The rapid growth of the aging human population highlights the need for laboratory animal models to study the basic biologic processes of aging and susceptibility to disease, drugs, and environmental pollutants. Methods are needed to evaluate the health of aging animals over time, particularly methods for efficiently monitoring large research colonies. Here we describe an observational assessment method that scores appearance, posture, mobility, and muscle tone on a 5-point scale that can be completed in about 1 min. A score of 1 indicates no deterioration, whereas a score of 5 indicates severe deterioration. Tests were applied to male Brown Norway rats between 12 and 36 mo of age (n = 32). The rats were participating concurrently in experiments on the behavioral effects of intermittent exposure (approximately every 4 mo) to short-acting environmental chemicals. Results demonstrated that aging-related signs of deterioration did not appear before 18 mo of age. Assessment scores and variability then increased with age. Body weights increased until approximately 24 mo, then remained stable, but decreased after 31 mo for the few remaining rats. The incidence of death increased slightly from 20 to 28 mo of age and then rose sharply; median survival age was approximately 30 mo, with a maximum of 36 mo. The results indicate that our observational assessment method supports efficient monitoring of the health of aging rats and may be useful in studies on susceptibility to diseases, drugs, and toxicants during old age.

Pharmacokinetics of enrofloxacin, a fluoroquinolone antibiotic, was determined in adult female Xenopus laevis after single-dose administration (10 mg/kg) by intramuscular or subcutaneous injection. Frogs were evaluated at various time points until 8 h after injection. Plasma was analyzed for antibiotic concentration levels by HPLC. We computed pharmacokinetic parameters by using noncompartmental analysis of the pooled concentrations (naive pooled samples). After intramuscular administration of enrofloxacin, the half-life was 5.32 h, concentration maximum was 10.85 μg/mL, distribution volume was 841.96 mL/kg, and area under the time–concentration curve was 57.59 μg×h/mL; after subcutaneous administration these parameters were 4.08 h, 9.76 μg/mL, 915.85 mL/kg, and 47.42 μg×h/mL, respectively. According to plasma pharmacokinetics, Xenopus seem to metabolize enrofloxacin in a manner similar to mammals: low levels of the enrofloxacin metabolite, ciprofloxacin, were detected in the frogs' habitat water and plasma. At necropsy, there were no gross or histologic signs of toxicity after single-dose administration; toxicity was not evaluated for repeated dosing. The plasma concentrations reached levels considered effective against common aquatic pathogens and suggest that a single, once-daily dose would be a reasonable regimen to consider when treating sick frogs. The treatment of sick frogs should be based on specific microbiologic identification of the pathogen and on antibiotic susceptibility testing.

Cefovecin sodium is a third-generation broad-spectrum cephalosporin antibiotic licensed for the treatment of skin infections in cats and dogs. The objective of our study was to assess whether its pharmacokinetic profile in squirrel monkey, rhesus macaques, and cynomolgus macaques was similar to that of dogs. Plasma levels were determined by using protein precipitation followed by liquid chromatography tandem mass spectrometry. After subcutaneous dosing at 8 mg/kg, the plasma terminal half-life of cefovecin was substantially shorter in the nonhuman primates (2.6 to 8.0 h) than in dogs (102 h). The total plasma exposure (AUC_0-96h) was 10- to 40-fold lower in nonhuman primate species. In cynomolgus macaques, cefovecin showed a similar subcutaneous bioavailability (82% compared with 100%) and volume of distribution (0.16 compared with 0.12 L/kg) as compared to dogs; however, the plasma clearance of cefovecin was 20-fold higher. Cefovecin susceptibility testing and minimum inhibitory concentrations were not established for clinical isolates in nonhuman primates. However, if the minimum inhibitory concentrations of cefovecin for various nonhuman primates pathogens are in the same range as those observed for canine pathogens, our results suggest that cefovecin used at the same dosing regimen and frequency prescribed for the dogs will be ineffective and that increases in dose or frequency (or both) may be required.

Sheep (Ovis aries) are increasingly used at our institution as models of human disease. Within the research environment, routine husbandry and handling of sheep has potential for transmission of zoonotic agents, including Giardia. The prevalence of Giardia in sheep may approach 68%. Classic diagnostic testing involves microscopic examination for fecal cysts or trophozoites; however, limitations of microscopy include time, labor, and potential false-negative results due to intermittent shedding. We wished to determine whether a commercial rapid ELISA used for Giardia detection in dogs and cats could be used in sheep. Fecal samples collected from sheep (n = 93) were tested with a combination of 6 methods: reference laboratory fecal flotation, reference laboratory ELISA, inhouse fecal flotation, and commercially available tests (enzyme immunoassay, direct fluorescence antibody assay, and rapid ELISA). Prevalence of Giardia infection in facility sheep was 11.8% (11 of 93 animals). Of the 11 samples considered positive, 3 were confirmed by multiple testing methods, and 5 were positive by microscopy alone. Inhouse fecal flotation for 8 samples was positive on only 1 of 2 consecutive testing days. The rapid ELISA test exhibited 0% sensitivity for sheep giardiasis. Overall, the examined methods had low sensitivities and low positive predictive values. Despite limitations, microscopic analysis of repeat fecal samples remained the most accurate diagnostic method for ovine giardiasis among the methods tested.

We undertook establishing an SPF baboon colony in response to requests from researchers. To enable the widest possible future use of SPF baboons, our aim was to develop an SPF colony of baboons (Papio hamadryas anubis) free of 12 target viruses: 5 herpesviruses, 4 retroviruses, simian virus 40, measles, and monkeypox. Infant baboons were removed from their mothers within 24 h of birth and nursery-reared. Groups of 3 to 8 age-matched conspecifics were isolated in separate rooms for 1 y while undergoing repeated testing for target viruses. During the initial 7 y of the SPF program, 171 infants were enrolled, of which 76 (44.4%) subsequently were removed from the program. Of those removed, 54 (71.0%) were culled due to breaks in virus-free status, 12 (15.8%) died of various causes, 4 (5.3%) developed seizures, and 6 (7.9%) were removed for other reasons. The most problematic viruses were baboon cytomegalovirus (25.9% of culls), Herpesvirus papio 1 (51.9%), and simian foamy virus (7.4%). Using conspecific groups of 3 to 4 infants reduced first-year program losses as compared with groups of 6 to 8. There have been 17 births in the SPF colony, and all these infants have been free of all target viruses since birth. On the basis of these results, early removal of infants from their dams, housing in small peer groups, frequent virus testing, and aggressive culling of virus-positive animals is an effective approach for development of a baboon colony free of multiple viruses.

Pinworms are highly contagious parasites of laboratory rodents that often are treated with fenbendazole. To our knowledge, the effect of fenbendazole at therapeutic dosages on behavioral tests in mice has not been evaluated. Here we studied 6-wk-old male C57BL/6N mice. We compared the behavior of control mice (fed regular diet) with 3 groups of mice treated with dietary fenbendazole. Treatment groups were 4 wk of fenbendazole, 2 wk of fenbendazole followed by 2 wk of regular diet, and 2 wk of regular diet followed by 2 wk of fenbendazole. At the end of dietary treatment all groups were tested by open field for central, peripheral and vertical activity; elevated plus maze for anxiety; and rotarod for motor ability and then evaluated by clinical pathology and selected histopathology. Treated and control groups showed no differences in open field or elevated plus maze testing, histopathology, or clinical pathology. However mice treated for 4 wk with fenbendazole or 2 wk of fenbendazole followed by 2 wk regular diet stayed on the rotarod for shorter periods than did controls, and mice treated with 2 wk of regular diet followed by 2 wk fenbendazole showed a trend toward shorter rotarod times. In light of this study, we suggest that open field and elevated plus maze testing is unlikely to be affected by 4 wk fenbendazole treatment in male C57BL/6 mice; however, behavioral tests of motor ability such as rotarod tests may be affected during and for at least 2 wk after fenbendazole treatment.

The mouse is the most commonly used laboratory animal, accounting for up to 80% of all mammals used in research studies. Because rodents generally are group-housed, an efficient system of uniquely identifying individual animals for use in research studies, breeding, and proper colony management is required. Several temporary and permanent methods (for example, ear punching and toe clipping) are available for labeling research mice and other small animals, each with advantages and disadvantages. This report describes a new radiofrequency identification tagging method that uses 500-μm, light-activated microtransponders implanted subcutaneously into the ear or tail of mice. The preferred location for implanting is in the side of the tail, because implantation at this site was simple to perform and was associated with shorter implantation times (average, 53 versus 325 s) and a higher success rate (98% versus 50%) compared with the ear. The main benefits of using light-activated microtransponders over other identification methods, including other radiofrequency identification tags, is their small size, which minimizes stress to the animals during implantation and low cost due to their one-piece (monolithic) design. In addition, the implantation procedure uses a custom-designed 21-gauge needle injector and does not require anesthetization of the mice. We conclude that this method allows improved identification and management of laboratory mice.

Rodent surgeries in biomedical research facilities are often performed in series. This practice presents many challenges to maintaining aseptic technique between animals. Here, we examined using soaking in 70% isopropyl alcohol for aerobic bacterial decontamination of surgical instruments and gloves used in a series of as many as 10 mouse laparotomy surgeries. These surgeries were performed on mice that were euthanized immediately prior to the procedure. Instruments and gloves were cultured before and after each procedure to determine the presence of aerobic bacterial contamination. To assess the efficacy of the decontamination protocol, culture results were grouped by procedure and then paired (before soak and after soak) for analysis using McNemar test at an α level of 0.05. In addition, by using the Fisher exact test, this modified aseptic method was compared with strict aseptic technique, for which autoclaved instruments and sterile surgical gloves were used for each procedure. In this study, we observed that the modified aseptic technique using 70% isopropyl alcohol soaks pre- vented aerobic bacterial contamination of instruments and gloves for as many as 5 mice.

Provided is the surgical procedure for ligating the left circumflex coronary artery to simulate heart ischemia by using a rabbit model. Heart rate monitored by electrocardiogram was increased at 5 min after ligation (mean ± SEM, 205 ± 13 bpm) when compared with that before ligation (170 ± 12 bpm), but returned to baseline at 25 min after ligation (183 ± 11 bpm). A marked elevation in the ST segment and reduction of the QRS wave of the electrocardiogram indicated the evolving myocardial infarct. The ejection fraction derived from MRI was decreased by 20% in the infarcted heart. The extent of necrosis and fibrosis in the myocardium due to ischemia led to decreased compliance and efficiency of the left ventricle. Masson trichrome staining showed blue-stained fibrils with the appearance of loose, threadlike scar tissue dispersed transmurally in the left ventricle and extending toward the apex. This study demonstrates the feasibility of MRI analysis of myocardial infarction in a rabbit model. The myocardial architecture, including the geometry of the myofibers which determines the contractile function of the heart, is clearly demonstrated by using cardiac MRI. Understanding the 3-dimensional arrangement of the myocardial microstructure and how remodeling of the infarcted myocardium affects cardiac function in an animal model has important implications for the study of heart disease in humans.

Assessment of pain in rabbits is challenging, and studies of effective surgical analgesia are lacking for this species. Seeking potential indicators of postoperative pain, we performed ovariohysterectomy and telemeter placement as a form of moderate surgical injury in 20 female rabbits. Rabbits were assigned to 1 of 4 treatment groups (5 per group): buprenorphine (0.02 mg/kg SC every 12 h for 3 d); fentanyl (25-μg patch placed 24 h preoperatively); ketoprofen (1 mg/kg SC every 24 h for 3 d), and control (no treatment given). Various physiologic and behavioral variables were recorded by blinded observers, including food and water consumption, fecal output, and remotely recorded behaviors during daily exercise in 1.2 × 1.8 m floor pens. Compared with preoperative values, significant declines occurred in: food consumption (days 1 to 7), water consumption (days 1 to 4), fecal output (days 1 to 2), mean travel distance, and rearing (days 1 to 3 and day 7). No single treatment proved significantly better than another. Our results demonstrate substantial inappetance and reduction of normal activity levels in rabbits after surgery. Although results from rabbits treated with empirical doses (those typically recommended) of analgesics did not appear substantially better than those from the untreated control group, comparison of other doses and multimodal analgesic techniques by using these behavioral monitoring strategies may prove useful in future studies aimed at optimizing postoperative analgesia in rabbits.

The aim of our study was to compare the electrocardiographic recordings in an experimental open-chest swine model before and after left-sided thoracotomy to detect any surgery-induced fluctuations that might interfere with subsequent experimental interventions. We obtained electrocardiograms from 8 deeply anesthetized domestic swine and compared the respective ST-segment potentials obtained after vascular surgery and after left-sided thoracotomy and dissection of the left anterior descending coronary artery. Compared with baseline recordings, no significant ST-segment deviation on any of the electrocardiographic leads occurred after vascular surgery. However, statistically significant ST-segment depression was observed after thoracotomy. Invasive surgical procedures in open-chest swine models may lead to morphologic changes in the ST segment. The physiologic mechanism of these changes is not fully understood.

Pancreatic islet cell adenoma, oral squamous cell carcinoma, peripheral polyneuropathy, and multiple age-associated degenerative lesions were diagnosed in an aged Sprague–Dawley rat presenting with polyuria, polydypsia, dehydration, anorexia, weight loss, and posterior weakness. Microscopically, the islet cell adenoma was encapsulated by fibrous tissue and composed of packets of oval-to-polygonal monomorphic cells in a fibrovascular stroma. Immunohistochemically, the majority of cells within the mass expressed insulin. In light of the histologic and immunohistochemical findings, a diagnosis of insulinoma was made. The oral squamous cell carcinoma, grossly presenting as gingival ulceration, was composed of nests and cords of squamous epithelial cells that focally eroded and infiltrated the hard palate and resulted in degeneration of the maxillary nerve. The peripheral polyneuropathic lesions were characterized by extensive axonal degeneration and microangiopathic changes that were highly suggestive of a hypoglycemic etiopathogenesis secondary to insulinoma.

We here describe a case of recurrent gingival enlargement in an olive baboon (Papio anubis). This baboon (a male breeder that had not undergone any experimental procedures) also had shown mild gingival enlargement the 2 y prior to the current lesion. Clinical and histopathologic findings confirmed a diagnosis of idiopathic gingival enlargement.

An 8.5-mo-old female rhesus macaque was examined for an apparent lump on the right arm, below the elbow. The macaque showed no signs of pain or discomfort. Examination revealed that the lump was actually a bend in the forearm. Radiography demonstrated that some of the long bones of the animal were bowed. Differential diagnoses included rickets, hyperparathyroidism, pseudohyperparathyroidism, and a growth dysplasia. No other similar abnormalities in animals from that cage or any other enclosure in our large colony were observed. Blood chemistries and a complete hemogram were within normal limits for a macaque of this age. Serum was submitted for a vitamin D profile that included assays for parathyroid hormone, 25-hydroxyvitamin D, and ionized calcium. Serum samples from sex- and age-matched normal controls were sent for comparison and to establish a baseline profile. The affected animal had vitamin D levels comparable to unaffected controls. Bone biopsies appeared normal for a macaque of this age. Fluorine levels in the drinking water supply were within acceptable limits. Consistent with the information available, a diagnosis of idiopathic camptomelia, or bowing of the long bones, was made. In humans, developmental camptomelia is associated with several bone dysplasias in infants and children. These conditions are thought to be caused by genetic mutations in enzymes or transcription factors that control development of the epiphyses and are almost always associated with other lethal and nonlethal developmental abnormalities.

A 15-y-old male rhesus macaque with a 3-d history of labored breathing, was culled from a nonhuman primate research colony after thoracic radiographs and exploratory surgery revealed a 10-cm, well-circumscribed space-occupying mass in the posterior thoracic cavity. The multilobulated cystic and necrotic neoplasm was composed of interlacing streams and fascicles of neoplastic spindle cells arranged in Antoni A, and less commonly, Antoni B patterns. Verocay bodies were present also. The neoplasm was encapsulated mostly, and histomorphologic features were benign. Immunohistochemistry indicated that neoplastic cells were positive for vimentin, S100, glial fibrillary acidic protein, and nerve growth factor receptor. Reticulin histochemical staining and immunohistochemical stains for collagen IV and laminin showed a prominent basal lamina surrounding the neoplastic cells. The histologic features and results of the immunohistochemical stains confirmed peripheral nerve origin and were consistent with schwannoma. To our knowledge, this is the first case of thoracic schwannoma in a rhesus macaque and the second reported case of schwannoma in a nonhuman primate.

Two pair-housed, 1-y-old common marmosets (Callithrix jacchus) had intermittent loose feces and weight loss for approximately 2 mo. Cryptosporidum parvum was identified by ELISA in the feces of both animals. CBC and blood chemistry values, including liver enzymes, were within normal range. Both marmosets were treated with the antibiotic paromomycin (15 mg/kg PO) twice daily for 28 d. Resolution of clinical signs coincided with treatment. Three follow-up samples, taken 2 wk apart after treatment was finished, were negative for cryptosporidium ELISA in both animals. Paromomycin should be considered for treatment of cryptosporidiosis in marmosets.