Lack of Association between Repeated Vaccination and Thyroiditis in Laboratory Beagles

Abstract

Background: Intensive vaccination protocols have been suggested as partially responsible for an increased prevalence of autoimmune diseases in dogs in recent years. The aim of this study was to determine whether repeated routine vaccination in dogs is associated with an increased prevalence of thyroiditis.Methodology/principal findings: We conducted a prospective experimental study with 20 healthy purpose-bred Beagles. Five dogs were vaccinated with a multivalent vaccine and a rabies vaccine. Five dogs received only the multivalent vaccine, and 5 dogs received only the rabies vaccine. Five dogs were unvaccinated controls. The multivalent vaccine was administered at 8, 10, 12, 16, 20, 26, and 52 weeks of age and every 6 months thereafter. The rabies vaccine was administered at 16 and 52 weeks of age and then once a year. Blood samples were collected 1 week before euthanasia for evaluation of thyroid profiles and measurement of antibodies directed against canine thyroglobulin. Dogs were euthanized at 5.5 years of age, and the thyroid glands were evaluated histopathologically.Thyroiditis was present in 8 of 20 (40%) dogs at postmortem examination. No association was found between a dog being vaccinated and the prevalence of thyroiditis at postmortem examination. However, the power of the study to detect such an association was low because of the unexpected high prevalence of thyroiditis in the unvaccinated control dogs. Thyroid function tests were abnormal in 2 of 8 dogs with thyroiditis but were normal in all dogs without thyroiditis.Conclusions/significance: There was no evidence to support an association between routine vaccination and thyroiditis at postmortem examination in beagle dogs after repeated vaccination.

Breed-specific reference intervals for assessing thyroid function in seven dog breeds

“…For instance, recent rabies vaccination (within 2 weeks of thyroid testing) can result in the temporary (and inconsequential) presence of TgAA in the serum of healthy dogs. 27,28 In the current study, animals that were vaccinated within 3 months of enrollment were not more likely to be TgAA positive (P = 0.15) than animals that were vaccinated >3 months prior to participation. In another study, only 20% of 171 TgAA-positive dogs developed signs of hypothyroidism within a 1-year period.…”

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

“…Thyroglobulin autoantibodies (TgAA) can be borderline positive in the months after vaccination [68]. However, this was not demonstrated in all studies [67] and no association between vaccinations and thyroiditis at postmortem examination was found [69]. To minimize any effects of vaccination, breeders of this study were advised to schedule blood sampling as late as possible after vaccination.…”

Usefulness of measuring the concentration of thyroglobulin antibodies in serum of dogs for the assessment of thyroid functioning

“…The authors observed T3 and T4 antibodies in 6.3% of the tested dogs. The frequency of occurrence of TgAb s in hypothyroidism showed by Nachreiner et al (17) (24,25) in the test performed in the group of healthy beagles verified if the routine vaccinations of dogs against contagious diseases can influence the TgAb s concentration. They proved that the last vaccination of puppies against rabies may cause an increase in TgAb s level.…”