Mustelids

DEVELOPMENT OF A MOBILITY ASSESSMENT SCORE FOR EVALUATION OF THE EFFECTS OF ORAL HYALURONIC ACID ON CLINICAL LAMENESS IN ASIAN SMALL-CLAWED OTTERS (AONYX CINEREA) AND AFRICAN SPOT-NECKED OTTERS (HYDRICTIS MACULICOLIS) UNDER HUMAN CARE

Oral hyaluronic acid has been shown to reduce inflammation and pain in humans with osteoarthritis. Eight Asian small-clawed otters (Aonyx cinerea) and two African spot-necked otters (Hydrictis maculicolis) with varying degrees of osteoarthritic changes identified on radiographs were selected for a randomized, double-blinded, placebo-controlled clinical trial. Animal husbandry staff completed otter mobility assessment (OMA) questionnaires for each animal prior to study commencement and following either oral hyaluronic acid at a loading dose of 4 mg/kg PO SID for 10 d followed by a maintenance dose of 2 mg/kg PO SID for 20 d, or placebo for 30 d. Four veterinarians with experience assessing otters watched randomized videos of otter gaits and assigned a clinical lameness score. Two additional evaluators watched the videos: an experienced veterinarian in small animal practice and a final-year veterinary student. All evaluators for OMA and clinical lameness score were blinded to treatment group. Radiographs performed prior to, and following, the study were assessed by a board-certified radiologist (Dennison). The OMA questionnaire had high reliability coefficients and correlated strongly with clinical gait scores and radiographic assessment. Although hyaluronic acid appears to be safe for use in otters at the dose described, there was no observed significant effect of hyaluronic acid on clinical lameness scores, OMA scores, or radiographic assessment of the limbs. The development of the OMA questionnaire is a promising tool for evaluating lameness in managed-care otters and may be further validated in future studies investigating therapeutics or incorporated as a component of animal welfare assessment.

Primary intracranial fibrosarcoma in a southern sea otter Enhydra lutris nereis

Southern sea otters Enhydra lutris nereis, a threatened marine mammal species, face numerous environmental and infectious disease challenges in their native habitat of coastal California, USA. However, there are few published cases describing neoplasia in sea otters despite their relatively long life span when cared for in aquarium settings. An 18 yr old neutered male southern sea otter, born and raised in human care, presented with an acute onset of seizures and dull mentation. Magnetic resonance imaging of the head revealed a large, central brain lesion. After no improvement with treatment, euthanasia was elected due to a poor prognosis. Grossly, a poorly demarcated, granular, tan mass expanded the cranial meninges in the longitudinal fissure at the level of the cruciate sulcus and extended into the underlying gray matter and superficial white matter. Histologically, the mass was composed of spindle cells, forming haphazardly arranged interlacing bundles and herringbone patterns, with a high mitotic count, moderate cellular pleomorphism, and prominent vascularization. Neoplastic cells demonstrated positive immunoreactivity for vimentin and negative immunoreactivity for smooth muscle actin, factor VIII-related antigen, S100, melan-A, E-cadherin, desmin, glial fibrillary acidic protein, and cytokeratin AE1/AE3. Based on gross, histologic, and immunohistochemical findings, the mass was most consistent with a primary intracranial fibrosarcoma (PIF). PIFs are a rare neoplasm in both humans and other animals with few reports in the veterinary literature. This is the first recorded case of a PIF in a sea otter.