Oral leiomyosarcoma in a woodchuck (Marmota monax)

We report the case of a 4-year-old female woodchuck (Marmota monax) which presented with a white, firm and discrete mass in the hard palate. The mass extended into the oral cavity but it was well separated from the surrounding tissues. Histology of the tumor showed a malignant mesenchymal tumor with pleomorphic spindle cells varying in degrees of differentiation and density. The neoplastic cells had moderate amounts of granular or fibrillar eosinophilic cytoplasm with indistinct cell margins. Nuclei were oval to elongated and frequently blunt-ended with vesicular chromatin. Immunohistochemical study showed that the neoplastic cells expressed vimentin and alpha-smooth muscle actin but did not express desmin, pan-cytokeratin, and S-100. Therefore, histology and immunohistochemistry revealed that the tumor was oral leiomyosarcoma. Oral cavity is an extremely rare site for leiomyosarcoma and the present case is the first report of spontaneous oral leiomyosarcoma in animals.     

Microscopic anatomy of the skin of the woodchuck (Marmota monax): comparison of woodchuck hepatitis virus-infected and non-infected animals.

Thirty-three woodchucks were used in this study. Seventeen animals were healthy adults, not infected with woodchuck hepatitis virus (WHV); 10 were healthy adults infected with WHV; 4 were noninfected neonates; 2 were infected neonates. Within the 4 groups of woodchucks, no histologic differences were detected on the basis of sex or age. Neither were histologic findings different between infected and noninfected woodchucks of similar ages. The average thickness of skin (as measured from the skin surface to the inner limit of the dermis) from the general haired body area was 2394 microns. The skin was thickest on dorsal body areas, and gradually became thinner on ventral body and medial limb areas. The epidermis consisted of 4 layers: stratum basale, stratum spinosum, stratum granulosum, and stratum corneum. A stratum lucidum was present only in the epidermis of the footpads. There was no clear distinction between the superficial dermis and the deep dermis, except for the subtle differences in arrangement and size of collagen fibers. Elastic fibers were seen throughout the dermis, being more prominent in the superficial portion. Both compound and simple hair follicle arrangements were seen, with compound being more common. The arrectores pilorum muscles were largest in the skin over the dorsal body areas. Sebaceous glands were present either within the outer root sheath of hair follicles or in the dense connective tissue surrounding hair follicles. No apocrine sweat glands were found. However, there were abundant eccrine sweat glands in the subcutaneous fat of the footpads.     

Malignant pleural mesothelioma in a woodchuck (Marmota monax)

A spontaneous pleural mesothelioma was observed in a 4-year-old female woodchuck (Marmota monax). At necropsy, multifocal, tan to white, firm discrete nodules, 2 to 40 mm in diameter, were scattered over the ventral parts of the lungs and their corresponding parts of the diaphragm and the thoracic wall. Histopathologically, the tumor cells were large, cuboidal-shaped and variable size, and were weakly positive with PAS and Alcian blue. Immunohistochemically, neoplastic cells were positive for both vimentin and cytokeratin, indicating mesothelial origin. This report represents, as far as we know, the first reported case of a spontaneous mesothelioma in woodchucks.     

Chronic hepatitis and hepatocellular carcinoma associated with persistent woodchuck hepatitis virus infection

The livers of 16 woodchucks with naturally acquired chronic infection with woodchuck hepatitis virus were examined both grossly and histologically in 14 biopsy specimens and seven necropsy specimens. Fifteen woodchucks had lesions characteristic of chronic hepatitis; ten of these had chronic active hepatitis, four had chronic persistent hepatitis, and one had cirrhosis with nodular regeneration. In one woodchuck there was massive hepatic necrosis attributed to infection with an unclassified protozoan. Thirteen woodchucks had primary hepatocellular carcinoma. Metastasis to the lung was observed in only one woodchuck. These results were compared to liver lesions in 149 woodchuck hepatitis virus-negative woodchucks. Chronic hepatitis comparable to that associated with woodchuck hepatitis virus infection was not observed in woodchuck hepatitis virus-negative woodchucks although in one, a single, small hepatocellular adenoma was found.     

Scintigraphic diagnosis of primary hepatocellular carcinoma in the woodchuck (Marmota monax)

Hepatic imaging with 99mTc-sulfur colloid was used to diagnose primary hepatocellular carcinoma (PHC) in woodchucks infected with woodchuck hepatitis virus (WHV). Based on imaging results, 6 of 12 WHV-infected woodchucks had space-occupying hepatic lesions, and all 6 had PHC. Of the remaining woodchucks, 2 did not have PHC, 2 had discrete tumors (less than 1 cm diameter), 1 had miliary small tumors, and 1 had tumors located near the great vessels. Hepatic imaging was a valuable technique for diagnosis of PHC in WHV-infected woodchucks.     

Serologic survey of woodchuck hepatitis virus in North Carolina woodchucks (Marmota monax)

The prevalence of woodchuck hepatitis virus (WHV) in wild populations of woodchucks is understudied and therefore unclear. Although infection is common in the southeastern region of Pennsylvania and surrounding states, it is virtually absent in New York and New England. Sera were collected from wild woodchucks from Orange County, North Carolina and tested for the presence of markers of current or previous infection with WHV. Of the 24 woodchucks tested, there were three animals (12.5%) with WHV surface antigen as well as antibodies to woodchuck hepatitis core antigen in their serum, indicative of active infection. There were four (17%) animals with antibodies to WHV core antigen but no woodchuck hepatitis surface antigen, indicative of prior infections. The remaining 17 animals had no detectable markers of WHV infection. These data indicate that WHV is present in central North Carolina at rates approaching those seen in endemic areas, such as the mid-Atlantic region of the United States.     

Characterization of bioactive recombinant woodchuck interleukin-2 amplified by RLM-RACE and produced in eukaryotic expression system

Woodchucks (Marmota monax) infected with woodchuck hepatitis virus (WHV) represent a highly valuable laboratory model of hepatitis B virus (HBV) infection, in which molecular, immunological and pathological events occurring in infected humans are adequately reflected. To advance studies on T cell immune responses and propagation of hepadnavirus in T lymphocytes in this animal model, we determined the complete sequence of woodchuck interleukin-2 (wIL-2) cDNA by utilizing RNA ligase-mediated rapid amplification of cDNA ends (RLM-RACE) reaction. The wIL-2 sequence revealed a single open reading frame encoding for the predicted precursor protein comprised of a signal peptide and a 134 amino acid-long mature protein. The mature wIL-2 protein produced in the Escherichia coli expression system, designated as ec-rwIL-2, was found to be immunogenic but not biologically active. In contrast, precursor wIL-2 protein cloned into baculovirus transfer vector and expressed in Sf9 cells, designated as bac-rwIL-2, demonstrated functional competence. Further, bac-rwIL-2 was able to stimulate proliferation and to induce multiple daughter cell generations in woodchuck T cells, as well as facilitated the survival of standard IL-2-dependent mouse CTLL-2 cells in culture. Western blot analysis of bac-rwIL-2 using antibodies generated against ec-rwIL-2 revealed a single protein band of 15.5kDa. The availability of biologically active recombinant wIL-2 should facilitate ex vivo studies on functional competence of woodchuck T lymphocytes derived from different stages of hepadnaviral hepatitis and assist in recognizing their contribution to the pathogenesis of liver injury in the woodchuck model of hepatitis B.     

Hip luxation in a woodchuck (Marmota monax): successful treatment by closed reduction and a modified Ehmer sling.

An elastic tape sling successfully maintained reduction of a craniodorsal right coxofemoral luxation in a woodchuck (Marmota monax). No complications were encountered during the 14 days that the sling was in place. The animal remained normal through the following 8 mo.     

Skin disorders of the laboratory woodchuck (Marmota monax): a retrospective study of 113 cases (1980-1990).

An 11-year retrospective study was conducted on the dermatoses occurring in 113 woodchucks from a colony at the College of Veterinary Medicine at Cornell University. Bacterial dermatitis was the most common dermatologic disorder, accounting for 70.2% of the cases. The highest incidence of bacterial dermatitis occurred in September/October prior to hibernation and in February/March during the breeding season. Other dermatoses observed during the study period included Taenia crassiceps infection, microfilarial dermatitis, telogen defluxion, various neoplastic and hyperplastic lesions, and various neonatal conditions associated with trauma and/or bacterial infection. No association was found between any of these dermatoses and the presence of woodchuck hepatitis virus infection.     

Direct immunofluorescence testing of haired skin, nasal planum, and footpads of clinically normal woodchuck hepatitis virus-infected and non-infected woodchucks

The purpose of this study was to determine the frequency of immunoreactant deposition in the skin, footpad, and nasal planum of 10 clinically normal, non WHV-infected woodchucks. The second part of the study investigated the frequency of immunoreactant deposition at the same sites in clinically normal, WHV-infected woodchucks, and compared these results with those reported in humans. Direct immunofluorescence testing of the haired skin, footpad, and nasal planum of all normal and 9 of the 10 WHV-infected woodchucks was negative. The footpad of 1 WHV-infected woodchuck revealed immunoreactant deposition in the walls of the superficial dermal blood vessels.     

Direct immunofluorescence testing for immunoglobulin deposits in haired skin, nasal planum and footpads of woodchuck hepatitis virus-infected woodchucks with chronic hepatitis and multiple hepatocellular carcinomas.

The purpose of this study was to determine the frequency of immunoglobulin deposition in the haired skin, footpads, and nasal planums of 10 WHV-infected woodchucks with chronic hepatitis and hepatocellular carcinoma and compare these results with those reported in humans. Immunoglobulin deposition was detected in the skin samples of 3 of 10 woodchucks. Granular deposits were revealed in the superficial dermal blood vessels of the nasal planum, lateral thoracic skin, and footpads in 1 animal each. In 1 of these animals, (lateral thorax) immunoglobulin deposition was concurrently present at the basement membrane zone.