Thyroid Trouble in Dogs

A change in appetite can be a sign of thyroid disease.
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The thyroid gland might be small, but it can cause significant health problems if it doesn’t function properly. One obvious sign of the most common type of thyroid problem in dogs is a change in your pet’s coat. Although changes can occur for a variety of reasons, it’s a good idea to take your dog to the veterinarian if you notice coat changes or other potential signs of thyroid trouble.

Not Enough

Hypothyroidism occurs when your dog’s thyroid gland doesn’t make enough thyroid hormones. The thyroid gland is a butterfly-shaped gland at the front of your dog’s neck. A healthy thyroid gland produces hormones that control metabolism, growth and brain development, and regulate your dog’s body temperature. If your dog has hypothyroidism, you might notice that his coat is dull or has bare spots. He might have less energy, gain weight, shed more and seems more sensitive to the cold. If a blood test confirms that your dog has hypothyroidism, your vet will prescribe an oral replacement medication that your dog will take every day.

The Danger Zone

If hormone levels drop to dangerous levels, your dog might develop myxedema and could fall into a myxedema coma. Fortunately, these comas rarely occur, but it’s a good idea to learn the warning signs if your dog has hypothyroidism. If your pet develops myxedema, you might notice that his jowls and the area above his eyes look swollen. Your dog also might become very cold and weak, seem depressed, have a low heart rate and blood pressure, and might even collapse. If you observe these symptoms, it’s important to take your dog to a veterinarian immediately, as the condition can be fatal. Treatment includes gradually warming your dog and prescribing thyroid and antibiotic medications.

Too Much

Hyperthyroidism occurs when hormone production is too high. The PetMD website notes that hyperthyroidism is rare and most commonly occurs in dogs with thyroid cancer, although it can happen if your dog has hypothyroidism and his medication dosage is too high. If your dog has hyperthyroidism, he might lose weight, seem hungrier and thirstier, urinate more and experience vomiting and diarrhea. You might notice rapid breathing, a dull coat and irritability. Treatment of hyperthyroidism includes prescription of medication to lower hormone production, adjusting medication dosage or treating or removing a cancerous tumor.

When Cancer Strikes

Although your dog might show signs of hyperthyroidism if he has a cancerous tumor, many dogs show no signs other than a lump in the neck. If the lump is large or deep, you might notice that your dog’s bark has changed, he coughs frequently or has trouble swallowing. If the tumor hasn’t spread and hasn’t attached itself to surrounding body parts, your dog’s veterinarian might recommend surgical removal. Several options are available when the tumor can’t be surgically removed, including chemotherapy, radiation or radioiodine therapy -- three types of therapies that kill cancer cells. Special thyroid supplements that slow cancer cell growth also might be prescribed.