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Reviewed for accuracy on November 13, 2018, by Dr. Katie Grzyb, DVM
By Rebecca Desfosse
The thyroid is a small but important gland in the neck. A cat’s thyroid or dog’s thyroid consists of two segments, one on each side of the windpipe. This gland produces the hormone thyroxine, along with several other important thyroid hormones. In a healthy pet, these hormones automatically work together to coordinate your pet’s energy levels, growth, body temperature and heart rate.
Cat thyroid problems and thyroid problems in dogs occur when the hormone levels become too high or low. According to Dr. Rachel Barrack, DVM, CVA, CVCH and founder of Animal Acupuncture in New York City, signs of a thyroid problem in dogs or cats occur gradually and can be easy to miss. “Symptoms are often subtle at first but become more overt with progression of the disease,” she says.
Pet owners can sometimes fail to recognize a cat or dog thyroid issue until their pet is at risk for more serious complications. That’s why it’s important to be aware of the subtle signs and symptoms. If you know what to look for, you can bring it up to your vet and possibly catch the disease in its early stages.
Thyroid Disease in Dogs and Cats
Thyroid problems are extremely common in pets. However, dogs and cats aren’t typically affected the same the way. Dogs are most commonly afflicted with hypothyroidism, or low thyroid hormone levels. According to Lori Pasternak, DVM and co-founder of Helping Hands Affordable Veterinary Surgery and Dental Care, hypothyroidism usually affects dogs around the age of 2 to 7 years old.
Hyperthyroidism, or high thyroid hormone levels, is more common in cats. While dogs and cats can be diagnosed with hyperthyroidism at any age, cats generally don't show signs of hyperthyroidism until they are at least 7 years old. While either disease can occur in both species, it is rare.
Here are the key symptoms of cat and dog thyroid problems to look out for:
1. Changes in Behavior or Activity Level
According to Dr. Pasternak, the biggest sign of a thyroid problem is changes in your pet’s behavior or activity level. “Generally, when pets exhibit behavior changes, it is usually their way of telling us something is wrong,” she says.
Since the thyroid hormone helps regulate your pet's energy level, a common sign of hypothyroidism in dogs (low thyroid) is that they tend to be less active or lethargic. Your dog may seem less playful at the dog park, or doesn’t want to play fetch, or just won’t walk as far as he used to. He might also be sleeping more than usual or won’t get up with you in the morning.
Cat hyperthyroidism (high thyroid levels) is the opposite problem—they tend to have more energy than usual. According to Dr. Pasternak, this can sometimes be tricky to pinpoint. “Most people think it is a good thing when their older cat starts becoming more active,” she says. “They don't realize it’s a thyroid issue until the levels are so high that the cat starts to show more serious signs.” While increased energy might be a good sign in your older cat, it’s always best to run it by your vet to rule out a cat thyroid problem. Other symptoms commonly seen with hyperthyroidism in cats include increased thirst, urination, hunger and vocalization as well as intermittent vomiting.
2. Weight Gain or Loss
Another sign of thyroid problems in dogs is weight gain that’s not caused by overeating. Instead, your pet slowly packs on a few pounds despite you feeding him a normal diet. According to Dr. Barrack, this weight gain can even lead to obesity in your pet if the thyroid problem isn’t corrected.
Conversely, cats with thyroid problems often experience weight loss, despite having a ravenous appetite. As with increased energy, Dr. Pasternak cautions owners against mistaking increased appetite in an older cat for a good thing. When paired with weight loss, it’s always something you should bring up to your vet.
3. Skin or Coat Problems
Skin and coat issues are also a sign of thyroid problems in dogs. Hypothyroidism typically causes dull hair, hair loss or a dry coat, according to Dr. Pasternak. You might notice that your pet’s skin flakes off more than usual when you’re brushing him. Or, he might start to experience patches of thinning hair.
Hyperthyroidism in cats causes the opposite problem. According to Dr. Barrack, your cat’s coat may start to look greasy and matted. Cats will sometimes stop grooming themselves and develop an unkempt appearance.
4. Intolerance to Cold
According to Dr. Barrack, aversion to cold can indicate hypothyroidism in dogs. You might notice your pet shivering in the cold or turning back toward the house to cut potty breaks short on cold days. He might also sit close to the heat vent, burrow under blankets or be reluctant to leave his warm bed.
5. Vomiting or Diarrhea
Over time, hyperthyroidism in cats can progress to a more serious symptoms, such as vomiting. “Left untreated, cats with thyroid problems can also develop secondary problems such as high blood pressure and heart disease,” warns Dr. Barrack.
If your pet is experiencing any of these symptoms, talk to your veterinarian. If your dog or cat does have thyroid problems, they can typically be treated with prescription pet medication. However, when left untreated, these problems can greatly affect the quality of your pet’s life.
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