Join Dr Jean Dodds for this informative presentation. Like humans, canines and felines commonly are affected by thyroid disorders, which are usually identified as hypothyroidism in adolescent or older dogs and hyperthyroidism in middle aged and older cats.  In dogs, hypothyroidism often stems from heritable autoimmune thyroiditis, especially in families of dog breeds and cross/hybrids known to be predisposed. This is akin to familial Hashimoto’s lymphocytic thyroiditis in people. Physicians and veterinarians should be aware that in the early inflammatory stages of thyroiditis, the patient may have no classical clinical signs of thyroid dysfunction, because it takes from 8-12 months to be manifested once at least 30% of the thyroid gland is damaged or impaired.  Importantly, accurate diagnostic screening and regular testing as people and pets age are essential for identification, and successful management and treatment.