Epidemiological study of enzootic pneumonia in dairy calves in Saskatchewan.
In a field study involving 325 calves from 17 dairy herds in Saskatchewan the risk of pneumonia, based on producers' assessment was 39%, while that based on veterinarians' assessment was 29%. The mortality risk from pneumonia was 1.8%, and a variety of infectious organisms were isolated from pneumonic lungs. Positive titres within the first 2 weeks of life were found to parainfluenza virus 3 in 94% of the calves, bovine respiratory syncytial virus in 94%, Pasteurella haemolytica in 73%, bovine diarrhoea virus in 68%, infectious bovine rhinotracheitis virus in 67%, Mycoplasma dispar in 46%, Haemophilus somnus in 44%, and Mycoplasma bovis in 21%. Associations of positive titres with various parameters at the calf and herd level of analysis were recorded. Pneumonia clustered strongly within herds, and it was concluded that many more farms needed to be studied to understand the risk factors.