Abstract: Melengestrol acetate (MGA) is the most widely used contraceptive in zoo felids, but the mechanism of contraception and the pathologic effects have not been investigated. For this study, the effects of MGA on folliculogenesis were assessed, and the association of MGA with ovarian lesions was evaluated. Comparisons were made among the histopathologic findings in the ovaries from 88 captive wild felids (representing 15 species) divided into three groups: 37 currently contracepted with MGA, eight previously exposed to MGA, and 43 never contracepted. Ninety-one percent of the felids evaluated had tertiary follicles, and no differences were noted between contracepted and uncontracepted cats. Some MGA-contracepted cats also had corpora lutea indicating recent ovulation. These results indicate that folliculogenesis is not suppressed by current doses of MGA and ovulation occurred in some cats. Therefore, the contraceptive actions of MGA do not occur by suppressing folliculogenesis, and MGA-contracepted felids likely have endogenous estrogens that may confound progestin effects on the uterus. Cystic rete ovarii was the most common pathologic finding, but they were not more prevalent in MGA-contracepted cats. These findings indicate that MGA is not associated with ovarian disease, including ovarian cancer, in contrast to the uterine lesions noted in MGA-treated cats.

Abstract: Degenerative spinal disorders, including intervertebral disc disease and spondylosis, seldom occur in domestic cats. In contrast, a retrospective study of 13 lions (Panthera leo), 16 tigers (Panthera tigris), 4 leopards (Panthera pardis), 1 snow leopard (Panthera uncia), and 3 jaguars (Panthera onca) from the Knoxville Zoo that died or were euthanatized from 1976 to 1996 indicated that degenerative spinal disease is an important problem in large nondomestic felids. The medical record, radiographic data, and the necropsy report of each animal were examined for evidence of intervertebral disc disease or spondylosis. Eight (three lions, four tigers, and one leopard) animals were diagnosed with degenerative spinal disease. Clinical signs included progressively decreased activity, moderate to severe rear limb muscle atrophy, chronic intermittent rear limb paresis, and ataxia. The age at onset of clinical signs was 10-19 yr (median = 18 yr). Radiographic evaluation of the spinal column was useful in assessing the severity of spinal lesions, and results were correlated with necropsy findings. Lesions were frequently multifocal, included intervertebral disc mineralization or herniation with collapsed intervertebral disc spaces, and were most common in the lumbar area but also involved cervical and thoracic vertebrae. Marked spondylosis was present in the cats with intervertebral disc disease, presumably subsequent to vertebral instability. Six of the animals' spinal cords were examined histologically, and five had acute or chronic damage to the spinal cord secondary to disc protrusion. Spinal disease should be suspected in geriatric large felids with decreased appetite or activity. Radiographic evaluation of the spinal column is the most useful method to assess the type and severity of spinal lesions.

Abstract: Two adult snow leopards (Panthera uncia), male and female, both with vaccinations current, became infected with feline panleukopenia virus (FPV) at the Blank Park Zoo, Des Moines, Iowa, in late 1988. Clinical signs included weakness, hemorrhagic feces, fever, seizures, and nasal discharge. Blood analysis revealed severe lymphopenia and mild anemia. A positive enzyme-linked immunosorbent assay (ELISA) test for FPV on fecal contents from the male leopard confirmed the diagnosis. In spite of intensive therapy, both animals died. Necropsy of the female, which survived for 1 wk after onset of signs, revealed intestinal crypt necrosis, pulmonary consolidation, necrotizing laryngitis, and diffuse lymphoid depletion. The male leopard, which lived 3 wk after onset of illness, had similar enteric and lymphoid lesions. In addition, there was a severe interstitial pneumonia, with syncytial cells containing eosinophilic intracytoplasmic inclusion bodies. Ultrastructural characteristics of these inclusions featured tubular structures consistent with a paramyxovirus. Although repeated virus isolation attempts from the affected lung were negative, polyclonal and monoclonal fluorescent antibody tests were strongly positive for canine distemper virus (CDV). Frozen paired sera from each leopard demonstrated very high acute and convalescing titers to FPV; both animals also seroconverted to CDV, with titers in the male leopard higher than those in the female. Additional tests for toxoplasmosis, feline infectious peritonitis, feline rhinotracheitis, feline calicivirus, feline leukemia, canine parainfluenza, and bovine respiratory syncytial virus were all negative. The neurologic signs present in these leopards remained unexplained, but may have been attributable to CDV infection. A feral cat trapped on zoo property had feces positive for FPV by ELISA. Although the specific contributions of FPV and CDV toward the development of this case are unknown, it is likely that initial FPV-induced immunosuppression allowed the subsequent development of CDV in these snow leopards. The likelihood that initial FPV infection came from feral cats underscores the importance of feral animal control on zoo premises.

Abstract: Spontaneous occurrence of toxocariasis (Toxocaracati) in captive snow leopards with symptoms of diarrhoea, general malaise, letherapy, dehydration, partial or complete anorexia, vomiting with or without expulsion of the ascarid is reported. Response to anthelmintic drug pyrantal pamoate along with antibacterial drug sulphadimethyl pyrimidine and supportive therapy is recorded.