Sathya K. Chinnadurai

Initial Case Reports of Cancer in Naked Mole-rats (Heterocephalus glaber).

Naked mole-rats (NMRs; Heterocephalus glaber) are highly adapted, eusocial rodents renowned for their extreme longevity and resistance to cancer. Because cancer has not been formally described in this species, NMRs have been increasingly utilized as an animal model in aging and cancer research. We previously reported the occurrence of several age-related diseases, including putative pre-neoplastic lesions, in zoo-housed NMR colonies. Here, we report for the first time 2 cases of cancer in zoo-housed NMRs. In Case No. 1, we observed a subcutaneous mass in the axillary region of a 22-year-old male NMR, with histologic, immunohistochemical (pancytokeratin positive, rare p63 immunolabeling, and smooth muscle actin negative), and ultrastructural characteristics of an adenocarcinoma possibly of mammary or salivary origin. In Case No. 2, we observed a densely cellular, poorly demarcated gastric mass of polygonal cells arranged in nests with positive immunolabeling for synaptophysin and chromogranin indicative of a neuroendocrine carcinoma in an approximately 20-year-old male NMR. We also include a brief discussion of other proliferative growths and pre-cancerous lesions diagnosed in 1 zoo colony. Although these case reports do not alter the longstanding observation of cancer resistance, they do raise questions about the scope of cancer resistance and the interpretation of biomedical studies in this model. These reports also highlight the benefit of long-term disease investigations in zoo-housed populations to better understand naturally occurring disease processes in species used as models in biomedical research.

PHARMACOKINETICS OF A SINGLE SUBCUTANEOUS DOSE OF SUSTAINED RELEASE BUPRENORPHINE IN NORTHERN ELEPHANT SEALS (MIROUNGA ANGUSTIROSTRIS)

Abstract:u2003 Information regarding analgesics in pinnipeds is limited. This study aimed to establish the pharmacokinetic parameters of a single subcutaneous dose of sustained release buprenorphine (Buprenorphine SR®) in juvenile northern elephant seals (Mirounga angustirostris) with regard to its potential to provide long-lasting analgesia that requires infrequent dosing. Seals (n = 26) were administered a single dose of sustained release buprenorphine at 0.12 mg/kg s.c. Blood samples were collected from the extradural intervertebral vein at 0 hr and at three or four of the following time points: 0.5, 1, 2, 6, 12, 24, 36, 48, 60, 96, 120, and 144 hr. Seals were examined daily for systemic and local adverse reactions. Plasma was analyzed by liquid chromatography tandem–mass spectrometry for buprenorphine and norbuprenorphine concentrations. A noncompartmental analysis for pharmacokinetic parameters was calculated using standard methods and equations. An average maximum concentration of 1.21 ng/ml (0.3–2.9 ng/ml) was detected 12 hr postadministration. Concentrations were quantifiable up to 144 hr postadministration but were below those expected to provide analgesia in some other species. No systemic adverse effects were noted in healthy seals receiving sustained release buprenorphine. Cellulitis or abscesses at the injection site were observed in 6/26 (23%) seals between 24 and 168 hr postadministration. Adverse local effects suggest that this drug should be used with caution in northern elephant seals.

The minimum alveolar concentration of sevoflurane in ring-tailed lemurs (Lemur catta) and aye-ayes (Daubentonia madagascariensis).

OBJECTIVEnTo determine the minimum alveolar concentration (MAC) of sevoflurane for ring-tailed lemurs (Lemur catta) and aye-ayes (Daubentonia madagascariensis).nnnSTUDY DESIGNnProspective experimental trial.nnnANIMALSnSix adult ring-tailed lemurs, aged 1.3-11.2xa0years (median age: 8.26) and weighing a meanxa0±xa0standard deviation (SD) of 2283xa0±xa0254xa0g. Five adult aye-ayes, aged 4.4-19.3xa0years (median age: 8.0) and weighing 2712xa0±xa0191xa0g.nnnMETHODSnMinimum alveolar concentration of sevoflurane was determined using a tail-clamp stimulus. The end-tidal sevoflurane (FeSevo) concentration was increased or decreased by approximately 10% after a positive or negative response to tail clamping, respectively. This procedure was repeated until a positive and negative result were seen on two consecutive trials (i.e. a negative result was achieved and a single 10% decrease in FeSevo concentration resulted in a positive test). The MAC for that animal was determined to be the mean of the concentrations at the two consecutive trials.nnnRESULTSnThe meanxa0±xa0SD MAC of sevoflurane for ring-tailed lemurs was 3.48xa0±xa00.55% and 1.84xa0±xa00.17 for aye-ayes. This represents a 47.1% higher MAC in ring-tailed lemurs compared to aye-ayes.nnnCONCLUSIONS AND CLINICAL RELEVANCEnThe sevoflurane MAC was significantly higher in ring-tailed lemurs, compared to aye-ayes. The MAC of sevoflurane in aye-ayes is consistent with reported MAC values in other species. Extrapolation of sevoflurane anesthetic dose between different species of lemurs could lead to significant errors in anesthetic dosing.

HYPERCALCEMIA AND METASTATIC MINERALIZATION INVOLVING FOOTPADS IN ROCK HYRAXES (PROCAVIA CAPENSIS)

Abstract:u2003 Three rock hyraxes (Procavia capensis) maintained in a zoological collection had chronic hypercalcemia and azotemia. In addition, all animals displayed signs of lameness due to footpad lesions that were histologically characterized as marked metastatic mineralization with granulomatous inflammation, reminiscent of calcinosis circumscripta. Although the animals were managed with aggressive fluid therapy, calciuresis, and dietary modification, all were eventually humanely euthanized due to the severity of their footpad lesions and/or progression of renal disease. Metastatic mineralization was also noted in other soft tissues among the three cases, including the stomach, colon, lung, vascular wall, ovary, and kidney. Varying degrees of interstitial nephritis were confirmed on postmortem examination, and in the absence of other causes for hypercalcemia, metastatic mineralization was presumably the consequence renal dysfunction. The renal pathway is the primary mode of calcium excretion in the rock hyrax. In renal dysfunction, hypercalcemia may develop secondary to decreased calcium excretion. Footpad mineralization is an uncommon sequel to renal dysfunction in domestic animals but has not been reported in rock hyraxes. A retrospective review of mortality data in this collection revealed a notable prevalence of renal lesions, including two additional animals with metastatic mineralization and renal dysfunction. Expanding knowledge of renal diseases will further guide preventative and clinical measures, including screening for metastatic mineralization and therapeutic trials for management of hypercalcemia and calcium mineral deposition in the footpads and other soft tissues.

Treatment of mandibular osteomyelitis in two red-necked wallabies (Macropus rufogriseus) by means of intensive long-term parenteral drug administration and serial computed tomographic monitoring

CASE DESCRIPTION 2 female red-necked wallabies (Macropus rufogriseus) were evaluated because of sudden-onset mandibular swelling, ptyalism, and hyporexia. CLINICAL FINDINGS Physical examination revealed a mandibular swelling with a fluctuant center in both wallabies. Hematologic analysis revealed leukocytosis with a mature neutrophilia and monocytosis in one wallaby (case 1) and a slight neutrophilia, hyperglobulinemia, and high serum alanine aminotransferase activity in the other (case 2). Cytologic examination of the swelling revealed a uniform population of gram-negative rods in case 1 and neutrophilic inflammation in case 2. Radiography revealed a soft tissue mandibular swelling with osteolucency around mandibular incisor roots in both wallabies. Computed tomography revealed changes consistent with chronic active mandibular osteomyelitis and reactive bone formation, but also sequestra formation not appreciable via radiography. TREATMENT AND OUTCOME Long-term antimicrobial treatment was initiated with clindamycin (17 to 21 mg/kg [7.7 to 9.5 mg/lb], IV, q 12 h for 40 to 55 days) and high-dose benzathine penicillin G (80,000 U/kg [36,364 U/lb], SC, q 12 h for 150 days). Serial CT was performed to evaluate response to treatment and resolution of disease. A CT scan 18 months after the initial evaluation revealed complete resolution of osteomyelitis and sequestra. CLINICAL RELEVANCE Advanced imaging and long-term treatment and management were integral to the successful outcome for these wallabies, given that the osseous changes visible on CT images were not visible on standard radiographs, guiding therapeutic decision-making. This report provides new therapeutic and diagnostic monitoring information to assist clinicians with similar cases.

DISSEMINATED OPHIDIOMYCES OPHIODIICOLA INFECTION IN A CAPTIVE EASTERN MASSASAUGA (SISTRURUS CATENATUS CATENATUS)

Abstract An adult, captive-born eastern massasauga (Sistrurus catenatus catenatus) was examined for a subcutaneous abscess and fistula cranial to the vent. The wound improved initially with lavage and systemic antibiotic therapy, but multiple, scattered, small subcutaneous nodules later developed over the ventrum and lateral aspects of the body. Examination of fine needle aspirates from these nodules revealed granulomatous inflammation and fungal elements morphologically consistent with Ophidiomyces ophiodiicola. The animal died before antifungal therapy could be implemented. At necropsy, fungal granulomas were also present in the kidneys, liver, lung, air sac, ovary, and spleen. This case report describes an atypical presentation of systemic ophidiomycosis in a captive-born snake.

CANINE DISTEMPER IN A VACCINATED SNOW LEOPARD (PANTHERA UNCIA)

Abstract A 6-yr-old male snow leopard (Panthera uncia) presented with acute seizures, hyperthermia, and tachypnea. Because of a diagnosis of anuric renal failure, the animal was euthanized. On histopathologic examination, numerous intralesional intracytoplasmic and intranuclear inclusions were found in the lungs, lymph nodes, and stomach. Positive immunohistochemical staining for canine distemper virus (CDV) was found in the lungs and, to a lesser extent, in the lymph nodes and brain. Molecular testing yielded a CDV H gene sequence that was closely related to CDV isolates concurrently found in wild raccoons from adjacent forested areas. The leopard had been vaccinated once against CDV with the use of a recombinant canarypox-vectored live vaccine during a routine wellness examination 12 wk prior to death. Serial serum neutralization titers performed on banked serum collected between vaccination and death showed poor serologic response to the vaccine. This case demonstrates a probable failure of protection against naturally occurring CDV.

Response to “Regarding Mole-rats and Cancer”

My coauthors and I thank Welsh and Traum for their interest in our reports of cancer in naked mole-rats (NMRs) and their thoughts regarding potential mechanisms of carcinogenesis in these 2 cases. With these limited cases, it is arduous to determine exact mechanisms of cancer development in this seemingly cancer-resistant species. However, we are delighted that our publications have generated more scientific discussion and inquiry about these unique rodents and their role as animal models for aging and cancer studies. In fact, another paper was recently published documenting 4 additional cases of cancer in a different zoo colony. The oxygen levels within the NMR exhibits were tested and are consistent with levels found in ambient air (*21%; FiO2 readings: 20.8%–20.9%). Therefore, there is no evidence of long-standing or intermittent hypoxia in these zoo environments. As such, there are no mechanisms to decrease oxygen levels in these NMR exhibits, which are the same as indicated in the standard husbandry practices for NMRs in research laboratories. Several other parameters for NMR husbandry must be strictly adhered to for successful maintenance, social order, and breeding of NMRs in captivity. Questions have arisen regarding the habitat conditions and husbandry and breeding practices at the zoologic institutions from which these 2 NMRs came, specifically in comparison with research settings. This is particularly interesting as, to date, there have been no official reports of cancer in research NMRs. Zoologic institutions follow established guidelines based on the natural history and behavior of wild NMRs, to ensure the optimal health and well-being of these zoo colonies. Of note, these husbandry standards and practices are virtually identical to those published for NMRs in research settings, with the exception of burrow designs and aesthetics, as the purposes differ: exhibition of animals versus production of animals. Specific habitat factors include temperature (82 F–87 F), humidity (30%–50%), illumination (minimal, no direct sunlight), and space with interconnecting tubes and specialized ‘‘burrow’’ compartments, including a nursery and latrine. Zoo NMRs maintain a eusocial hierarchy, with 1 breeding queen, several breeding males, and both male and female nonreproductive workers. Recently, new husbandry techniques have been introduced to improve neonatal NMR survival in research laboratories to increase colony productivity. The described diets of NMRs in zoo and research settings are similar and aim to maintain healthy gut flora and dentition, cecotrophy behaviors, and adequate enrichment. One important difference between research NMRs and zoohoused NMRs is routine and thorough disease surveillance. While research NMRs are monitored for clinical or gross disease, data are limited on the histologic lesions of these colonies. Notably, we found several microscopic diseases in our retrospective study of zoo NMRs that were overtly healthy and carrying out normal behaviors and eusocial lifestyles, including breeding. Furthermore, the gastric tumor in case No. 2 from our report was so small as to not be discernable grossly and was detected only microscopically. Thus, this cancer would have gone undiagnosed if complete histologic evaluation had not taken place. Zoo-housed NMR colonies are treated like all other zoo fauna and receive systematic diagnostic workups to determine causes of morbidity and mortality, to optimize care and treatments of future cases, to learn more about health and disease in various species, and to improve conservation efforts of species in their natural environments. Our report of cancer in 2 NMRs does not detract from their profound resistance to carcinogenesis; however, it does highlight the importance of examining the entire animal at the gross and microscopic levels to rule out the presence of neoplastic disease.

Prothrombin time and activated partial thromboplastin time using a point-of-care analyser (Abaxis VSpro®) in Bennett's wallabies (Macropus rufogriseus).

There are few reports of coagulation times in marsupial species. Blood samples collected from 14 Bennetts wallabies (Macropus rufogriseus) under anaesthesia during routine health assessments were analysed for prothrombin time (PT) and activated partial thromboplastin time (aPTT) using a point-of-care analyser (POC) (Abaxis VSPro®). The wallabies had an aPTT mean of 78.09u2009s and median of 78.1u2009s. The PT for all wallabies was greater than 35u2009s, exceeding the longest time measured on the POC. Although PT was significantly longer, aPTT was similar to the manufacturers domestic canine reference range.