6 Signs You Need To Get Your Pet’s Thyroid Checked

Perhaps you’re noticing that your previously fit dog is putting on a little weight or that your cat seems a little frazzled as of late.

What you might not know is that these are signs you need to get your pet’s thyroid checked.

In this article, you'll learn about the importance of your pet’s thyroid, the common thyroid issues that affect dogs and cats, and signs that your pet’s thyroid may not be functioning normally.

What Is the Thyroid, and What Does It Do?

The thyroid is a gland in your pet’s neck that secretes hormones that help regulate your pet’s metabolic rate or the speed at which their body converts food into energy.

The gland rests on the trachea (windpipe), with a lobe on each side. It is in turn controlled by the pituitary gland, located at the base of the brain.

If the thyroid gland doesn’t produce enough hormones—a condition known as hypothyroidism—the metabolic rate will be slowed.

If it produces too many hormones—hyperthyroidism—the metabolic rate is ramped up.

Your pet’s thyroid is an important gland for their overall well-being. Issues with the thyroid gland can significantly affect your pet’s quality of life.

Thyroid Issues in Dogs and Cats

While both dogs and cats can have hypothyroidism or hyperthyroidism, hypothyroidism is much more common in dogs while hyperthyroidism is much more common in cats.

Your veterinarian can diagnose hypothyroidism or hyperthyroidism with blood work.

Here are a few things to understand about hypothyroidism in pets:

• Hypothyroidism is most common in middle-aged dogs.

• The condition usually occurs because of the dog’s own immune system destroying parts of the thyroid gland.

• Hypothyroidism is treatable but not curable. It is usually treated with the oral medication levothyroxine, which is a synthetic thyroid hormone.

Here are some things to keep in mind about hyperthyroidism in pets:

• Hyperthyroidism most commonly occurs in middle-aged to older cats.

• Most hyperthyroidism cases in cats develop because of a benign (non-cancerous) growth on the thyroid lobes, but occasionally cases are caused by thyroid carcinoma (thyroid cancer).

• Treatment can include daily medications like methimazole (either oral or transdermal), a prescription diet like Hill’s® Prescription Diet y/d, surgical removal of the thyroid, or radioactive iodine therapy.

Signs You Need to Get Your Pet’s Thyroid Checked

Because it’s usually dogs who get hypothyroidism and cats who get hyperthyroidism, you’ll typically notice opposite signs in dogs and cats, though there may be some overlap.

Most of the signs for each condition will occur together, so you’ll especially want to get your pet’s thyroid checked if your pet is exhibiting multiple symptoms.

1. Weight Changes

Because the metabolic rate decreases in dogs with hypothyroidism, affected animals will often gain weight despite having a normal or reduced appetite. A hypothyroid dog is typically overweight or obese.

With hyperthyroidism, the opposite is true. Hyperthyroidism causes an increased metabolic rate, so your pet will often lose weight despite a normal or increased appetite.

Hyperthyroid cats are usually thinner, and you might notice a narrowing in their facial structure.

2. Vomiting, Diarrhea, or Constipation

Thyroid disease affects a pet’s bowel movements. A pet with hypothyroidism tends to have constipation, while a pet with hyperthyroidism tends to have vomiting and diarrhea.

Although a hypothyroid dog is more likely to be constipated, some may instead have diarrhea.

Signs of constipation include less frequent bowel movements, straining to defecate, and hard, dry feces. With severe constipation, vomiting may occur.

Pet parents sometimes notice that their hyperthyroid cat’s stools are softer than they used to be but wouldn’t call it diarrhea.

This is still a sign that your cat needs their thyroid level checked.

3. Behavioral Changes

Hypothyroidism can cause lethargy, dullness, and exercise intolerance. Some dogs may have increased aggressive behavior.

Keeping in mind that a pet with hyperthyroidism has an increased metabolic rate, and you can expect increased activity and restlessness. Cats with hyperthyroidism are sometimes more aggressive than usual and vocalize a lot.

4. Change in Appetite

Because the metabolic rate has changed, a change in appetite is common for thyroid issues, though some pets with thyroid disease maintain a normal appetite.

If you have a dog with hypothyroidism, you may notice that your pet is eating less, even as they’re gaining weight. The opposite is true of cats with hyperthyroidism. They often have a more ravenous appetite but continue to lose weight.

5. Intolerance to Heat or Cold

The thyroid gland also has an important role in temperature regulation. Hypothyroid pets often have an intolerance to cold, while pets with hyperthyroidism may avoid heat.

For example, your hypothyroid dog may become restless if your home is chillier at night, and your hyperthyroid cat may avoid a warming bed that they previously loved.

6. Changes to Your Pet’s Coat and Skin

A cat with hyperthyroidism often has an unkempt appearance, like they’re failing to groom themselves well.

On the other hand, a dog with hypothyroidism often loses hair on their sides, develops thickened or darker skin, and loses hair on their tail (“rat tail”). Dogs with hypothyroidism are also prone to skin infections.

As mentioned, hypothyroidism is more common in dogs, while hyperthyroidism is more common in cats.

For information about the rare cases of hyperthyroidism in dogs or hypothyroidism in cats, you can view these veterinarian-written articles.

If you’re noticing any signs of thyroid issues, make sure to contact your veterinarian. Luckily, most thyroid issues in dogs and cats have safe and effective treatments.

While hypothyroidism doesn’t currently have a cure, hyperthyroidism in cats can be cured with radioactive iodine therapies or with surgery. There are also medical and dietary methods for managing hyperthyroidism in cats.