Abstract
The thyroid is an endocrine gland that secretes hormones relevant to metabolism (T3 and T4), in addition to others responsible for calcium and phosphorus metabolism. Hypothyroidism is an endocrinopathy related to decreased concentrations of T3 and T4, which causes the animal to suffer clinical and metabolic alterations, resulting from the decreased metabolic rate. Hypothyroidism can be classified as primary (the most common), secondary or tertiary. Some of these alterations may be metabolic, dermatological, cardiovascular, neurological and reproductive. To confirm the diagnosis, it is necessary to obtain a good clinical history and physical examination, accompanied by complementary tests, among which the standard hormone tests. A misdiagnosis is common due to the occurrence of nonspecific signs, which can be confused with those of other diseases; hence the importance of confirming the disease by performing hormone tests. The best and feasible diagnostic method involves the measurement of serum levels of free T4, total T4 and TSH. After the diagnosis has been confirmed, specific treatment should be performed by supplementation by levothyroxine sodic. This study aimed to conduct a review on canine hypothyroidism, considering its etiological, clinical, diagnostic and therapeutic aspects.