Hypothyroidism is the most common hormonal imbalance in dogs. It is a lifelong condition that significantly decreases quality of life and is associated with several other negative health outcomes including obesity, lethargy, and skin conditions. Airedale Terriers, Doberman Pinschers, Miniature Schnauzers, Pomeranians, Golden Retrievers, Cocker Spaniels, Shetland Sheepdogs, Irish Setters, Dachshunds, Tibetan Terriers, and Boxers are more affected by hypothyroidism compared to other breeds. In these high-risk breeds, dogs under a year old may also develop hypothyroidism, presenting lifelong challenges to living an active lifestyle alongside their owners.
Regardless of breed, spaying and neutering increases the likelihood of developing hypothyroidism such that 30% of dogs that are spayed or neutered develop the disease. This may be due to the overproduction of luteinizing hormone (LH; a hormone produced by the brain), which occurs after the ovaries or testicles are removed. Previous research from the investigator’s laboratory has shown that receptors for LH are in the canine thyroid gland. Hyperactivation of these LH receptors could negatively affect thyroid function, resulting in hypothyroidism.