile surgical gloves for rodent survival surgeries.

Figure 1

Figure 3

Figure 2

Figure 4


Figure 7: % of Gloves Passing - Based on Performance

Sterile Gloves

Exam Gloves



X Sterile



E Sterile



Autoclaved Exam Gloves

0 20 40 60 80







Figure 8: Pressure Test Data (cm H



% usable Mean Peak Pressure

100.00% 18.00 +/- 1.60





19.10 +/- 0.20

16.50 +/- 1.47

30.10 +/- 1.00

26.00 +/- 0.00

162 97.50% 20.50 +/ 1.18


Mean Pressure Loss

7.02 +/- 5.29

4.25 +/- 1.92

2.19 +/- 2.83

14.29 +/- 0.90

12.50 +/- 0.45

8.75 +/- 1.17


Steam sterilization of standard exam gloves would provide for a level of asepsis comparable to sterile gloves, without negatively impacting glove performance.



Open  gloving







Gloves were visually inspected for defects between each step





• Latex and nitrile exam gloves were inspected for defects then packed with folded cuffs in a drape with (A) or without surgical instruments (B), or in an autoclave pouch (C) (n=10 per pack), and autoclaved. (Figure 1)

• The top, middle and bottom pairs from each pack were evaluated

• Gloves were tested on the day of sterilization, 3 days later, or 7 days later

n=6 for each combination of glove type, pack type & days post-sterilization

• Unsterilized exam gloves and sterile surgical gloves were also tested

Stretch Test: Each finger (A) and both sides (B) of the cuff were stretched

15cm (Figure 2)

Performance Test: Experimenter placed 5 simple interrupted sutures in a synthetic model (Figure 3)

Pressure Test: Using an anesthetic machine, gloves were affixed to an Fcircuit and inflated with oxygen (3 L/min), with the pop off closed, until the pressure plateaued to identify peak pressure. (Figure 4) Oxygen flow was turned off for 5 minutes and pressure loss was calculated


• 22.8% of autoclaved latex exam gloves were found to be unusable because they could not be donned without breakage or otherwise breaching aseptic conditions (Figure 5).

94.6% of these unusable gloves came from a single box.

• Of gloves that underwent further testing, 0.8% of autoclaved latex gloves and 2.47% of autoclaved nitrile gloves acquired defects during testing (Figure 6).

Figure 5

Figure 6

• For passing, gloves had to be wearable and successfully complete the performance tests without grossly observable defects (Figure 7)

• Peak pressure and pressure loss means for autoclaved exam gloves were not significantly different than standard exam gloves. Autoclaved nitrile exam gloves had significantly lower peak pressure than that of sterile nitrile surgical gloves (p<0.05). Both autoclaved nitrile and latex gloves had significantly lower pressure loss than the corresponding sterile surgical gloves (p<0.05) (Figure 8)


• Nitrile exam gloves survived autoclaving and performed as well as nitrile surgical gloves. The latex exam gloves that did not survive the autoclaving process were immediately identifiable upon opening the packs, those that survived performed well.

• The autoclaving process did not impact the exam gloves to a degree detectable by the pressure test, suggests their integrity was not compromised.


Exam gloves that can be donned after autoclaving without visible defects perform as well as sterile surgical gloves


1. Cooper DM, McIver R, Bianco R. 2000. The thin blue line: a review and discussion of aseptic technique and  postprocedural infections in rodents. Contemp Top Lab Anim 39:27–32.

2. Institute for Laboratory Animal Research. 2011. Guide for the Care and Use of Laboratory 

Animals. 8th ed. Washington, DC: National Academies Press.


The American Society for Laboratory Animal Practitioners and Pfizer Inc. for financial support. Thank you to OSU University Laboratory Animal Resources for their support of this project.


The Nile grass rat (Arvicanthis niloticus) colony at The Ohio State University was obtained from Michigan State University (MSU) in 2009.

These are descendants of 29 animals imported from the Masai Mara National Reserve,

Kenya to MSU in 1993. Grass rats typically live in family groups consisting of one adult male, one adult female, and one or two generations of offspring. They rest and sleep in burrows located at the base of bushes with several runways used by the animals when foraging. Being diurnal rodents, grass rats are active on the ground during the day, especially in the hottest period, around 1:00-3:00 in the afternoon; but rarely emerge after sunset. In the natural environment, they have adapted to dealing with dramatic seasonal changes such as rainfall variations. They must survive severe shortages of water and food during the dry season, as well as the floods and mud produced by extraordinarily heavy rainfall. They are prolific breeders during the rainy season, but reproduction significantly decreases during the dry periods.

The Nile grass rat, a USDA-regulated species, is increasingly used as a research animal model investigating a variety of applications ranging from spontaneous metabolic syndrome, retinal diseases, and behavioral research.


Hair loss was intermittently observed in the colony of group-housed Nile grass rats used in a behavioral research study. Animals were routinely separated by gender and group-housed following weaning in conventional rat cages with wire tops and aspen bedding. At approximately 3-4 months of age, hair loss was noted in several cages of group-housed female grass rats. PVC pipe huts and

Nylabone® toys were added to the cage for enrichment. The appearance and pattern of the hair loss was suggestive of barbering. Clinical signs suggestive of barbering behavior continued until the animals were separated and singlyhoused because of IACUC-approved protocol requirements. Within 10 days of isolation, regrowth of hair was evident in all animals and continued until the completion of the study, 68 days later, by which time the hair coat had nearly returned to normal (Figure 1). Skin samples were submitted for histopathology at the conclusion of the study (Figures 2 and 3).

Barbering in a colony of Nile grass rats

(Arvicanthis niloticus)

Holly A. Bacon


, Christian C. Hofer


, Famke Aeffner


, and Dondrae J. Coble


University Laboratory Animal Resources


& Department of Veterinary Biosciences



Figure 1:

Images of a 3-4 month old female grass rat representative of other animals within the colony. Day 1 marks the time point animals were singly housed.

Day 1

Day 17

Day 10

Day 34


The skin of the affected regions did not appear inflamed and pruritus was not present.

Additional diagnostics such as pelage tape tests, skin scrapes, and fur mite PCR were negative.

Day 62 Day 68


Photograph (left) of typical presentation of barbering in mice. Note the gross absence of hair within the lesion and sharp “razored” edges. Photomicrograph

(right) of barbering lesion histologically in a mouse with characteristic findings similar to those seen in Fig. 3.

H&E stain, 10x magnification, bar = 50μm


Figure 2:

Section of normal haired skin of a

Nile grass rat. Sample taken from an area unaffected by barbering. Image shows intact adnexal unit composed of hair follicle containing intact hair shafts as well as sebaceous glands.

Adjacent dermis and epidermis are devoid of significant histological findings.

H&E stain, 10x magnification, bar = 50μm

Figure 3:

Section of haired skin of a Nile grass rat barbering. Image shows three disrupted adnexal units composed of hair follicles and sebaceous glands. The right hair follicle is empty, while the middle hair follicle displays a small remnant of a hair shaft (hair plucked). The left hair follicle shows a shortened hair shaft

(chewed on). Adjacent dermis and epidermis are devoid of significant histological findings.

H&E stain, 10x magnification, bar = 50μm


Barbering is an abnormal grooming behavior of laboratory rodents. The hair and whiskers are often plucked, pulled, or chewed, resulting in alopecia (hair loss) to the affected areas. Some rodents have been found to barber due to stress, inappropriate caging, boredom, and even heredity. Many studies have theorized that it is a social behavior; however animals housed singly have also been shown to demonstrate barbering. Self-barbering is most commonly observed on the abdominal region and front legs, whereas barbering by a conspecific is most commonly observed on the muzzle, head and shoulders.

Based on clinical presentation and diagnostic tests revealing no underlying infectious or parasitic etiology for observed hair loss, it is reasonable to classify this as barbering. Comparison of these findings to those more commonly seen in other laboratory rodent species (particularly mice) demonstrates significant similarities between species



Special thanks to: Randy J. Nelson, PhD and Laura K. Fonken, PhD for access to their Nile grass rat colony and assistance during sample collection and photography.

Thanks also to the Smale lab at MSU for the background information on the grass rat colony.

Ulcerative Dermatitis on the Muzzle and Ventral Neck in a colony of Prkar1a Knockout Mice on a FVB/N background

Matthew K. Hogan, Daphne R. Pringle, Carrie Freed

University Laboratory Animal Resources


Ulcerative dermatitis (UD), a common condition of laboratory mice on a

C57BL/6 background strain, is considered to have a multifactorial etiology.

An increased incidence of UD was noted in a colony of mice serving as models of follicular thyroid cancer carrying a cre-mediated, thyroid specific ablation of the floxed Prkar1a gene on a predominantly FVB background.

Unlike the classic mid-scapular and dorsal lesion presentation, mice 6 months-1 year of age, presented with bilateral erythemic, alopecic, raw foci on the muzzle and/or raw moist edematous lesions to the ventral portion of the neck, all displaying extreme pruritus. Incidence within the colony reached 30%. A presumed clinical diagnosis of UD was made on the basis of clinical signs and treatment with topical antibiotics and systemic non-steroidal anti-inflammatory (NSAID) drugs was initiated.

Bacterial cultures noted E. coli and Klebsiella, but lesions did not heal despite long-term treatment with systemic antibiotics. Mice were humanely euthanized and tissues submitted for necropsy. Histologic findings indicated substantial UD in conjunction with systemic changes consistent with an appropriate immunological response to long standing systemic inflammatory condition. The lesions continued to sporadically erupt within the colony, but have decreased in incidence based on selective breeding by the researcher, supporting a genetic component. An update to the early removal criteria of the protocol now addresses the adverse effects of this phenotype. Subsequently, IACUC approval was granted for long term systemic treatment with NSAIDs to provide relief of pruritus and minimize self-mutilation until mice neared scheduled endpoints, upwards of one year with either metastatic carcinoma or benign adenoma development. UD lesions of the muzzle and neck region are rarely reported. Despite a FVB/N background, we presume that the unique presentation of UD is related to the genetics of this mouse and specifically the absence of the Prkar1a gene.


Approximately 15-20, six through twelve month old mice carrying null mutations of the Prkar1a gene presented over a six month period with the following clinical signs:

• Erythematous, ulcerative foci on the muzzle (Figure 1)

• Ulcerative, moist edematous lesions on the ventral neck (Figure 2)

• Intense pruritus

Muzzle alopecia (Figure 3) with no underlying break in the epidermis was frequently observed prior to the development of the more moist erythematous lesion. A 30% incidence rate was calculated for the colony including animals presenting with one or more of the above clinical signs.


Figure 1

Figure 2

Figure 3


Two PRKAR1A-KO mice initially presented with erythemic, ulcerative foci on the side of the muzzle (Figure 1), classic intra-scapular UD was also noted on one mouse to be dry and healing. Lesions did not resolve despite long term analgesic treatment (30 days) followed by long term antibiotic treatment (25 days).

Euthanasia was recommended.


Triple antibiotic ointment



Ibuprofen 30 mg/kg in  water bottle or          

Carprofen 5 mg/kg SQ SID



Enrofloxacin 30 mg/kg in  water bottle or      

5 mg/kg SQ SID

New cases were observed with similar muzzle lesions

+/- ulcerative lesions along the ventral portion of the

Neck (Figure 2). Intense pruritus was observed.

Aerobic Cultures revealed growth of E. coli & Klebsiella spp.

Systemic NSAIDs (in the water bottle or SQ); +/- systemic antibiotics (in water bottle) were provided in combination with various topical treatment modalities :

• Lanolin (15.5%)/petrolatum (53.4%) ointment

• Betadine solution applied topically (10%)

• A/D ointment applied topically

The researcher began to select for offspring from non affected mice to pair for breeding. Animals with ulcerative lesions remained until study endpoints (euthanized at 6 months - 1 year) only when lesion progression and pruritus could be controlled by treatment modalities.


Muzzle lesion (Index case):

Findings were supportive of muzzle UD with systemic changes consistent with long standing inflammatory response. Superficial bacteria were present in the fibrin crust covering the ulcer only.

Ventral neck lesion:

Marked focally extensive, UD was noted. Intralesional bacteria and hair fragments were also present and were deemed likely sequelae of the intense pruritus and not considered as primary etiology.

Necropsy findings did not indicate secondary bacterial infection as a key component to the development of lesions, consistent with the lack of improvement observed on antibiotics.


• A strain of mice at OSU, with genetic manipulations resulting in the absence of the Prkar1a gene, presented with an increased incidence of

UD in the areas of the muzzle and ventral neck.

• Management of mice, lacking Prkar1a gene and developing UD should include:

1. Selective breeding strategies to remove the most significantly affected mice from the breeding colony

2. Long-term systemic treatment with an NSAID and topical therapy with ophthalmic triple antibiotic ointment to provide relief of pruritus, minimize self-mutilation, and prevent secondary infection


Although curative treatments were not identified, management of the pruritus therapeutically allowed mice to reach study endpoints


The laboratory of Professor Lawrence S. Kirschner

Internal Medicine-Division of Endocrinology,

The Ohio State University

ULAR Medicine Technician staff

Establishment, Implementation, and Refinement of a 

Large Animal Sanitation Monitoring Program

Joann Petty, Tammy Jones, Stephanie Lewis

University Laboratory Animal Resources


The eighth edition Guide for the Care and Use of Laboratory Animals recommends regular evaluation of sanitation effectiveness in both manual and automated processes.

While a rodent sanitization monitoring program has been in place at our institution, establishment of a formal large animal sanitation monitoring program was necessary.

Numerous components from transport cages/carts, rabbit cages, environmental/food enrichment devices, and common shared equipment (scale, feed bowls, etc.) were cleaned using standard rack and tunnel washer procedures. Large animal enclosures were foamed and rinsed using a commercially available alkaline based cleaner, then foamed, scrubbed, and rinsed using an acid based cleaner, and finally a disinfectant was applied and rinsed. All of the components were evaluated prior to and after sanitization to determine the efficacy of the current standard operating procedures, cost analysis, and evaluate the new testing plan using both microbiologic culture (RODAC) and an organic material detection system (ATP). According to the product information guide, RODAC plate sanitation thresholds for critical contact areas are 0-15 colonies per plate and less than 30 relative light units for ATP. Results of preliminary testing showed that the majority of our current sanitization processes are effective and manufacturer recommended pass standards are adequate, but potential exists for refinement and optimization. Both

RODAC and ATP must be employed regardless of cost, as some unique equipment design does not allow for RODAC testing (i.e. lixit). A smaller subset of areas could be tested and still provide enough information to evaluate proper sanitization. Using both the

RODAC and ATP testing on a quarterly basis is a convenient, efficient, affordable way to establish and implement a large animal sanitation monitoring program.


• The Guide for the Care and Use of Laboratory Animals (8

th edition)

recommends regular evaluation of effectiveness for automated and manual sanitation processes.

• Large animal enclosures, enrichment devices, and other shared equipment were not being consistently and regularly evaluated for sanitation effectiveness.

• The current standard operating procedure of a 3-step cleaning process (acid cleaner, alkaline cleaner, disinfectant) had never been evaluated for effectiveness at our institution.


• Each piece of equipment was sampled a minimum of 5 times before and after manual or automated (cage wash) sanitization.

• Direct contact areas and areas deemed most difficult to sanitize were sampled using Hygiena ATP (adenosine triphosphate) Ultra swabs or

BD RODAC (Replicate Organism Detection and Counting) plates.

[Figure 1]

Figure 2: ATP Procedure

Figure 1:

RODAC plates

All components (enclosures and enrichment devices) were sampled using the following techniques:

• RODAC sampling was utilized for all flat surfaces.

RODAC samples were taken by labeling the plate, removing the lid and touching the plate to the surface for

5 seconds and placing the lid back on. Plates were incubated for 48 hours at 35°C and then observed for quantification.

• ATP swabs were used on all surfaces. ATP samples were obtained by swabbing a 4 by 4 inch square area, the swabs activated, and then analyzed in the Hygiena

Sure System Luminometer. [Figure 2]


• In large animal enclosures (which house multiple large animal species), the areas tested were the top of the run, the side ledge, the wall , the wire front, and both types of grates

[Figure 4]

• Two individual cages on each rabbit cage bank were tested. The hutch, divider, feeder, lixit, grate and pan were tested in each cage. [Figure 5]

• Enrichment such as devices rings,

Nylabones, Kongs, and plastic balls were tested.

[Figure 6]



Wire Front

Figure 4: Large Animal Enclosure




Figure 5: Rabbit Cage

Figure 6: Enrichment Devices


Pass/Fail Threshold Determination

• Thresholds can vary between test points due to types of surfaces, so establishing a facility specific pass/fail value is recommended.

• The threshold is best determined by testing predetermined components over several days.

• The average and standard deviation was calculated for the RLU values.

• The limits are set as:

• Less than or equal to the mean

RLU is passing.

• The mean RLU to less than 3 times the standard deviation is cautionary.

• Greater than or equal to the mean RLU plus 3 times the standard deviation is failing.

• For values where a pass rate calculated out to be 0-1 a minimum of 10 was used as a standard.

Efficacy of 3-Step-Manual Cleaning Process

(Current SOP)

Pass/Fail Threshold Calculation

Using a minimum of 5-10 test replicates

Pass ≤ Mean RLU

Caution ≥  Mean RLU < 

Mean + 3 SD

Fail ≥ Mean RLU + 3 SD

Current Cleaning Processes

Automated(Rack and Tunnel Wash)

• Rabbit cage banks and enrichment devices


• Large animal enclosures

Post Acid cleaner

Post Alkaline cleaner Post Disinfectant




Manual Process:

1. Foam with a dilution of acid cleaner from top to bottom in an 8-10ft. wide area for

10min of contact time. Rinse with water.

2. Foam with alkaline cleaner from top to bottom in an 8-10ft. wide area. Let sit for

10min. Rinse with water.

3. Apply dilution of disinfectant; scrub any remaining debris and let sit for 10min.

Rinse with water.


ATP Standards in Relative Light Unit’s (RLU’s)

Rabbit Cages Canine Runs

Area Tested Mean 3 s.d. Pass Caution Fail Area Tested Mean 3 s.d. Pass Caution Fail

Divider* 0 1 0‐1 1 >1 Wall* 9 67 0‐9 10‐75 >76





















Enrichment Devices






>4 Ledge

>3 Wire Front

0 Top

>4 Orange Grat

>18 Gray Grate*







147 0‐42 43‐187

226 0‐55 56‐280


0‐17 18‐80


236 0‐46 47‐281 >282

Swine Runs






Area Tested Mean 3 s.d. Pass Caution Fail Area Tested Mean 3 s.d. Pass Caution Fail

Ring Toy 7 25 0‐7 8‐31 >32 Wall* 0 0 0 0 >0

Green Bone 1 6 0‐1 2‐6 >7 Ledge 11 40 0‐17 18‐56 >57

Bumpy Bone 30

Kong 23


153 0‐30 29‐182 >183 Lixit

110 0‐23 24‐132 >133 Wire Front



218 0‐84 85‐301 >302

26 0‐17 18‐42 >43

9 1 0‐9 10 >10 Top 33 104 0‐32 33‐173 >173

*Also tested by RODAC

Percentage Pass/Fail Rate for Large Animal Sanitation


Mean pass rate was 79.5%.

• Less than 26,000 RLU correlate with RODAC test results of less than 10

CFU per plate. All RODAC test results were less than 10 CFU.

• The cost of ATP swabs were $2.51 per swab and RODAC plates are

$0.70 per swab.


• The use of both types of testing (RODAC and ATP) must be employed, however, RODAC testing should be the primary testing method where equipment design allows (flat surfaces) for financial optimization.

• Based on our average pass rate of 79.5%:

• Quarterly sanitation testing is adequate to efficiently and affordably measure sanitation standards.

• A smaller subset of components would still adequately evaluate sanitation.

• The pass/fail limits should be recalculated once per year and when procedural changes are made to optimize sanitation/hygiene standards.

• A margin of error exists in manual cleaning processes due to variation of animal care staff.

• Percentage of failures was ≤5% for all components, however optimization potential exists in procedural changes to obtain a 100% pass rate(Ex: pre-soak enrichment devices before cage wash).

• For our institution, the 3-step cleaning process is necessary to obtain consistent passing standards in large animal enclosures.

• Implementation of program is easily done by updating standard operating procedures and allocating personnel time and funds for testing equipment.


Thanks to Alison Gallagher, Mike Coats, Alisha Strong, and Mackenzie Nicolaus for assisting with this project.

Customization of Standard Rabbit Dividers

Provides Enhanced Socialization for Singly Housed Rabbits

Candace Hedrick, Michael Rowley, Stephanie Lewis

University Laboratory Animal Resources


Social animals should be housed in stable pairs or groups of compatible cohorts whenever possible. Rabbits are a social species and providing species-appropriate social interaction including auditory, olfactory, tactile, pheromonal and visual cues from conspecifics that are not compatible for pair or group housing due to factors such as age, sex or protocol restrictions can prove challenging. Our institution currently utilizes a commercial side by side caging system that allows for all sensory interaction, with the exception of tactile, when the divider is in place.

One way to provide tactile interaction between individually housed animals and to maximize social interaction is to provide a cage divider that allows for nose touching but restricts further physical contact. To achieve the enhanced social interaction between two individually housed rabbits, 70 holes were drilled measuring 1” in diameter and 2” apart on center into the standard commercially available clear acrylic 31.5” x

12.13” divider. The holes were made using a 1” boring bit, smoothed with a dremel and deburred. The determined hole size allowed for nose touching but restricted further interaction between cohorts. Hole placement was determined by evaluating the upper and lower lips of the divider slide and if the rabbits were on or below the loft/shelter, thus allowing access to cohort on both levels. Upon placement of the modified divider, rabbits were immediately observed using the holes in the divider to nose touch. Uniform results were noted between same-sex side by side caging. By customizing the commercially available standard rabbit cage dividers, we were able to provide a simple, economic method of effectively maximizing the social interaction between singly housed rabbits that would otherwise have limited social contact with cohorts housed on the same level of the caging system.



• Animals were housed in a commercially available 26.8”W x 26.8”D x 17.7”H side by side caging system with removable acrylic dividers

• Modified dividers were used with both New Zealand White and Dutch Belted rabbits

Modification Equipment

• Commercially available 31.5” L x 12.13”H x 3/8” W thick clear acrylic cage divider [Figure 1]

• Initial prototype was created using a 1” boring bit and drill press

• A waterjet cutting machine was used for hole creation during mass production

• Any remaining rough edges were smoothed with a dremel and deburring tool [Figure 2]

Hole Location and Size Determination

• Location, spacing and the number of holes were created to provide the maximum amount of social contact without losing structural integrity of the divider

• 70 holes were drilled measuring 1” in diameter and 2” apart on center [Figure 3]

• Hole placement on the divider allows access to cohorts at all accessible areas within a single cage

[Figure 4]

• 1” diameter hole size determined by rabbit nose size and were made large enough to allow for nose touching


• In pilot study (n=6), all New Zealand White rabbits were observed nose touching within

1 minute of initial introduction of divider [Figure 5]

• Full scale implementation of dividers (n=51) showed subjectively that rabbits behaved similarly to the pilot group

• To date, no injuries have been observed with customized divider use

• The modified dividers allowed for auditory, olfactory, tactile, pheromonal and visual cues from conspecifics

• Additional sensory social enrichment was achieved while working within the constraints of single housing

• In addition to social enrichment, dividers can be utilized to enhance other forms of enrichment such as physical and nutritional [Figure 6]

• Cost Savings

• Aftermarket customization performed by vendor = $40 per unit (+shipping costs)

• In-house customization = $24

• Institutional cost savings of 60%

Hanging Rattle

Strawberry Spinach

Figure 1: Standard unmodified commercially available cage divider

Figure 3: Customized divider design schematic

Figure 5: Example of rabbits nose touching immediately following the introduction of the customized divider

Figure 6: Physical and nutritional enrichment can be placed on/ in the customized dividers as a form of additional enrichment


• In the Guide for the Care and Use of Laboratory Animals (8



rabbits are considered a social species and should be housed in stable pairs or groups of compatible cohorts whenever possible

• There are instances that animals must be singly housed, such as incompatibility or for study-related purposes

• The current housing system utilized allows for auditory and visual interactions with limited olfactory and pheromonal cues from conspecifics and restricts all tactile interactions

• The Association for Assessment and Accreditation of Laboratory

Animal Care International (AAALAC) recommends that cohorts that are unable to have full contact social interaction should have protracted contact such as a perforated barrier on either a part or full time basis

• Perforated dividers are not commercially available from the caging vendor and have to either be modified in-house or performed by the vendor as a special order for modification

• The purpose of this caging modification was to provide an additional spectrum of sensory social enrichment for rabbits that are unable to be socially housed

Figure 2: Boring bit, deburring tool and dremel Figure 4: Customized cage divider


• By customizing the commercially available standard rabbit cage dividers we were able to enhance species-appropriate social interaction for rabbits that would have otherwise been limited

• A cost savings of 60% was achieved by customizing in-house versus being performed by the vendor as a special order for modification

• The modified dividers are a simple, safe, and economic method of effectively maximizing social interaction between singly housed side by side cohorts on the same level of the caging system


Special thanks to Alisha Strong, Tammy Jones, Michael Coats, and Alison Gallagher for their assistance with this project

Foraging Tray Customization for Cynomolgus Macaques

(Macaca fascicularis) Optimizes Novelty and Sanitization

Candace Hedrick, Michael Rowley, Stephanie Lewis

University Laboratory Animal Resources


Developing novel environmental enrichment devices that promote species-specific behaviors can be challenging as variability, safety, ease of sanitization, and device cost all must be considered. Foraging is a natural behavior in macaques that can be promoted by using a finger board foraging tray in a laboratory setting. Commercially available finger boards can be expensive and offer limited variability within a single product design and can be difficult to mechanically sanitize. In an effort to provide increased novelty with easier sanitization, our institution developed a high density polyethylene foraging board that was cut to measure 7”L x 1-3/4”W x ¾”H with eleven ¾” holes 1” apart on center in an alternating pattern using a ¾” ball-end mill bit, sanded with a dremel and deburred. Board size was designed to allow its use with commercially available and institutionally customized holders.

Compared to flat-bottomed hole designs that most commercially available trays have our unique rounded bottom concave holes were based on cynomolgus macaque digit size with space to allow for natural

“scooping” and “picking” motions. The concave holes were more effectively sanitized in a standard tunnel washer than the commercially available flat-bottom design as determined by an organic material detection system test (ATP) performed after placing various types of typical food enrichment in both designs and then sanitizing them in a standard tunnel washer. In-house production expenses and supplies resulted in an 87.5% cost decrease per unit compared to commercially available products, thus allowing for the development of additional trays and designs. Further customization of the standard tray design being explored includes variation of number, pattern, depth, and diameter of holes which provides greater novelty and can potentially be adapted for multiple non-human primate species. The in-house customization of the foraging tray allowed for more effective sanitization than commercially available products, was cost-effective, and promoted the natural foraging behavior in macaques housed in a laboratory setting.



• High density polyethylene for customized finger board

• A mill was used with a ¾” ball-end mill bit to create smooth ¾” concave holes

• A deburring tool to smooth out any remaining rough edges [Figure 1]

• Commercially available foraging tray holder for device attachment to cage [Figure 6]

Hole Size and Spacing Determination [Figure 2 and Figure 3]

• Hole diameter was based on cynomolgus macaque finger size

• 1” on center spacing was determined to allow for maximum number of holes without compromising structural integrity

Figure 1: Mill bit and

Figure 2: Custom foraging tray

Figure 3: Side view deburring tool schematic comparison of customized and

Testing Process commercial hole designs

• Both the concave and flat bottom designs were evaluated in the same manner

• 3 adhesive foods commonly used for enrichment were measured and placed in 3 holes each [Figure 4]

• Boards were sanitized in a standard tunnel washer and allowed to dry

• Each hole that contained a food material was sampled using Hygiena ATP (adenosine triphosphate)

Ultra swabs

• ATP samples were obtained by circling the entire hole area with the swab, including the creases in the flat bottomed design, the swabs were activated and then analyzed in the Hygiena Sure System

Luminometer [Figure 5]


• The Guide for the Care and Use of Laboratory Animals (8



recommends that animals should receive resources that facilitate the expression of species typical behaviors

• Foraging is a natural species-specific behavior in cynomolgus macaques that is encouraged at our institution

• The commercially available foraging tray has a flat bottomed hole design with creases that we anticipated could retain additional organic debris following sanitation

• Our institution developed a customized foraging tray with a concave hole design to test the effectiveness of sanitization versus the flat bottom hole design

• The purpose of our study was to create a cost effective tray that had a smooth concave surface that could potentially be more effectively sanitized

Figure 4: Custom ray loaded with foods

Figure 6: Customized tray in commercial holder

Figure 5: Hygenia Sure System Luminometer

Figure 7: Cynomolgus macaque utilizing customized tray


Organic Material Detection System Test (ATP) Results

Food Tested


Canned Food


Tray RLU's




Tray RLU's RLU Results





Peanut Butter 17 11 Pass/Caution

Relative Light Units (RLU) test ranges used on a 0-30 pass scale

0-10 Good, 11-29 Caution, 30+ Fail

• Both tray designs passed the ATP test for honey and canned food with relatively little difference in the amount of organic debris present

• Debris was grossly visible in the crease of the flat bottomed hole for the peanut butter sample

• Both tray designs passed with caution for peanut butter, but the concave hole design was borderline for caution while the commercial design was firmly in the caution range

• Overall, both tray designs passed with little variation in the amount of remaining organic debris following sanitization, with the exception of the peanut butter


• When presented to macaques, both the commercial and customized foraging trays were used immediately and effectively [Figure 7]

• It was subjectively observed that the customized concave design allowed for the anticipated scooping and picking motions more effectively by the animal in comparison to the commercially available tray

Cost Savings

• Cost decrease of 87.5% based on commercial price

• Commercial tray = $24 per unit cost from vendor

• In-house customized tray = $3 per unit; production expenses and supplies

• 8 in-house boards can be made for the same cost as one of the commercially available boards

• The cost savings allows for additional novel boards to be created within the same budget of a commercial product


• Both tray designs proved to be effectively sanitizable and showed little difference in remaining organic debris with the exception of peanut butter

• Both tray designs were utilized successfully by subjects

• The most significant difference between the trays was the cost. By reducing the per unit cost of the customized trays by 87.5% and retaining the same budget, we were able to produce a greater number of foraging trays

• Foraging tray prototypes of varying colors, hole depths and diameters, board shapes and sizes, hole number and distribution and additional attached materials/obstacles are currently in development


Special thanks to Chelsea Ellis, Michael Coats, Tammy Jones and Alison Gallagher for all of their assistance with this project

Monitoring the Intraoperative Temperature During Swine Surgery:

An Analysis of Heating Devices

Picture specific  to each poster  here 


Michael Bradley and Dondrae Coble

University Laboratory Animal Resources


The aim of this study was to compare three thermal supplementation devices during  experimental swine surgeries. Currently there are no studies examining the efficacy of different  heating devices during swine surgery.  Swine are suitable animal models for surgical research  and teaching because of their size, physiologic and anatomic similarities to man.  The  cardiovascular and CNS effects of anesthesia can result in intraoperative hypothermia, thus  thermal supplementation is critical during surgery.  The devices compared in this study were a  convective heating blanket, a circulating warm water blanket, and a heated table.  Esophageal  temperatures were recorded every 15 minutes from the onset of anesthesia, during both  survival and non‐survival surgeries. Significant results were observed following data analysis for  the animals in the non‐survival data set.  None of the selected devices maintained  normothermia after the onset of anesthesia, however thermal supplementation minimized the  degree of temperature loss.  The convective heating blanket maintained higher body  temperatures compared to the control after 90 minutes of surgery.  Furthermore, the  convective heating blanket maintained higher body temperatures when compared to the  heated table after 150 minutes of surgery.  Finally, both the convective heating blanket and  circulating water blanket maintained higher body temperatures when compared to the heated  table at 180 minutes.  Interestingly, no device showed a difference from control before 90  minutes of surgical time.  The heated table showed no difference compared to the control at  any time point, out to 180 minutes.  The most effective thermal supplementation device in this  study was the convective heating blanket.


Animals used in the study

Yorkshire Pigs (~50 kg) undergoing IACUC‐approved surgical procedures were used for this research study.  In  survival surgeries, animals were scrubbed and prepped with aseptic technique and covered with drapes. Time  spent in the surgical preparation area after the induction of anesthesia was variable.  For survival surgeries,  additional thermal supplementation provided when body temperature reached 97 º F. In  non‐survival  surgeries, animals were not covered with drapes, transported directly to the operating room, and placed on a  heating device.  In non‐survival surgeries, additional thermal supplementation was provided when body  temperature reached 95 º F.  Animals were anesthetized with Telazol 4 – 6mg/kg IM and maintained with 

Isoflurane inhalant anesthesia.  

Heating Devices Analyzed

Control animals did not receive thermal support and were used for terminal procedures. The Heated Table is  manufactured by Shor‐Line and costs $500‐$900.  This device produces an even heat of 97 º F, heating the  patient by conduction.  The Circulating Water Blanket (CWB) is manufactured by Gaymar Industries and costs 

$289 for the water pump and $17 for each pad. This device circulates hot water (107 º F) underneath the  patient, heating by conduction. It has been shown to be effective in avoiding hypothermia in small animal  patients


.  The Bair Hugger® is manufactured by Arizant Animal Health and costs $1150 for the air blower  and $12 for each single‐use mat.  This device blows hot air (105.8


F) over the patient through numerous holes  in the mat, heating by convection.  It has been shown to be effective in avoiding hypothermia in small animals  and man during surgery



•Bair Hugger® showed a reduced rate of temperature loss in one‐way ANOVA. (P<0.05)

•CWB had the second lowest average rate of temp. loss, with data approaching statistical significance. (P=0.07)

•Esophageal temperature versus time

‒ Bair Hugger® maintains higher body temp. than the control after 90 min.

‒ Bair Hugger® maintains higher body temp. than the heated table after 150 min.

‒ Both Bair Hugger® and CWB maintain higher body temp. than the heated table at 180 min.

•Both Bair Hugger® and CWB had a reduced rate of temp. loss in survival surgeries compared to non‐survival,  approaching statistical significance.  (P=0.073,P=0.053 respectively)


Swine are a common surgical research animal

Swine in Surgery

14 used in a variety of studies including cardiovascular, dermal,  renal, GI and organ transplantation studies.  Swine are utilized because their size, physiology and anatomy are  similar to man


Outside of surgical research, swine are also used as surgical models in teaching exercises

Anesthetic Induced Hypothermia

Normothermia is maintained in a narrow range under normal conditions, with the swine temperature range  being between 101.6

º ‐103.6

º F.

5,14 Hypothermia is a commonly seen effect of anesthesia, and this is due to  several physiologic disturbances.  The temperature at which normal physiologic responses to hypothermia  would occur is decreased under anesthesia 1,10,11,13.

Anesthesia also lowers the basal metabolic rate (BMR) 8 ,  and subsequently body heat production decreases. Furthermore, anesthesia decreases sympathetic tone 2,9 ,  and as a result blood (i.e. heat) becomes preferentially redistributed to the extremities, where heat can be  lost to the periphery


Outside of the thermoregulatory effects of hypothermia, there can be adverse effects  on renal, cardiovascular, CNS, hepatic and immune system function


Purpose of Study

The purpose of this study was to analyze the efficacy of three different heating devices in preventing or  reducing hypothermia during swine surgery.  Part of this analysis would include comparing the cost  effectiveness of the different heating devices.  The results of this study should help shape future heating  device purchasing decisions, in that the most affordable and effective device will be purchased and ineffective  devices will be avoided.










The Bair Hugger® was the best thermal heating device analyzed, followed by the CWB, whereas the heated  table was an ineffective mode of thermal supplementation.  Interestingly, there was no statistical difference  for any device before 90 minutes, which showed that initial loss of internal temperature was irrespective of  the type of thermal supplementation.  This data should be considered during surgical procedures of short  duration (<90 min).  The survival surgeries showed a reduced rate of temperature loss compared to non‐ survival surgeries, and the only difference in procedure was draping of the patient, which showed that  draping alone may provide a form of thermal supplementation.  This study can be used to help guide surgical  heating element purchasing decisions for locations that anticipate doing swine surgery.


1. Bissonnette B. Body temperature and anesthesia. Anesth. Clin.North Am. 1991; 9:849‐864.

2. Cabell LW, Perkowski SZ, Gregor T, et al: The effects of active peripheral warming on perioperative hypothermia in dogs. Vet. Surg. 1997; 26:79‐85.

3. Çengel YA.  Heat Transfer: A practical approach. (2nd ed.). Boston: McGraw‐Hill, 2003.

4. Conover MA, Lennon RL, Rose SH: Evaluation of a forced air patient warming system for hypothermic postsurgical patients. Anesth. Analg. 1989; 68:S59.

5. Gross Dr.  Animal Models in Cardiovascular Research.  New York, New York. Springer, 2009.

6. Guyton AC. In: Textbook of Medical Physiology (ed 8). Philadelphia, PA. Saunders, 1991.

7. Hubbell JAE, Muir WW, Harrison EE: Effect of warm water heating blankets on anesthetic heat loss in dogs and cats. Vet. Surg. 1985; 14:338.

8. Imrie MM, Hall GM. Body temperature and anaesthesia. Br J Anaesth. 1990; 64:346‐354.

9. Machon RG, Raffe MR, Robinson EP. Warming with a forced air warming blanket minimizes anesthetic‐induced hypothermia in cats. Vet. Surg 1999; 28:301‐310.

10. Sessler DI. Central thermoregulatory inhibition by general anesthesia. Anesthesiology 1991; 75:557‐559.

11. Sessler DI. Temperature Monitoring, in Miller RD (ed): Anesthesia (ed 3). New York, Churchill Livingstone, 1990.

12. Sessler DI, Støen R, Glosten B. The Bair Hugger® warmer significantly decreases heat loss to the environment. Anesthesiology 1989; 71:A411.

13. Sladen RN: Temperature regulation and anesthesia. American Society of Anesthesiologists  Annual Refresher Course. 1990; 243:pp 1‐7.

14. Swindle, M. Surgery, Anesthesia and Experimental Techniques in Swine.  Ames, IA. Iowa State Press, 1998.

15. Swindle MM, Smith AC, Hepburn, BJS. Swine as Models in Experimental surgery. J. of Inv. Surg. 1988;1:65‐79.


• This research was supported by an ASLAP Summer Fellowship, sponsored by Pfizer

• ULAR veterinarians: Dr. Freed, Dr. Hickman‐Davis, Dr. Lewis and Dr. Bergdall

• ULAR Surgery Staff: Lori Mattox, Becky Glock, McKrai Petaja, Liz Dean, Crystal Forrider and Shannon Balser

• Summer Externship Director Dianne Harrison

• ULAR residents: Dr. Hofer, Dr. Hogan and Dr. Creamer

• ULAR Health Technicians and Animal Technicians

Impact of Ventilated Caging on Water Intake and

Loss in Four Strains of Laboratory Mouse

Mackenzie Nicolaus, Lisa Joseph, Valerie Bergdall, Ian Davis, Judy Hickman-Davis

University Laboratory Animal Resources


Water consumption by mice is affected by availability of food, temperature, humidity, strain and caging. The goal of this study was to understand water turnover in common strains of mice housed in ventilated or static caging. Transepidermal water loss (TEWL) represents a major component of water balance and TEWL measurement is a new technique for quantification of water turnover in mice. Male and female SCID, SKH, C57BL/6 (C57) and FVB mice were housed 5 to a cage in static or individually ventilated cages (IVC). Hydration levels in all strains were assessed every 48 hours by measuring body weight, TEWL, urine osmolality and water consumption. Intracage temperature and humidity were measured every 48 hours for comparison to the macroenvironment. Static cages were monitored for 7 days and IVC for 14 days before cage change out. Females drank less water than males in all strains. With the exception of C57 strain, IVC housed mice of all strains and sexes drank less water than those housed in static cages. Water consumption in IVC ranged from 3.32±0.4 to 4.8±0.6 ml/day.

TEWL levels for SCID, SKH and C57 mice paralleled water consumption for all housing conditions. TEWL for IVC housed mice ranged from 7.7±2 to 25.9±19 g/m 2 /h compared to 8.8±5 to 10.6±6 g/m


/h for static cages. Temperature and humidity within the cage was significantly higher than the macroenvironment for all housing conditions, mouse strains and sexes.

Temperatures within IVC ranged from 76±2°F to 82±2°F compared to 69±2°F in the room.

Humidity within IVC ranged from 68±18% to 84±13% compared to 28±8% within the room.

These data indicate that macroenvironment measurements do not reflect the intracage environment and demonstrate the impact of caging type on TEWL.



All experiments consisted of 2 cages (5 mice per cage). All experiments were repeated at least once after randomization. Data was analyzed by ANOVA multigroup comparison of means, or by

Kruskal-Wallis and Mann-Whitney nonparametric tests using GraphPad InStat version 3.10 for

Windows (GraphPad Software). Data is reported as ± SEM. Significance level is set at P < 0.05.


All procedures were approved by the Institutional Animal Care and Use

Committee in accordance with The Guide for the Care and Use of Laboratory

Animals. Male and female SCID, SKH, FVB and C57BL/6 mice were obtained from Charles River Laboratories at 8 weeks of age. All mice were housed separated by sex (n=5 per cage) in polysulfone microisolator cages (Super Mouse

750™, Lab Products) containing ~300 ml of ¼” corncob bedding (Bed-o’ Cobs,

The Andersons) with ad libitum access to standard irradiated diet and chlorinetreated reverse osmosis water via 100 mL graduated water bottles (Wahmann

Mfg. Co., Fig 1).


Mice were housed as described in either Experiment 1 or 2. Hydration levels were assessed at the beginning of each experiment and then every 48 hours by measuring weight, TEWL, urine osmolality and water consumption. At the end of each experiment, cages were changed and mice were assigned to a new experimental paradigm.

Experiment 1: Mice were housed for 7 days under static conditions on a free-standing wire shelving rack with 76 cm x 152.4 cm shelves spaced 38 cm apart vertically (3060NS,

InterMetro Industries Corporation, Fig 2).

Experiment 2: Mice were housed for 14 days on an individually-ventilated rack (Lab Products, Fig

3) with ventilation set at a standard flow rate of

40 air changes per hour (ACH).

Figure 2

Figure 1

Figure 3

Figure 4: Cages were modified to allow insertion of the hygrometer probe by drilling a

1/4” diameter hole on the midpoint of the front cage surface, 4 cm from the cage bottom.

Autoclave tape was placed over each hole when measurements are not being made.

Temperature and humidity were measured in control cages in the absence of mice.

Temperature and Humidity:

Temperature and humidity were measured daily inside the cage using a hygrometer (Traceable

Hygrometer Thermometer Dew Point, model #11-661-16, Fisher

Scientific, Fig 4). Room humidity was measured with a Traceable® hygrometer (Traceable Calibration Control Co.) and room temperatures with an Extech big digital hygro-thermometer

(Fotronic Corp.).


Rack ventilation was measured every 48 hrs at each cage location with a cage monitor unit (Enviro-Gard™ model #59018,

Lab Products,). The average ACH was 26.7±0.1, n=238 separate measurements.

Urine Osmolality:

Urine was collected “free catch” and osmolality was measured using a Vapro 5520 vapor pressure osmometer (Wescor Inc.).



Vapor pressure gradient was measured using DermaLab Series SkinLab Combo probe

(Cortex Technology, Hadsund, Denmark, Fig 5, 6).

Measurements are reported in gm/m 2 /h. Hair was removed in a small area on furred mice using Nair

24 hours prior to TEWL measurement.


Nair was used to depilate FVB and

C57BL/6 mice for TEWL testing. Skin was allowed to “recover” for 24 hours post Nair before TEWL sampling. Samples were submitted to Charles

River Laboratories for histopathology from 16 mice either 10 days post final Nair (3 total Nair treatments; 4 FVB and 4 C57BL/6), or 24 hours post final Nair (4 total Nair treatments; 4 FVB and 4

C57BL/6). Submitted samples contained depilated region with normal skin on each side.

Figure 5

Figure 6

The probe measures the rate of water exchange across the dermis. The probe contains an open cylinder with paired sensors which is placed perpendicular to the skin surface.

The probe measures humidity and temperature at each sensor and computes two separate vapor pressures, the difference between the vapor pressures at the two points is used to calculate evaporative water loss from the skin.


TABLE 1: IVC vs. Static Housing Water Consumption

Weight gm

Water mL/d

Water mL/d/25 gm mOsmo/Ltr



Female Male


Female Male


Female Male


Female Male


Female Male


Female Male











































*P<0.05 compared to same strain and sex IVC; **P<0.01 compared to same strain IVC

IVC vs. Static Housing Water Consumption:

Mice housed in static conditions drank more water and had urine that was significantly more dilute (Table 1).

Female mice were ~20% smaller than males and drank less water. Normalized for weight females drank more than males. SCID and SKH hairless mice housed in IVC and static cages drank more water than

FVB mice of the same gender and housing system.



TABLE 2: C57BL/6

IVC vs. Static Housing Water Consumption

Weight gm

Water mL/d

Water mL/d/25 gm mOsmo/Ltr
























*P<0.05 compared to same strain and sex IVC; **P<0.01 compared to same strain and sex IVC


C57BL/6 Mice:

Female C57BL/6 mice drank significant less water than males when housed in static caging but not in

IVC (statistics not shown). Both males and females drank significantly less water and had more dilute urine when housed in static cages as compared to IVC. C57BL/6 mice housed in IVC had significantly higher TEWL levels than

SCID, SKH and FVB mice of the same gender and housing system. Male C57BL/6 mice housed in IVC had significantly higher TEWL than all other strains and genders (Fig 8).

TABLE 3: Temperature and Humidity


Figure 8






Control SCID




78.3±0.4† 80.6±0.3† 81.4±0.3†


68.2±1.7† 73.0±1.6† 79.2±1.8†

C57BL/6 Control SCID









78.0±0.6†* 79.4±0.6†* 76.2±0.5†

69.8±1.2† 73.0±1.6†* 69.9±1.7†

†P<0.01 compared to Control same conditions; *P<0.01 compared to same strain IVC

Temperature and Humidity:

Both IVC and static cages housing mice have significantly higher temperature and humidity levels as compared to the room. IVC systems had higher temperatures and lower humidity levels as compared to static cages Mice caused a temperature increase of 7° to 12°F for IVC and 7° to 10°F for static cages as compared to cages without mice. Mice caused a humidity increase of

22 to 33% for IVC and 35 to 38% for static cages as compared to cages without mice (Table 3).


No lesions could definitively be identified as being related to the Nair treatment (Fig 9). Abnormalities noted were minimal and transition from Naired to normal skin could not be identified except in some C57BL/6 mice. C57BL/6 mice are known to have dermatologic lesions and the pathologist considered the possibility that any changes in skin were strain-related and not due to treatment, or that the strain may have affected treatment-related changes.

Figure 9


Figure 7

Temperature and humidity levels over time:

TEWL levels were not impacted by gender and remained constant despite an increase in temperature and humidity over time for both IVC and static cage systems (Fig 7).


The type of housing system, gender and strain impact water turnover in hairless and furred mice:

Female SCID, SKH and C57BL/6 mice consistently drank less water than males for both housing conditions -- FVB females drank significantly less than males in IVC but not static cages (statistics not shown)

SCID, SKH and FVB mice housed in static cages drank more water and had lower urine osmolality as compared to the same strain housed in IVC

C57BL/6 mice housed in static cages drank less water and had lower urine osmolality as compared to the same strain housed in IVC

C57BL/6 mice had higher TEWL levels as compared to SCID, SKH and FVB mice that may reflect inflammatory skin phenotype

Temperature and humidity level measurements of the macroenvironment do not accurately reflect conditions within the cage.

TEWL measurements may be utilized in mice to allow for a better understanding of water turnover in mice


This work was supported by the Grants for Laboratory Animal Science (GLAS) program.

Special thanks to Joann Petty and Alisha Strong for their assistance with this project.

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