THE MANAGEMENT OF LYMPHOPROLIFERATIVE NEOPLASIA IN FOUR NORTHERN SEA OTTERS (ENHYDRA LUTRIS KENYONI)

Lymphoproliferative neoplasia has been reported in both free-ranging sea otters and those in managed care, but little information is available on the management of this neoplastic disease in this species. This case series describes clinical lymphoma in four northern sea otters (Enhydra lutris kenyoni) in managed care. Two otters presented with Stage 5 lymphoma with evidence of hematologic spread resulting in leukemia. Two additional otters presented with Stage 3 disease. Immunophenotypes in these cases included disseminated large B-cell lymphoma and lymphoblastic lymphoma of potential T-cell origin. Cases were managed with multiagent chemotherapy protocols including prednisone, L-asparaginase, cyclophosphamide, vincristine, cytosine arabinoside, lomustine, and doxorubicin. Unique approaches included the use of a vascular access port in one case and development of an autologous vaccine in another. Survival time ranged from 81 to 409 days. Diagnosis, staging, and treatment with multiagent protocols is recommended for the management of lymphoma in sea otters.

Coagulation Disorders, Testing, and Treatment in Exotic Animal Critical Care

Despite poor recognition in the literature, exotic companion animals are affected by many diseases that can result in disordered coagulation and fibrinolysis. This article outlines current knowledge of hemostasis, common diagnostic tests and reviews reported diseases associated with coagulopathy in small mammals, bird and reptiles. A range of conditions affect platelets and thrombocytes, endothelium and blood vessels, and plasma clotting factors. Improved recognition and monitoring of hemostatic disorders will enable targeted therapy and improved case outcomes.

Development of renal adenocarcinoma in a ferret with renal cortical cysts (Mustela putorius furo)

CASE DESCRIPTION

A 5.5-year-old 0.929-kg spayed female domestic ferret (Mustela putorius furo) underwent serial abdominal ultrasonographic and clinicopathologic examinations after multiple renal cysts were detected bilaterally during a routine examination.

CLINICAL FINDINGS

The ferret was apparently healthy at the start of the monitoring period and had no clinical signs for > 20 months. Four months after the initial examination, the largest cyst became increasingly mineralized; 17 months after detection, it had increased in size and become amorphous, and the ferret's plasma BUN concentration was mildly high. Within 21 months after the first visit, a nodule was detectable, and hydronephrosis developed in the kidney with the largest cyst. Findings for fine-needle aspirates from the nodule were consistent with renal carcinoma.

TREATMENT AND OUTCOME

Contrast-enhanced CT revealed severe unilateral nephromegaly with no contrast uptake in the affected ureter. Following surgical removal of the affected kidney, histologic examination identified renal adenocarcinoma replacing the entire renal cortex and medulla. The ferret was euthanized postoperatively because of declining condition. On necropsy, metastasis to a mesenteric lymph node was identified; comorbidities included 2 other neoplasms and acute, severe injury of the contralateral kidney.

CLINICAL RELEVANCE

Neoplastic transformation of a renal cyst was suspected in the ferret of this report on the basis of observed ultrasonographic changes over time and extensive infiltration of the neoplasm throughout the affected kidney. Renal cysts are linked to renal neoplasia in other species, and the findings for this patient supported the need for periodic monitoring of renal cysts in ferrets.

Systemic Anaplastic Large T-Cell Lymphoma with Initial Presentation of Dysuria in a Dog

A 6-year-old spayed female Akita Dog had dysuria, severe urinary retention and miliary masses in the vagina. Computed tomography revealed a mass at the urethrovaginal junction. The dog died 2 months after initial presentation. At necropsy, the urethrovaginal mass was greyish‒white, solid and 9 × 6 × 6 cm in size with circumferential thickening of the urethral wall. Multiple whitish nodules were seen in the visceral organs and skin. Histopathologically, the urethrovaginal mass comprised a diffuse population of medium-sized to large round neoplastic cells with ovoid to bean-shaped nuclei and eosinophilic cytoplasm. Aberrantly large neoplastic cells with eccentric, horseshoe-shaped or irregularly-shaped nuclei and abundant eosinophilic cytoplasm resembled 'hallmark cells' of human anaplastic large cell lymphoma. Similar neoplastic lesions were present in all the grossly visible masses. Neoplastic cells were diffusely immunopositive for CD3 and occasionally for CD30 and granzyme B. On the basis of the clinical, pathological and immunohistochemical findings, the case was diagnosed as systemic anaplastic large cell lymphoma arising from the lower urinary tract.

Pathology of Diseases of Geriatric Exotic Mammals

The review covers select disease conditions most frequently described in aging rodents (rats, mice, hamsters, guinea pigs), rabbits, and ferrets. The conditions are categorized by general organ systems, infectious diseases, and neoplasms. Two data systems, the Veterinary Medical Teaching Hospital and Comparative Pathology Laboratory at the University of California, Davis and Zoo/Exotic Pathology Service, Citrus Heights, California were used in the determining disease conditions to describe.

Subclinical BCG-osis in a Captive Badger (Meles meles) with Lymphoma

Subclinical systemic dissemination of Bacillus Calmette-Guérin (BCG) is described in a captive badger (Meles meles) with lymphoma. An adult female European badger was vaccinated per os with BCG and after 8 weeks post-mortem examination identified marked lymphadenomegaly and multinodular hepatic lesions. The histopathology and immunohistochemistry confirmed a multicentric T-cell lymphoma, associated with high BCG bacterial load in numerous tissues. The histology did not identify BCG-associated lesions. The scenario suggested that the T-cell lymphoma likely favoured the dissemination of the BCG ('BCG-osis'). Given that lymphoma is rare in badgers, this neoplasm should not interfere with the efficacy of large-scale vaccination programmes.

Neoplasia in Ferrets

Neoplasia is a common cause of disease in domestic ferrets worldwide. The most common neoplasms are islet cell tumors (insulinoma), adrenocortical neoplasms, and lymphoma. The definitive etiology has yet to be defined, but husbandry, genetic predisposition and infectious agents are postulated causes. Definitive diagnosis requires sampling and microscopic analysis of the neoplasm, but initial testing including blood, urine and diagnostic imaging can aid the diagnostic process. Based on the type of tumor and its location, therapeutic options include surgery, chemotherapy and radiation therapy. Numerous chemotherapeutic protocols and drugs have been published for the use in ferrets and a ferret specific formula for calculating body surface area has been established. In addition to the more commonly affected endocrine and hemolymphatic systems, ferrets can also develop tumors in the skin and subcutis, gastrointestinal and reproductive tracts, musculoskeletal, nervous, urinary, respiratory and vascular systems.

Evidence-Based Advances in Ferret Medicine

This literature review covers approximately 35 years of veterinary medicine. This article develops the current state of knowledge in pet ferret medicine regarding the most common diseases according to evidence-based data and gives insight into further axis of research. Literature review was conducted through identification of keywords (title + ferret) with Web-based database searching. To appreciate the methodological quality and the level of evidence of each article included in the review, full-text versions were reviewed and questions addressed in the articles were formulated. Analysis of the articles' content was performed by the authors, and relevant clinical information was extracted.

Ferret Oncology: Diseases, Diagnostics, and Therapeutics

Neoplastic disease is common in ferrets. Approximately half of all tumors diagnosed in ferrets are located in the endocrine or hemolymphatic system. Many factors may influence the choice of treatment. Medical management of adrenal tumors has a greater disease-free period compared to adrenalectomy. In ferrets with an insulinoma, no difference is seen in the mean survival time of medically and surgically treated patients. Aside from medical and surgical treatment modalities, chemotherapy and radiation therapy have also been described in ferrets in other types of tumors. The outcome of these treatment modalities is not always favorable.

Histological and immunohistochemical features of histiocytic sarcoma in four domestic ferrets (Mustela putorius furo)

Four cases of histiocytic sarcoma in domestic ferrets (Mustela putorius furo) are described in the present study. Tumor samples obtained from the abdominal viscera, including the spleen, were submitted for histologic examination. Microscopically, poorly demarcated masses contained numerous round- to pleomorphic-shaped cells with coarsely vacuolated and eosinophilic cytoplasm. Bizarre, binucleated tumor cells and multinucleated giant tumor cells with low phagocytic activity were commonly observed. Immunohistochemically, tumor cells in all of the cases were positive for vimentin, human leukocyte antigen-DR, ionized calcium-binding adapter molecule-1, and lysozyme, but some of them lacked cluster of differentiation (CD)163 or CD208 expression. The survival time after surgical resection was 9 days to 5 months. Histiocytic sarcoma in the ferret is a rare, but highly aggressive, tumor commonly found in the spleen.

Histology and immunohistochemistry of severe inflammatory bowel disease versus lymphoma in the ferret (Mustela putorius furo)

Inflammatory bowel disease (IBD) is a common disorder of ferrets ( Mustela putorius furo) that may progress to lymphoma. Although routine histology is used to distinguish between these diseases, misclassifications may occur. Immunohistochemistry (IHC) is commonly used to distinguish between IBD and lymphoma in small animals. The objective of our study was to determine the agreement in the diagnosis reached solely using hematoxylin and eosin (HE)-stained, full-thickness sections versus using a combination of HE and IHC. Enteric sections from 44 ferrets previously diagnosed with IBD or intestinal lymphoma and 3 control ferrets were analyzed by pathologists with expertise in ferrets. A pathologist blinded to the original diagnosis assessed the same HE-stained sections. Analysis was then repeated using HE sections in parallel with sections stained using antibodies against CD3 and CD79a. No significant difference was found between the original HE diagnosis and the HE diagnosis reached by the blinded pathologist ( p = 0.91) or between the blinded pathologist’s HE versus HE with IHC diagnosis ( p = 0.16). In the 2 cases where disagreement was present, IHC was pivotal in reaching a final diagnosis. There was no significant age ( p = 0.29) difference between diagnoses; however, significantly more male ferrets were affected with IBD than females ( p = 0.004). Immunophenotype of the lymphoma was not correlated with predilection for location in the intestinal wall ( p = 0.44). Results suggest that although IHC is not necessary to distinguish IBD from intestinal lymphoma in ferrets, it can be useful a definitive diagnosis in cases of severe IBD.

Development of ferret as a human lung cancer model by injecting 4-(Nmethyl-N-nitrosamino)-1-(3-pyridyl)-1-butanone (NNK)

OBJECTIVE

Development of new animal lung cancer models that are relevant to human lung carcino-genesis is important for lung cancer research. Previously we have shown the induction of lung tumor in ferrets (Mustela putorius furo) exposed to both tobacco smoke and a tobacco carcinogen (4-(N-methyl-N-nitrosamino)-1-(3-pyridyl)-1-butanone, NNK). In the present study, we investigated whether NNK treatment alone induces both preneoplastic and neoplastic lesions in the lungs of ferrets.

METHODS

We exposed ferrets to NNK by i.p. injection of NNK (50 mg/kg BW) once a month for four consecutive months and then followed up for 24, 26 and 32 weeks. The incidences of pulmonary pre-neoplastic and neoplastic lesions were assessed by histopathological examination. The expressions of 7 nicotinic acetylcholine receptor ( 7 nAChR, which has been shown to promote lung carcinogenesis)and its related molecular biomarkers in lungs were examined by immunohistochemistry and/or Western blotting analysis.

RESULTS

Ferrets exposed to NNK alone developed both preneoplastic lesions (squamous metaplasia, dysplasia and atypical adenomatous hyperplasia) and tumors (squamous cell carcinoma, adenocarcinoma and adenosquamous carcinoma), which are commonly seen in humans. The incidence of tumor induced by NNK was time-dependent in the ferrets (16.7%, 40.0% and 66.7% for 24, 26 and 32 weeks, respectively). 7 nAChR is highly expressed in the ferret bronchial/bronchiolar epithelial cells, and alveolar macrophages in ferrets exposed to NNK, and in both squamous cell carcinoma and adenocarcinoma of the ferrets. In addition, we observed the tendency for an increase in phospho-ERK and cyclin D1 protein levels (p = 0.081 and 0.080, respectively) in the lungs of ferrets exposed to NNK.

CONCLUSION

The development of both preneoplastic and neoplastic lesions in ferret lungs by injecting NNK alone provides a simple and highly relevant non-rodent model for studying biomarkers/molecular targets for the prevention, detection and treatment of lung carcinogenesis in humans.

Immune System Cells in Healthy Ferrets

The ferret has emerged as an excellent animal model to characterize several physiologic and pathologic conditions. The distribution and characterization of different types of immune system cells were studied in healthy ferret tissues. Eight primary antibodies were tested for immunohistochemistry in formalin-fixed tissues: anti-CD3, anti-CD79α, anti-CD20, anti-HLA-DR, anti-lysozyme, anti-CD163, anti-SWC3, and anti-Mac387. The anti-CD3 antibody labeled T cells mainly in interfollicular and paracortical areas of lymph nodes, cortex and thymic medulla, and periarteriolar lymphoid sheaths in the spleen. The anti-CD79α and anti-CD20 antibodies immunolabeled B cells located in lymphoid follicles at lymph nodes, spleen, and Peyer patches. The CD79α and CD20 antibodies also labeled cells with nonlymphoid morphology in atypical B-cell locations. The anti-HLA-DR antibody labeled macrophages, some populations of B and T lymphocytes, and different populations of dendritic cells in lymph nodes, Peyer patches, spleen, and thymus. The anti-lysozyme antibody immunolabeled macrophages in the liver, lymph nodes, spleen, and thymus. The Mac-387, CD163, and SWC3 antibodies did not show any positive reaction in formalin-fixed or frozen tissues. To elucidate the origin of the uncommon CD79α/CD20 positive cells, a double immunohistochemistry was carried out using the anti-HLA-DR + the anti-CD79α, the anti-HLA-DR + the anti-CD20, and the anti-lysozyme + the anti-CD79α antibodies. Double labeling was mainly observed when the anti-HLA-DR + the anti-CD79α antibodies were combined. The immunohistologic characterization and distribution of these immune system cells in healthy ferret tissues should be of value in future comparative studies of diseases in ferrets.

Imaging findings in 14 domestic ferrets (Mustela putorius furo) with lymphoma

Lymphoma is the most common malignant neoplasia in domestic ferrets, Mustela putorius furo. However, imaging findings in ferrets with lymphoma have primarily been described in single case reports. The purpose of this retrospective study was to describe imaging findings in a group of ferrets with confirmed lymphoma. Medical records were searched between 2002 and 2012. A total of 14 ferrets were included. Radiographs (n = 12), ultrasound (n = 14), computed tomography (CT; n = 1), and magnetic resonance imaging (MRI; n = 1) images were available for review. Median age at the time of diagnosis was 5.2 years (range 3.25–7.6 years). Clinical signs were predominantly nonspecific (8/14). The time between the first imaging study and lymphoma diagnosis was 1 day or less in most ferrets (12). Imaging lesions were predominantly detected in the abdomen, and most frequently included intra‐abdominal lymphadenopathy (12/14), splenomegaly (8/14), and peritoneal effusion (11/14). Lymphadenopathy and mass lesions were typically hypoechoic on ultrasound. Mild peritoneal effusion was the only detected abnormality in two ferrets. Mild pleural effusion was the most common thoracic abnormality (3/12). Expansile lytic lesions were present in the vertebrae of two ferrets with T3‐L3 myelopathy and the femur in a ferret with lameness. Hyperattenuating, enhancing masses with secondary spinal cord compression were associated with vertebral lysis in CT images of one ferret. The MRI study in one ferret with myelopathy was inconclusive. Findings indicated that imaging characteristics of lymphoma in ferrets are similar to those previously reported in dogs, cats, and humans.

Gastrointestinal Disease in Exotic Small Mammals

Exotic small mammal medicine is a relatively new specialty area within veterinary medicine. Ferrets, rabbits, and rodents have long been used as animal models in human medical research investigations, resulting in a body of basic anatomic and physiologic information that can be used by veterinarians treating these species. Unfortunately, there is a paucity of veterinary articles that describe clinical presentation, diagnosis, and treatment options of gastrointestinal (GI) disease as it affects exotic small mammals. Although there is little reference material relating to exotic small mammal GI disease, patients are commonly presented to veterinary hospitals with digestive tract disorders. This article provides the latest information available for GI disease in ferrets (Helicobacter mustelae gastritis, inflammatory bowel disease [IBD], GI lymphoma, systemic coronavirus, coccidiosis, and liver disease), rabbits (GI motility disorders, liver lobe torsion, astrovirus, and coccidiosis), guinea pigs (gastric dilatation volvulus [GDV]), rats (Taenia taeniaeformis), and hamsters (Clostridium difficile). Both noninfectious diseases and emerging infectious diseases are reviewed as well as the most up-to-date diagnostics and treatment options.

α-Enolase, an adhesion-related factor of Mycoplasma bovis

Mycoplasma bovis is the causative agent of Mycoplasma bovis-associated disease (MbAD). Although the mechanisms underlying M. bovis adherence to host cells is not clear, recent studies have shown that the cell surface protein α-enolase facilitates bacterial invasion and dissemination in the infected host. In this study, we cloned, expressed and purified recombinant M. bovis α-enolase and induced polyclonal anti-α-enolase antibodies in rabbits. M. bovis α-enolase was detected in the cytoplasmic and membrane protein fractions by these antibodies. Triple immunofluorescence labeling combined with confocal laser scanning microscopy (CLSM) revealed that the plasminogen (Plg) enhanced the adherence of M. bovis to embryonic bovine lung (EBL) cells; the values obtained for adherence and inhibition are consistent with this finding. Interestingly, we found that trace amounts of trypsin acted as a more effective enhancer of cell adherence than Plg. Hence, our data indicate that surface-associated M. bovis α-enolase is an adhesion-related factor of M. bovis that contributes to adherence by binding Plg.

Clinical and pathologic characteristics of T-cell lymphoma with a leukemic phase in a raccoon dog (Nyctereutes procyonoides)

A 7.5-year-old raccoon dog (Nyctereutes procyonoides) from the Henry Doorly Zoo (Omaha, Nebraska) presented to the veterinary hospital for lethargy and weight loss. On physical examination, splenomegaly and hepatomegaly were noted on palpation and were confirmed by radiographic evaluation. Radiography also demonstrated a mass in the cranial mediastinum. A complete blood cell count revealed marked leukocytosis (115,200 cells/µl), with a predominance of lymphoid cells. The animal was euthanized due to a poor prognosis. Necropsy revealed splenomegaly, hepatomegaly, and a large multiloculated mass in the cranial mediastinum. The histologic and immunohistochemical diagnosis was multicentric T-cell lymphoma with a leukemic phase.

Epitheliotropic T-cell lymphoma in a guinea pig

A 4-year-old female guinea pig was presented with pruritic, erythematous, hypotrichotic and scaling skin lesions, mainly involving the abdomen and the hindlegs. Clinical abnormalities were limited to the skin, and the guinea pig was otherwise healthy. The dermatological diagnostic work-up excluded ectoparasites, dermatophytosis and an endocrinopathy as differential diagnoses for the pruritus and hair loss. An allergic dermatitis was under investigation when the general and skin condition deteriorated. A neoplastic skin disorder was suspected, and skin biopsies revealed changes consistent with a cutaneous epitheliotropic T-cell lymphoma. Pautrier's microabscesses and immunophenotyped CD3(+) CD79(-) lymphocytes were identified. Owing to the deteriorating condition of the animal and the unknown but most likely poor prognosis of this disease, the guinea pig was euthanized. To the authors' knowledge, this is the first case report of cutaneous epitheliotropic T-cell lymphoma in the guinea pig with characteristic histopathological and immunohistochemical features.