In vivo evaluation of α2-adrenoceptors in cats with idiopathic cystitis

Objective —To evaluate the in vivo response of α 2 -adrenoceptors to medetomidine administration in cats with feline idiopathic cystitis (FIC) during periods of stress and after environmental enrichment. Animals —13 cats with FIC and 12 healthy cats. Procedures —Cats were subjected to an acute-onset moderate stressor for 8 days. After stress, 20 μg of medetomidine/kg was administered IM on days 1, 3, and 8. Heart rate, blood pressure, pupil diameter, respiratory rate, and level of sedation were evaluated before and after administration of the drug. After day 8, cats were moved to an enriched environment, and tests were repeated on day 35. Results —Heart rate decreased and pupil diameter increased significantly after medetomidine administration in healthy cats, compared with cats with FIC. Cats with FIC had significantly lower respiratory rates. No significant differences in blood pressure or sedation level were found. Conclusions and Clinical Relevance —Increased plasma catecholamine concentrations during the enrichment phase, which have been reported elsewhere, may have contributed to the differences in α 2 -adrenoceptor responses detected in cats with FIC.