Food-induced thyrotoxicosis in a dog

Abstract

This report presents a case of factitial thyrotoxicosis in a dog ensuing from the long-term administration of a raw meat-based pet food adulterated with thyroid tissue. A 7-year-old, male, neutered bull terrier was brought to the clinic because of polyuria/polydipsia, restlessness and a decrease in bodyweight despite increased appetite. Physical examination revealed hyperthermia, polypnea, tachycardia and a mild underconditioning, whereas routine bloodwork and urinalysis were unremarkable. Exogenous thyrotoxicosis was suspected based on thyroid function test results, together with contrast computed tomography and nuclear scintigraphy of the thyroid gland, showing increased serum T4 concentrations and very low thyroid-stimulating hormone concentration in the absence of either eutopic or ectopic thyroid tumours. Histological and biomedical analyses of the dog's diet identified it to be the likely source of environmental thyroid hormones. Diagnosis confirmation was achieved by transitioning the dog to a new food, which was accompanied by a speedy and full remission of clinical signs.