A14-year-old 3.5-kg (7.7-lb) castrated male domestic shorthair cat was evaluated by the Neurology Service at the University of Florida Veterinary Medical Center because of a 2-month history of profound weakness, ataxia, head tremors, and suspected seizures. Approximately 1 year previously, a diagnosis of inflammatory bowel disease had been made at another veterinary hospital, which was controlled via administration of prednisolone (1.4 mg/kg [0.64 mg/lb], PO, q 12 h). One week before referral to the Veterinary Medical Center, a CBC revealed normochromic, normocytic, nonregenerative anemia (Hct, 27.9%; reference range, 30% to 48%) and a stress leukogram (WBC count, 29.2 × 103 cells/μL [reference range, 6.0 × 103 cells/μL to 10.0 × 103 cells/μL]; neutrophils, 26.1 × 103 cells/μL [reference range, 2.5 × 103 cells/μL to 12.5 × 103 cells/μL]; lymphocytes, 1.2 × 103 cells/μL [reference range, 1.5 × 103 cells/μL to 7.0 × 103 cells/μL]; monocytes, 1.9 × 103 cells/μL [reference range, 0 × 103 cells/μL to 0.8 × 103 cells/μL]; and eosinophils, 0.0 × 103 cells/μL [reference range, 0 × 103 cells/μL to 1.5 × 103 cells/μL]). Abnormalities detected via serum biochemical analyses included high hepatic enzyme activities (aspartate aminotransferase, 499 U/L [reference range, 0 to 60 U/L]; alanine aminotransferase, 564 U/L [reference range, 0 to 90 U/L]; and alkaline phosphatase, 525 U/L [reference range, 0 to 45 U/L]); high creatine kinase activity (2,701 U/L; reference range, 0 to 300 U/L); high total bilirubin concentration (0.6 mg/dL; reference range, 0 to 0.2 mg/dL); high cholesterol concentration (259 mg/dL; reference range, 95 to 175 mg/dL); and low phosphorus concentration (3.3 mg/dL; reference range, 4.0 to 6.6 mg/dL). Serum total thyroxine concentration was within reference limits (13.5 nmol/L; reference range, 12.3 to 35.7 nmol/L). At that prereferral evaluation, thoracic radiography, computed tomography of the head, and CSF analysis revealed no abnormalities; abdominal ultrasonography revealed a large hypoechoic liver, which was consistent with suspected hepatic lipidosis.
At the initial evaluation at the Veterinary Medical Center, results of a neurologic examination suggested that the cat was affected by both peripheral neuromuscular disease and CNS disease. The cat was anesthetized for magnetic resonance imaging, electrodiagnostic evaluation, and biopsy of the gastrocnemius muscle. After premedication with buprenorphine (0.025 mg/kg [0.011 mg/lb], IM), anesthesia was induced with propofol (7.0 mg/kg [3.2 mg/lb], IV) and maintained with inhaled sevoflurane at 0.5% to 1.5% in 100% oxygen. Magnetic resonance imaging did not reveal any intracranial abnormalities, but electromyographic findings were indicative of denervation; histologic examination of the gastrocnemius muscle biopsy specimen revealed evidence of a myopathy. During anesthesia, the cat developed profound hypothermia (minimum recorded rectal temperature, 32.8°C [91.0°F]) and became bradycardic; T-wave changes were evident on a lead II ECG trace. A consultation with a cardiologist was sought while the cat was still anesthetized. A grade 2/6 left parasternal systolic heart murmur was ausculted. Echocardiography revealed mild concentric hypertrophy of the left ventricle and mild mitral regurgitation, but the left atrium was apparently normal in size. Because serum thyroxine concentration (assessed 1 week earlier) and blood pressure (assessed during this initial evaluation) were within reference limits, these findings were considered consistent with mild hypertrophic cardiomyopathy.
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