Four-toed hedgehogs presented bloody stool and loss of appetite. Integumental masses were observed in two of the four cases. Intraabdominal masses were observed on radiographs and ultrasonography in the remaining two cases. The masses were surgically removed from all four cases. All samples were histologically and immunohistochemically consistent with histiocytic sarcoma (HS). At the time of surgery, 3 of 4 cases had grossly recognized metastatic/disseminated lesions. Survival time was 48 days, 64 days, and 113 days, respectively, and the remaining case is currently alive (at Day 207). The present report describes the clinical management and outcome of hedgehogs that were diagnosed with HS.

A 56-mo-old male guinea pig (Cavia porcellus) presented with gradual weight loss from 757 to 691 g during the preceding month. Cardiac-specific diagnostics detected decreased cardiac contractility, moderate cardiomegaly, pericardial effusion, and pulmonary edema. At 1 mo after presentation, the guinea pig died while under treatment. Necropsy revealed a 5 × 3 × 3-mm, tan, smooth nodule on the base of the heart. On histology, the nodule contained moderately cellular neoplastic tissue comprising cuboidal cells arranged in variably sized follicles. Immunohistochemically, the neoplastic cells were positive for thyroglobulin and thyroid transcription factor 1, consistent with ectopic thyroid carcinoma. Other significant histologic lesions included thyroid adenoma of the right thyroid gland, myocardial hypertrophy and degeneration, suppurative bronchopneumonia, and centrilobular hepatocellular degeneration. Although serum total thyroxine concentration was not evaluated, we considered that the tumors in this case were functional because concurrent lesions related to hyperthyroidism were present. In guinea pigs, reports of endocrine tumors, including thyroid tumors, have been increasing. To our knowledge, the current report represents the first documentation of ectopic thyroid carcinoma in this species.

We describe a case of primary localized histiocytic sarcoma of the lumbar vertebrae in a four-toed hedgehog. The case showed aggressive osteolysis of lumbar vertebrae on radiography, and a soft-tissue mass effacing this region was noted, suggesting a neoplastic lesion. No metastatic lesions were apparent. Antemortem diagnosis was challenging, and necropsy was performed. Histopathological and immunohistochemical findings were consistent with localized histiocytic sarcoma. This report provides documentation of the clinical and pathologic features of an unusual form of histiocytic sarcoma localizing to lumbar vertebrae in a four-toed hedgehog.

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Previous reports of leukemia in hedgehogs are limited. We describe clinicopathologic features of leukemia in 9 hedgehogs, including eosinophilic leukemia (n = 3) and acute leukemia/leukemic phase of lymphoma (n = 6). All 3 hedgehogs with eosinophilic leukemia were older than 2 years of age; in contrast, 4 of 6 cases of acute leukemia/lymphoma were <2 years old. Hedgehogs presented for non-specific clinical signs of anorexia and lethargy. On hematologic testing, hedgehogs with eosinophilic leukemia had a marked leukocytosis, consisting mostly of eosinophilic precursors with fewer mature eosinophils, whereas there were 43-97% immature cells (blasts) in the blood of hedgehogs with acute leukemia/lymphoma. Anemia (n = 6) and/or thrombocytopenia (n = 6) were concurrent findings. Increased liver enzyme activities (alanine aminotransferase, alkaline phosphatase) and hypoalbuminemia were the common findings on biochemical panels. All cases of eosinophilic leukemia and 4 cases of acute leukemia/lymphoma died shortly after diagnosis (median 7 days, range 0-41 days), whereas 2 cases of acute leukemia/lymphoma lived for 94 or 101 days. Postmortem examination in 5 cases (1 eosinophilic leukemia, 4 acute leukemia/lymphoma) showed bone marrow infiltrates, confirming eosinophilic leukemia and acute leukemia in 1 and 3 cases, and bone marrow necrosis in 1 animal with acute leukemia/lymphoma. Immunohistochemical staining of bone marrow sections confirmed a T-cell acute leukemia in 1 case. Several hedgehogs had concurrent carcinomas. Hedgehogs suffer from eosinophilic leukemia and acute leukemia/lymphoma. However, classification of acute leukemia by lineage was not possible due to lack of hedgehog cross-reactive or species-specific reagents.

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Two vascular tumors in two Argentine horned frogs (Ceratophrys ornata) are described. Case 1 involved a 7-year-1-month-old Argentine horned frog that had a splenic mass with a sanguineous coelomic effusion. Histologically, the splenic parenchyma was effaced by a poorly-demarcated, invasive mass, consisting of spindle cells with marked nuclear atypia forming irregular blood vessel channels containing blood. Case 2 involved a pedunculated facial mass located at the upper right lip of an over-8-month-old Argentine horned frog. Histologically, the well-demarcated, poorly cellular mass consisted of sparse proliferation of spindle cells forming irregular slits with prominent edema. Immunohistochemically, the neoplastic cells of both cases were positive for anti-CD31 antibody. The diagnoses were hemangiosarcoma in case 1 and lymphangioma in case 2. To the best of the authors’ knowledge, this is the first description of neoplastic diseases in captive Argentine horned frogs.

Skin lesions possibly caused by Papillomavirus infections in two four-toed hedgehogs are described. In case 1, there was a papillary mass on the right hind limb. Histologically, the mass was consistent with viral papillomas. In the other case, multifocal papillary masses with erosions and ulcers were found throughout the body, mainly on the extremities. Histology showed continuative lesions composed of acanthosis, Bowenoid in situ carcinoma, and squamous cell carcinoma, with abrupt transitions between the lesions. In both cases, keratinocytes in the granular layer infrequently had features of koilocytes and intranuclear inclusion bodies, and immunohistochemical staining was positive for anti-human papillomavirus antibody. To the best of the authors' knowledge, this is the first pathological documentation of possibly papillomavirus-associated skin lesions in four-toed hedgehogs.