What is Endocrinology in Dogs and Cats?

Your Pets Hormonal Health

Endocrinology is the branch of veterinary medicine that focuses on the endocrine system—the network of glands that produce and regulate hormones. Hormones are vital chemical messengers that help regulate many of your pet’s essential bodily functions, including metabolism and growth. When the endocrine system malfunctions, it can lead to health issues that may require the expertise of a veterinary internal medicine specialist.

In dogs and cats, some of the most common endocrine disorders include diabetes mellitus, hypothyroidism, hyperthyroidism, Cushing’s disease, and Addison’s disease. These conditions may develop gradually over time and can affect pets of any breed, age, or gender—though some are more common in certain species or breeds.

Common Endocrine Diseases in Pets

1. Diabetes Mellitus
Most often diagnosed in middle-aged to senior pets, diabetes occurs when the body is unable to produce or effectively use insulin—a hormone that regulates blood sugar. In dogs, Type 1 diabetes is more common and usually requires lifelong insulin therapy. In cats, Type 2 diabetes is more prevalent. Early signs include increased thirst, frequent urination, weight loss despite normal or increased appetite, and lethargy.

2. Hypothyroidism (Dogs)
This condition, more common in dogs than cats, results from an underactive thyroid gland that doesn’t produce enough thyroid hormone. Symptoms may include unexplained weight gain, lethargy, fur and skin changes, and cold intolerance. Classic bloodwork changes are also common. Fortunately, hypothyroidism is easily managed with daily oral thyroid hormone supplementation.

3. Hyperthyroidism (Cats)
In contrast to dogs, cats—especially older cats—commonly develop an overactive thyroid, which causes elevated metabolism. Symptoms include weight loss, increased appetite, hyperactivity, vomiting, and high heart rate. Various treatment options are available for this condition, including medication, special diet or radioactive iodine therapy. Surgical treatment is rare.

4. Cushing’s Disease (Hyperadrenocorticism)
This condition results from the overproduction of cortisol, a stress hormone. It is most often seen in middle-aged to older dogs and can stem from a tumor on the pituitary or adrenal gland. Common signs include increased thirst and urination, panting, a pot-bellied appearance, and thinning skin or coat. Classic bloodwork changes are also common.

5. Addison’s Disease (Hypoadrenocorticism)
The opposite of Cushing’s, Addison’s disease involves too little cortisol production. Symptoms are often vague—vomiting, diarrhea, lethargy, and poor appetite. In some cases, symptoms can progress and become life-threatening if not diagnosed and treated promptly. Treatment involves lifelong hormone replacement.