Central nervous system mycobacteriosis caused by Mycobacterium genavense in degus (Octodon degus).

Degus (Octodon degus) that were kept at a breeding facility presented with neurological or respiratory symptoms and died. Necropsies were performed on 9 individuals, and no significant gross lesions were found. Histologically, spinal cord necrosis was observed in all 9 cases and granulomatous myelitis in 5 of the 9 cases. Locally extensive necrosis of the brain and encephalitis were observed in 7 of the 9 cases. Acid-fast bacteria were found in the spinal cords, brains, and lungs from all 9 cases. Immunohistochemically, Mycobacterium tuberculosis antigen was observed in the spinal cords, brains, and lungs from all 9 cases. Double-labeling immunofluorescence revealed M. tuberculosis antigen in IBA1- and myeloperoxidase-immunopositive cells. Extracted genomic DNA from 8 of the 9 cases was successfully amplified with the primers for Mycobacterium genavense ITS1 and hypothetical 21 kDa protein genes, and the polymerase chain reaction products were identified as M. genavense by DNA sequencing. This report highlights the susceptibility of degus to M. genavense infection in the central nervous system.

Hamster polyomavirus-associated T-cell lymphomas in Syrian hamsters (Mesocricetus auratus).

Hamster polyomavirus (HaPyV) infection has been associated with lymphomas in Syrian hamsters. In the present study, 14 cases of lymphoma in pet Syrian hamsters were pathologically examined and the involvement of HaPyV was investigated. Among 14 cases, 11 were abdominal and 3 were cutaneous lymphomas. The average ages of hamsters with abdominal lymphoma and cutaneous lymphoma were 7 months (range: 4-12 months) and 14 months (range: 6-23 months), respectively. Histologically, abdominal lymphomas were characterized by the diffuse growth of tumor cells with intermediate or large nuclei, low mitotic rates, the presence of tingible body macrophages, and the T-cell immunophenotype. Furthermore, 4/11 abdominal lymphomas were immunopositive for T-cell intracellular antigen-1, suggesting cytotoxic T-cell lymphomas. Cutaneous lymphomas were diagnosed as nonepitheliotropic T-cell lymphoma. Polymerase chain reaction (PCR) detected HaPyV DNA in 12/14 samples, and a sequence analysis of PCR amplicons confirmed >99% nucleotide identity to the published HaPyV sequences. In situ hybridization (ISH) for HaPyV DNA resulted in diffuse nuclear signals within tumor cells in 10/14 cases. Consistent with previous findings, all HaPyV-associated lymphomas were observed in the abdominal cavity of young hamsters. Polymerase chain reaction and ISH were useful for identifying the involvement of HaPyV in lymphomas, and ISH results indicated the presence of episomal HaPyV in neoplastic lymphocytes. The present study suggests that HaPyV infection is highly involved in abdominal lymphomas in young pet Syrian hamsters in Japan and provides diagnostic information on HaPyV-associated lymphoma.

A histopathological study on adrenal cysts in ferrets.

Adrenal disorders are common in ferrets, but there are few studies on cystic lesions of the adrenal gland. The present study describes pathological and immunohistochemical features of adrenal cysts in eleven ferrets and discusses their histogenesis. In nine of eleven cases examined, which included seven, one, and one right, left, and bilateral cases, respectively, cysts were in the adrenal cortex and lined with epithelial cells. These epithelial cells contained an Alcian blue-negative/PAS-positive material and were positive for cytokeratin (CK) 7. The staining pattern was similar to that of biliary epithelial cells in the ferret. In five of the cases, there were small ducts adjacent to the cysts that were positive for CK7 and CK20 and negative for CK19. Based on the anatomical proximity between the right adrenal and liver, the immunohistochemical features of the small duct cells were comparable to those of hepatic oval cells. These results indicate the possibility that these adrenocortical cysts in the ferret originated from the biliary system. In the other two cases, the cysts lacked an epithelial cell lining, and there were dilated lymphoid vessels around the cysts. These cysts were assumed to have developed in the adrenal medulla, because the cyst wall was positive for glial fibrillary acidic protein and there were adrenal medullary cells positive for synaptophysin in the cyst wall. Therefore, the medullary cysts may have been associated with dilated vasculatures.

Proliferative Lesions of the Endometrium of 50 Four-Toed Hedgehogs ( Atelerix albiventris).

Uteri from 50 four-toed hedgehogs ( Atelerix albiventris) with clinical signs of uterine disease were histopathologically examined. Sixteen animals (32%) were diagnosed with endometrial hyperplasia, 7 animals (14%) were diagnosed with endometrial polyp, and 27 animals (54%) were diagnosed with endometrial neoplasia. The mean ages of the animals with endometrial hyperplasia, polyp, and neoplasia were 28.7 months, 29.4 months, and 25.2 months, respectively. The neoplasms were classified into 7 endometrial mixed tumors, 12 endometrial stromal nodules, and 8 endometrial stromal sarcomas. However, the endometrial stromal nodules and endometrial stromal sarcomas often developed within or were contiguous with an endometrial polyp or mixed tumor. Interestingly, the stromal tumors and the stromal components of the endometrial polyp and mixed tumor displayed extraendometrial differentiation (eg, into adipocytes, granular cells, smooth muscle cells, and osteoid tissue). The endometrial stromal sarcomas exhibited severe cellular atypia and invaded subendometrial tissue. Immunohistochemical examinations demonstrated that the stromal cells of the hyperplastic lesions as well as the neoplastic lesions were positive for CD10, the progesterone receptor, and Wilms tumor 1. The four-toed hedgehog develops unique uterine neoplasms that are mainly composed of endometrial stromal cells and probably arise from endometrial polyps and/or mixed tumors.

Molecular evidence of Sarcocystis species in captive snakes in Japan.

Sarcocystis nesbitti, using snakes as the definitive host, is a causative agent of acute human muscular sarcocystosis in Malaysia. Therefore, it is important to explore the distribution and prevalence of S. nesbitti in snakes. Nevertheless, epizootiological information of S. nesbitti in snakes remains insufficient because few surveys have assessed Sarcocystis infection in snakes in endemic countries. In Japan, snakes are popular exotic pet animals that are imported from overseas, but the degree of Sarcocystis infection in them remains unclear. The possibility exists that muscular sarcocystosis by S. nesbitti occurs in contact with captive snakes in non-endemic countries. For a total of 125 snake faecal samples from 67 snake species collected at animal hospitals, pet shops and a zoo, this study investigated the presence of Sarcocystis using polymerase chain reaction (PCR) for the 18S ribosomal RNA gene (18S rDNA). Four (3.2%) faecal samples were positive by PCR. Phylogenetic analysis of the 18S rDNA sequences obtained from four amplification products revealed one isolate from a beauty snake (Elaphe taeniura), Sarcocystis zuoi, which uses rat snakes as the definitive host. The isolate from a Macklot's python (Liasis mackloti) was closely related with unidentified Sarcocystis sp. from reticulated pythons in Malaysia. The remaining two isolates from tree boas (Corallus spp.) were closely related with Sarcocystis lacertae, Sarcocystis gallotiae and unidentified Sarcocystis sp. from smooth snakes, Tenerife lizards and European shrews, respectively. This report is the first of a study examining the distribution of Sarcocystis species in captive snakes in Japan.

A retrospective study on subcutaneous malignant peripheral nerve sheath tumors in 14 domestic rabbits (Oryctolagus cuniculus) treated surgically between 2008 and 2021.

A retrospective study involving 14 pet rabbits histopathologically diagnosed with malignant peripheral nerve sheath tumors (MPNSTs) was conducted. The age at diagnosis was 4-12 years, with a median age of 8.6 years. All rabbits had solid subcutaneous tumor masses in varied locations. Surgical excision of the tumors was performed in all cases. Recurrence was observed in 10 cases (71%), and postoperative metastasis to the lung was suspected in 4 cases (29%). The postoperative mean and median survival times were 11 months and 9 months, respectively. Hence, MPNSTs should be considered in the differential diagnosis for subcutaneous masses in rabbits and it is essential to inform the owners of the potentially high recurrence and metastasis rates.

Histological and immunohistochemical features of cutaneous mast cell tumor in six captive four-toed hedgehogs (Atelerix albiventris).

This report described the histopathological and immunohistochemical features of cutaneous mast cell tumor (MCT) in six hedgehogs. The hedgehogs presented single cutaneous mass with ulcer and crusting. Histologically, the neoplastic lesions were characterized by the proliferation of well-differentiated mast cells (3 cases), and atypical mast cells (3 cases) with one atypical histiocytic morphology. Immunohistochemically, tumor cells were positive for KIT and mast cell tryptase, and were negative for Iba-1. In well-differentiated MCT, all patients were clinically improved and survived more than 365 days after surgical excision, whereas an atypical histiocytic MCT showed aggressive behavior with re-recurrence, and the animal died 115 days after surgery. These findings suggest that, compatible with other animals, well-differentiated MCT has a better prognosis in hedgehogs.

Influenza A Virus Infection in Domestic Ferrets.

Ferrets are animals that are known to be susceptible to influenza A virus (IAV) infection. To evaluate the risk of IAV transmission from diseased ferrets to humans, a survey was performed to detect specific antibodies against the H1, H3, H5, and H7 subtypes of IAV. Using enzyme-linked immunosorbent assay for hemagglutinin proteins, we found a high positive rate for the H1 (24.1%) and H3 (5.2%) subtypes. The results were confirmed by a virus neutralization test for representative antibody-positive serum samples. We also detected hemagglutinin and neuraminidase genes in two ferrets showing acute respiratory disease and whose owner was diagnosed with IAV infection; a human H1N1pdm virus was isolated from one of these ferrets. Our findings suggest that attention should be paid to IAV infection from humans to ferrets and vice versa.

Survey of tortoises with urolithiasis in Japan.

Urolithiasis is a disease often seen in tortoises at veterinary hospitals, however there have been no comprehensive research reports of tortoises with urolithiasis in Japan. In this study, we analyzed tortoises diagnosed with urolithiasis at three domestic veterinary hospitals. Based on medical records, we assessed the diagnostic method, species, sex, body weight, dietary history, husbandry, clinical signs, clinical examination, treatment for urolithiasis, and clinical outcome. The total number of cases in the 3 facilities was 101. As for species of tortoises, the most common was the African spurred tortoise (Centrochelys sulcata) with 42 cases (41.6%), followed by the Indian star tortoise (Geochelone elegans) with 30 cases (29.7%). Six other species were confirmed to have calculi. Almost all cases (99 cases, 98%) had a single calculus, and only 2 had multiple calculi. The prevalence of urolithiasis for the total number of tortoises having visited to one institution during the same period was 5.1%. Of the 86 cases that underwent calculi removal, 64 (74.4%) were successfully removed via the vent, and the efficacy of this method was confirmed. Nineteen cases (22%) were approached via plastronotomy, among which only 2 died postoperatively. In this study, we could not clarify the relationship between calculi formation and diets or other husbandry factors.

Granulosa cell tumor in 8 African pygmy hedgehogs (Atelerix albiventris).

A retrospective study involving eight African pygmy hedgehogs histopathologically diagnosed with granulosa cell tumors was conducted. The age at onset was 2.2-4.5 years, with a median age of 3.6 years. The most common clinical signs were hematuria and abdominal distension, which were observed in >50% cases. Exploratory laparotomy was performed in all cases, and ovariohysterectomy or excision of the abdominal mass was performed. Patients with only hematuria survived for >250 days after surgery, whereas those with initial ascites showed recurrence of ascites or tumor growth and survived for approximately 130 days after surgery. Intraperitoneal injection of carboplatin was performed in three recurrent cases. In one of these three cases, the tumor mass disappeared. Hence, carboplatin can be considered a potential antineoplastic drug for the treatment of granulosa cell tumors.

Pathological and Immunohistochemical Findings of Disseminated Histiocytic Sarcoma in a Sugar Glider (Petaurus breviceps).

A 6-year-old intact female sugar glider (Petaurus breviceps) had a swelling at the pouch region and died 8 days after presentation. At necropsy, the urinary bladder and abdominal lymph nodes were enlarged and a mass was located in the pericloacal region. Tumour infiltration was also observed in the medial iliac lymph nodes, liver, spleen, small intestine, uterus and left ovary. Histopathologically, the tumours were composed of pleomorphic histiocytes that had round or bizarre nuclei and abundant pale eosinophilic cytoplasm. Immunohistochemically, tumour cells were positive for ionized calcium-binding adaptor molecule 1 and human leukocyte antigen and negative for CD3, B lymphocyte antigen 36 and cytokeratin. Histopathological and immunohistochemical examinations confirmed a diagnosis of disseminated histiocytic sarcoma. This neoplasm has not been previously reported in a sugar glider.

Neuroblastoma of the adrenal gland in a ferret.

A 5-year-old castrated male ferret was referred for hind limb paresis and subcutaneous mass at the lumber area. Based on clinical examination including computed tomography, extension of the mass to the abdominal cavity was confirmed. An exploratory laparotomy revealed that the mass at the cranial area of the left kidney extended dorsally to the vertebra and to the subcutis. The excised mass was histologically diagnosed as a medullary tumor of the adrenal gland, and some neoplastic cells were beta III-tubulin-, doublecortin- and neurofilament-positive. Based on these findings, the tumor was considered to be a neuroblastoma.

Spontaneous cutaneous mast cell tumor with lymph node metastasis in a Richardson's ground squirrel (Spermophilus richardsonii).

A 4-year-old female Richardson's ground squirrel (Spermophilus richardsonii) presented with multicentric nodules arising from the skin of the middle of the tail and lumbosacral regions. Histologically, the nodules were composed of a proliferation of spindloid to pleomorphic cells that sometimes formed sheets and fascicular to storiform patterns. Diffuse infiltration of eosinophils was also noted. The results of immunohistochemistry indicated positive labeling for vimentin, mast cell tryptase, c-kit, and Ki-67. Toluidine blue stain revealed fine, metachromatic, cytoplasmic granules. The histologic diagnosis was mast cell tumor. The neoplasm recurred and metastasized to the right lumbar lymph node 1 month later.

Neoplasitic diseases in ferrets in Japan: a questionnaire study for 2000 to 2005.

The objective of this study was to collect epidemiological data on neoplasms in pet ferrets in Japan. A questionnaire to collect information was made available to Japanese veterinary practitioners through the web site of the Japanese Society of Exotic Pet Medicine. Completed questionnaires were returned from 29 practices, and 945 neoplasms met the criteria for inclusion in the study. Neoplasms were found in every organ system except the respiratory system; the endocrine (418; 44.2%), integumentary (196; 20.7%) and hemolymphatic (184; 19.5%) systems were most commonly affected. The most common tumor types were pancreatic islet cell tumor (211: 22.3%), adrenal gland tumor (207; 21.9%) and lymphoma (152; 16.1%). The age of the affected ferrets ranged from less than 3 months to more than 7 years of age. Tumor incidence was highest in ferrets between 4 and 6 years of age. No sex predilection was found. These results were similar to those recently published in North America. Most Japanese pet ferrets are imported from North America, and their husbandry including diets is similar to that in North America, which may explain the similar tendencies in the incidence of neoplasms in this study and those of findings in North America.

Exotic Mammal Orthopedics.

Orthopedic disorders are a common clinical presentation for the exotic clinician. Before treating the fracture it is vital to stabilize the patient. Small exotic mammals are characterized by relatively thinner bones, adding to the difficulty the small size already represents. A combination of conservative and surgical treatment options are available. The principles of orthopedic surgery and ideas behind the treatment options remain the same as for small mammals, but not all techniques can be directly extrapolated. Historically, the tie-in fixator has been the preferred surgical choice whenever feasible, but further development in bone plates represents a promising advancement.

Adrenal diseases in ferrets in Japan.

Adrenal diseases are quite common in Japanese pet ferrets; however, there have been no reports concerning the epidemiology of ferret adrenal disease in Japan. The purpose of this study was to collect epidemiological data on ferret adrenal disease in Japan by sending a questionnaire to veterinarians throughout Japan. Among the 521 cases that met the criteria for this study, 307 were adrenocortical carcinoma (58.9%), 117 were adrenocortical adenoma (22.5%) and 87 were adrenocortical hyperplasia (16.7%), respectively. Sex, clinical signs, concurrent diseases, age and the sites of the affected adrenal gland in these cases were similar to those reported in North America. Most pet ferrets in Japan are imported from North America, and their husbandry in Japan is similar to that in North America, which may be the cause of the similarity in ferret adrenal disease between North America and Japan. Because a difference in the incidence of ferret adrenal diseases among countries has been reported, further research is necessary to investigate the factors related to the similarities and how to decrease the incidence of adrenal diseases in ferrets in Japan.

Ostium secundum type of atrial septal defect in a rabbit.

A 14-month-old, female mini rex was referred for a detailed examination because of exercise intolerance with associated dyspnea. The thoracic radiograph demonstrated severe cardiac enlargement and elevation of the trachea. The echocardiography revealed dilatations of the right-side heart and pulmonary artery, and the color flow Doppler echocardiography demonstrated an atrial septum defect with left to right shunt, resulting in a disturbed flow. The rabbit died 19 days after the initial presentation, and a necropsy was performed. At the necropsy, a defect, 5 mm in diameter, was detected in the atrial septum. Based on the location of the defect, an ostium secundum type atrial septal defect was diagnosed. This is the first clinical report of atrial septal defect in rabbits.

Neuromastoma of the hard palate mucosa in an Australian green tree frog (Litoria caerulea).

A hard palate mass was surgically removed from an Australian green tree frog (Litoria caerulea) and examined pathologically. The tumor consisted of sheets of small cells arranged in a tubular structure and cords or rosettes with fibrovascular stroma. Immunohistochemically, neoplastic cells were diffusely positive for cytokeratin and neuron-specific enolase and partially positive for S-100 and doublecortin. These findings indicate that the tumor originated from the neuroectodermal tissue. Based on these findings, the tumor was classified as a neuromastoma (neuroepithelioma). Sensory cells located in the hard palate of the frog were considered to be the origin of the tumor. The frog died after going through 3 surgeries and experiencing difficulties closing its mouth.

Anaplastic large T-cell lymphoma in three black-tailed prairie dogs (Cynomys ludovicianus).

Anaplastic large T-cell lymphoma (ALTCL) is rarely reported in domestic animals. Accordingly, the histopathological and immunohistochemical characteristics of ALTCL have not been well established in prairie dogs. The present report documents three cases in which prairie dogs were diagnosed with ALTCL arising in the subcutaneous tissue, oral mucosa or the mesenteric lymph nodes. Of the three cases, one was available for necropsy and the others were biopsy cases. Microscopically, moderate to large, pleomorphic neoplastic lymphocytes with ovoid to polygonal, bizarre-shaped nuclei, abundant cytoplasm and eosinophilic granules were seen in all cases. Immunohistochemical staining revealed membranous or cytoplasmic CD3 expression of the neoplastic lymphocytes. The neoplastic cells often had granzyme B-positive cytoplasmic granules. One of the prairie dogs with nodal ALTCL suffered systemic dissemination of the tumor and died suddenly. In the two biopsy cases, one animal died on the day of the biopsy examination and the other died six weeks after chemotherapy. ALTCL in prairie dogs displays a cytotoxic T cell phenotype and presumably carries a poor prognosis regardless of the anatomical type.

Spontaneous lymphoma in a prairie dog (Cynomys ludovicianus).

A 4-year-old, female, black-tailed prairie dog (Cynomys ludovicianus) was examined for acute dyspnea and two skin masses. Tentative diagnosis of lymphoma was made based on cytology of pleural effusion and the skin masses. Administration of prednisolone was initially effective in improving the condition; however, the clinical signs deteriorated after radiation therapy and administration of cyclophosphamide. Postmortem examination revealed that neoplastic lymphocytes had infiltrated most of the organs, and the histopathological diagnosis was multi-centric lymphoma.