Heritability of hypothyroidism in the Finnish Hovawart population

Abstract

BackgroundThe Hovawart is a working and companion dog breed of German origin. A few hundred Hovawart dogs are registered annually in Finland. The most common disease with a proposed genetic background in Hovawarts is hypothyroidism. The disease is usually caused by lymphocytic thyroiditis, an autoimmune disorder which destroys the thyroid gland. Hypothyroidism can be treated medically with hormone replacement. Its overall incidence could also be reduced through selection, provided that the trait shows an adequate genetic basis. The aim of this study was to estimate the heritability of hypothyroidism in the Finnish Hovawart population.ResultsThe pedigree data for the study were provided by the Finnish Kennel Club and the hypothyroidism data by the Finnish Hovawart Club. The data included 4953 dogs born between 1990 and 2010, of which 107 had hypothyroidism and 4846 were unaffected. Prior to the estimation of heritability, we studied the effects of gender, birth year, birth month, and inbreeding on susceptibility to hypothyroidism. Heritability was estimated with the probit model both via restricted maximum likelihood (REML) and Gibbs sampling, using litter and sire of the dog as random effects. None of the studied systematic effects or level of inbreeding had a significant effect on susceptibility to hypothyroidism. The estimated heritability of hypothyroidism varied from 0.47 (SE = 0.18) using REML to 0.62 (SD = 0.21) using Gibbs sampling.ConclusionsBased on our analysis, the heritability of hypothyroidism is moderate to high, suggesting that its prevalence could be decreased through selection. Thus, breeders should notify the breed association of any affected dogs, and their use for breeding should be avoided.

Assessment of the likelihood of hypothyroidism in dogs diagnosed with and treated for hypothyroidism at primary care practices: 102 cases (2016‐2021)

“…However, it raises the concern that a lack of knowledge regarding the fact that some factors could reduce the sensitivity and specificity of thyroid function tests. Multiple nonthyroidal factors including breed, 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 concurrent illness, 39 , 40 , 41 certain medications, 42 , 43 , 44 , 45 , 46 age, 34 and sex 4 can significantly affect the results of measured TT4, TSH and fT4 concentrations. Drugs such as glucocorticoids, phenobarbital, aspirin, ketoprofen, carprofen, clomipramide, and sulfonamides affect the results of thyroid function tests.…”

Laboratory indicators of hypothyroidism and TgAA-positivity in the Eurasian dog breed

“…However, the data of the present study cannot clarify this notion. There have been contradictory reports on whether sex and neutering status influence the likelihood of developing hypothyroidism [31,47,50,55,56,[58][59][60]. To date, a clear consensus on a sex-based predisposition is not available.…”

Hypothyroidism in canine reproduction

“…This leads to the conclusion that the underlying genetics are likely a polygenic trait that varies from one breed to another and that developing hypothyroidism is also heavily influenced by environmental factors. 6 Penetrance of the offending alleles is also likely to have a role in the expression of clinical disease. Despite these drawbacks, there are testing mechanisms that help screen potential breeding stock and assist breeders and veterinarians in choosing animals less likely to pass hypothyroidism on to their offspring.…”

“…4,5 Breeds that have a high incidence of thyroglobulin autoantibodies (TgAA) (antithyroglobulin antibodies) include Boxers, Dalmatians, Giant Schnauzers, Great Danes, Setters, and Old English Sheepdogs, among others. 1,[3][4][5][6][7] Diagnosis should be based on serologic testing and not on clinical signs alone as there are many diseases and medications, or even breed differences, that contribute to altered circulating thyroid hormone concentrations. Accurate testing should be utilized before supplementation is considered.…”