Bovine nasal granuloma: nasal eosinophilia.

A prospective study of nasal eosinophil counts was made in Jersey and Friesian dairy cattle at Leongatha, and of Hereford, Aberdeen Angus and Shorthorn cattle at Kilmore, Victoria. Mean nasal eosinophil counts in subgroups of cattle were found to correlate with the known susceptibility of Jerseys and Friesians to develop bovine nasal granuloma, and to reflect the known seasonal activity of the disease, thus confirming the validity of nasal eosinophil counts as an index of clinical activity of nasal granuloma. Peaks in mean nasal eosinophil counts in cattle which developed lesions of bovine nasal granuloma during study correlated with periods of warm moist environmental conditions. This finding suggests microbial spores may be the allergen(s) in bovine nasal granuloma, and indicates that the allergen(s) might be identified by simultaneously monitoring the pasture particle content and assessing nasal eosinophilia in cattle with the disease. The detection of nasal eosinophilia in some cattle by 6 to 9 months of age also suggests early sensitisation to allergen(s); if the allergen(s) were identified they might be used to detect cattle prone to nasal granuloma at this early age. Early detection of predisposed animals would open the possibility of control of the disease by genetic selection.