Diseases diagnosed in calves in southern Rio Grande do Sul, Brazil

The aim of this study was to report the frequency of diseases affecting cattle under one year of age in the area of influence of the Regional Diagnostic Laboratory (LRD) of the Veterinary School of the Federal University of Pelotas (UFPel), establishing the main epidemiological factors associated with the occurrence of these diseases. The necropsy protocols and protocols of mailed in tissues from cattle under one year of age, submitted during 20002011 to LRD/UFPel for diagnosis, were reviewed. In 35.6% of the cases, the calves were of dairy breeds, 33.9% were beef calves, 18.3% were of mixed breed, and in 12.1% of the cases the breed was not informed. The organ systems most affected were the central nervous system (22.7%), digestive tract (18.6%) and respiratory system (16.8%). The diagnoses were divided by age groups: 88 calves were 1-90 days of age, 42 were 4-6 months, 32 were 7-9 months, and 44 cattle were 10-12 months of age. The disease most often diagnosed in 1 to 90-day-old calves were pneumonia, malformations and encephalitis/meningoencephalitis, with 19.3%, 15.9% and 11.3% of cases respectively. In 4 to 6-month-old calves, pneumonia occurred in 16.5% of cases, and blackleg and diarrhea accounted for 7.1% of diagnoses each. In 7 to 9-month-old calves the most frequent diseases were pneumonia and tetanus with 9.3% of cases, and babesiosis and gastrointestinal parasitosis with 6.2% each. In 10 to 12-month-old calves, infection by BoHV-5 represented 13.6% of cases, and pneumonia, rabies and parasitosis was observed in 9% of cases each. Based on the results of this study it can be concluded that infectious diseases related to the respiratory system were important causes of mortality in calves of all ages until 12 months in the area of influence of LRD and their occurrence may be influenced by environmental factors and by management. Encephalitis/meningoencephalitis were also important as cause of mortality in 3-month-old calves.