Canine behaviors associated with hypothyroidism.

Abstract

Hypothyroidism is a relatively common canine endocrinopathy with clinical signs involving several different body systems. Many of these signs have a behavioral manifestation, including lethargy, cold intolerance, decreased libido, exercise intolerance, and weight gain. Recently, there have been anecdotal reports noting a potential relationship between hypothyroidism and canine aggression. In these circumstances, aggression may be the only presenting complaint with the animal often described as having developed a "grumpy" attitude. While the underlying basis of this association has not been determined, hypothyroidism-associated aggression should be considered a specific type of aggression that appears to respond well to thyroid hormone replacement therapy. In this Pearl of Veterinary Practice. Drs. Beaver and Haug use a case report to provide a clinical example of this unique manifestation of canine hypothyroidism. They go on to recommend that thyroid gland function be assessed in all dogs presenting with aggression problems, especially those developing slowly in mature animals. Additionally, canine hypothyroidism should be a considered differential diagnosis in dogs presenting for suspect canine cognitive dysfunction, as many of the behavioral symptoms (principally mental dullness and lethargy) are shared. A brief review of diagnosing canine hypothyroidism is also provided, including current test indications and limitations.