Feline hyperthyroidism reported in primary‐care veterinary practices in England: prevalence, associated factors and spatial distribution

Abstract

Feline hyperthyroidism is a commonly diagnosed endocrinopathy that can have a substantial deleterious impact on the welfare of affected cats. This study aimed to estimate the prevalence, associated factors and geographical distribution for feline hyperthyroidism in England, using primary-care veterinary practice clinical data from the VetCompass Animal Surveillance Project. Prevalence was estimated from the overall cat cohort. Associated factor analysis used an age-matched, nested, case-control design with multivariable logistic regression. There were 2,276 cases of feline hyperthyroidism identified from 95,629 cats attending 84 practices from September 2009 to December 2011. Cases were aged 6-25 years. 3.7 per cent of cases and 9.9 per cent of controls were purebred, 56.4 per cent of cases and 56.5 per cent of controls were female, and 88.1 per cent of cases and 86.0 per cent of controls were neutered. The apparent prevalence was 2.4 per cent (95% CI 2.3 to 2.5 per cent) overall, and 8.7 per cent (95% CI 8.3 to 9.0 per cent) in cats aged 10 years or above. Burmese (OR 0.15, 95% CI 0.07 to 0.32, P<0.0001), Persian (OR 0.17, 95% CI 0.08 to 0.33, P<0.0001), Siamese (OR 0.4, 95% CI 0.21 to 0.75, P=0.004) and purebred cats overall (OR 0.33, 95% CI 0.25 to 0.42, P< 0.0001) had lower odds of feline hyperthyroidism than non-purebred cats. Insured cats had increased odds (OR 1.78, 95% CI 1.56 to 2.03, P< 0.001). There was little evidence of spatial variation. This study highlights feline hyperthyroidism as a high-prevalence disease in England, and reports reduced odds of diagnosis in certain breeds and purebred cats overall.

Breed, Coat Color, and Hair Length as Risk Factors for Hyperthyroidism in Cats

“…Consistent with results from a previous study, our results showed the Burmese breed to be most strongly protected against development of hyperthyroidism . The colorpoint coats of Burmese and Siamese cats occur as a result of 2 separate mutations in the tyrosinase gene, with Burmese cats typically having greater ability to produce pigment in skin covering central body regions than the Siamese .…”

Feline hyperthyroidism: a common disorder with unknown pathogenesis

“…But why do these mutations occur? In agreement with previous observations (Kass and others 1999, Wakeling and others 2009), the study by Stephens and others (2014) indicates that Burmese, Siamese, Persian and purebred cats overall had lower odds of hyperthyroidism than non-purebred cats. These observations suggest that the occurrence of the mutations in the TSH receptor or the associated G proteins may be influenced by breed-specific genes.…”

“…The study by Stephens and others (2014) also shows that the risk of feline hyperthyroidism increases with age. This may reflect chronic exposure to goitrogens, which increases the risk of genetic mutations in the thyrocytes.…”

Generating Evidence Through Practice-based Equine Health Surveillance

“…These have been analysed to quantify the most common disorders affecting dogs and cats 7,8 and to establish risk factors for several important conditions 9,10 . Excitingly, VetCompass has now been adapted for use in equine practice, providing enormous opportunity for the study of equine health and the generation of robust disease statistics.…”