Prevalence of feline hyperthyroidism in mature cats in urban population in Warsaw

The purpose of this study was to assess the prevalence of feline hyperthyroidism in a cat population in Warsaw, considering risk factors. The study was conducted between June 2007 and July 2011. Seven-year-old and older cats were examined. Diagnosis of feline hyperthyroidism was based on the results of clinical examination, data from clinical history, and serum concentrations of thyroid hormones. Hyperthyroidism was diagnosed in 20.14% of 417 cats (95% confidence interval (CI): 16.28%-24.01%). Statistically significant risk factors were age (odds ratio (OR) = 1.17; 95% CI: 1.08-1.27), feeding with a commercial wet feed (OR = 6.74, 95% CI: 2.03-22.37), and an indoor lifestyle (OR = 2.25, 95% CI: 1.04-4.84). There were no effects of breed, gender, castration, or the frequency of deworming on the occurrence of hyperthyroidism. Feline hyperthyroidism in Warsaw is a prevalent disease. This probably results from chronic exposure to dietary and environmental factors.