Clinicopathological features in 620 neurological cases of canine distemper

Abstract

The files of 5,361 necropsies performed in dogs in the Veterinary Pathology Laboratory of the Federal University of Santa Maria during 1965-2006 were reviewed in search of cases of canine distemper. Six hundred and eighty three cases (12.7%) of the disease were found, 620 of which had neurological signs. From those 620, the following data on each case were retrieved: age, clinical signs, histopathology and concomitance or not of another disease. Age groups were classified as puppies (up to 1 year of age), adults (from 1 to 9 years) and aged (from 10 years on). In 565 out of the 620 (91.1%) neurological cases of canine distemper, histopathological brain changes were observed and in 554 of those 565 the age was registered in the files with following age group distribution: 45.9% of puppies, 51.4% of adults, and 2.7% of aged dogs. Neurological clinical signs encompassed a large spectrum of motor, postural and behavioral disturbances which could occur together or individually. Most frequent clinical signs were myoclonus (38.4%), motor incoordination (25.0%), seizures (18.5%), and paraplegia (13.4%). In 98.4% of the 565 dogs with histopathological changes in the brain demyelination, nonsuppurative encephalitis or a combination of these two were found. Intranuclear eosinophilic inclusion bodies were observed in different brain cells of 343 of the 565 dogs with histopathological changes. In 170 (49.6%) the cellular type bearing the inclusions was not mentioned in the file and in the remaining cases the inclusions were seen in astrocytes (94.8% of the cases), neurons (3.5%), oligodendrocytes (1.1%), and ependyma cells (0.6%). Taking in consideration the type of lesions and the age groups, cases with combined demyelination and non-suppurative encephalitis occurred in 40.0% of the puppies, 51.2% of the adult dogs and 72.7% of the aged dogs. Demyelination alone occurred in 48.4% of the puppies, 41.3% of the adults and in 35.7% of the aged dogs. Non-suppurative encephalitis alone occurred 11.6% of the puppies, 7.5% of the adults and in 7.1% of the aged dogs.