As your pet ages, they have a good chance of developing a thyroid condition. Diseases that affect thyroid function are common in senior pets, as well as middle-aged pets. Fortunately, with proper medication, diet, and your primary care veterinarian’s regular monitoring, your beloved pet can live a happy, normal life. 

What does the thyroid gland do in pets?

The main function of your pet’s thyroid gland, which is located in the neck, is creating a hormone called thyroxine. This hormone is in charge of metabolism and affects how your pet converts food into energy. Dogs can become hypothyroid and suffer from decreased thyroxine output, while cats typically become hyperthyroid and produce excessive thyroxine.

What is hypothyroidism in dogs?

Hypothyroidism in dogs affects all breeds but is most often found in golden retrievers, Labrador retrievers, Doberman pinschers, Irish setters, dachshunds, boxers, and cocker spaniels. This condition generally occurs in middle-aged, medium- to large-breed dogs. Neutered males and spayed females also have a higher risk of developing hypothyroidism.

Hypothyroidism is thought to be caused by an immune system attack, a shrinking thyroid gland, or, rarely, a thyroid gland tumor. No matter the cause, the signs, and treatment are the same.

What are hypothyroidism signs in dogs?

Hypothyroidism signs in dogs can vary, but hair coat and weight changes are two of the most common. If your senior dog develops low thyroid function, you may notice: 

* Hair loss, usually on the trunk, rear legs, and tail

* Dull, thin hair coat

* Flaky, but not itchy, skin

* Black skin patches

* Weight gain

* Decreased appetite

* Muscle loss

* Lethargy

* Ear infections

* Cold intolerance

In rare cases, hypothyroidism can be linked to seizures, cardiovascular problems, and infertility. 

How is hypothyroidism in dogs diagnosed and treated? 

Fortunately, hypothyroidism in dogs is relatively straightforward to diagnose and treat. Your family veterinarian will run a blood thyroid panel to determine the amount of thyroxine being produced. More complicated cases may require a comprehensive thyroid testing panel that often is sent to an outside laboratory. 

Once a diagnosis has been reached, your dog will be treated with a man-made hormone known as levothyroxine or L-thyroxine. Hypothyroidism treatment will be lifelong but is fairly inexpensive and easy to treat with once- or twice-daily oral medication.

What is hyperthyroidism in cats?

Cats tend to overproduce thyroxine and develop hyperthyroidism. This condition mostly affects middle-aged or older cats and can be seen in any breed. In most cases, the enlarged thyroid gland and subsequent increased thyroxine production are caused by a non-cancerous tumor called an adenoma. However, in some cases, a malignant tumor, known as a thyroid adenocarcinoma, can be the cause.

What are hyperthyroidism signs in cats?

Cats usually develop subtle signs that become more severe as the disease progresses, including:

* Weight loss

* Increased appetite

* Increased thirst and urination

* Vomiting

* Diarrhea

* Hyperactivity

* Unkempt, matted, or greasy hair coat

Hyperthyroidism signs in cats are also commonly seen in several disorders that affect older cats, such as diabetes and kidney disease, so an accurate diagnosis is essential for proper treatment.

How is hyperthyroidism in cats diagnosed and treated?

If your family veterinarian suspects your cat has developed hyperthyroidism, based on clinical signs, they’ll perform a thorough physical exam and diagnostic testing. They’ll feel for an enlarged thyroid gland in your cat’s neck and check their heart rate. They may also check your cat’s blood pressure since hyperthyroidism often causes heart disease and hypertension. Blood work testing will include a thyroid panel to verify the thyroxine hormone level in your cat’s bloodstream. They likely will also run other blood chemistry panels, as kidney problems can develop alongside hyperthyroidism.

Four methods can be used to treat hyperthyroidism in cats: 

Medication — Most hyperthyroid medications require twice-daily dosing, which can be difficult for oral administration in cats, but a transdermal gel is effective for reducing thyroxine levels in most cases.

Radioactive iodine therapy — This treatment of choice involves injecting iodine into the cat’s bloodstream, where the radiation destroys the abnormal thyroid tissues. 

Surgery — The thyroid glands can be surgically removed with a good success rate, but complications can occur, so surgery is rarely the treatment of choice.

Dietary therapy — Iodine-restricted diets may benefit cats with hyperthyroidism, especially if other treatment options are not feasible. 

Thyroid conditions are common in senior pets, but highly effective methods are available to manage your pet’s condition, granting them a good quality of life. 

As your pet’s endocrine condition progresses, our veterinary hospice care team will guide you and your pet through their final moments, providing comfort and peace throughout the process.