Hyperthyroidism Could be the Cause of Your Cat’s Behavioral Changes

Hyperthyroidism Could be the Cause of Your Cat’s Behavioral Changes

A once-friendly feline can turn feisty overnight. Howling, attacking other pets and hissing at family members can leave owners wondering, “What’s gotten into my cat?” There’s certainly a problem here, but it’s not their attitude! What many pet parents don’t realize is that changes in their cat’s behavior could signal health issues, particularly the onset of hyperthyroidism.

Let’s take a closer look at what this disease is and how to tell if your furry friend has it.

What is hyperthyroidism?

Hyperthyroidism occurs when your cat’s thyroid glands produce too much thyroid hormone. Cats have two thyroid glands located in the neck, and the hormones they produce regulate numerous bodily functions like the metabolism and heart. A benign tumor on these glands can alter your cat’s ability to produce the appropriate hormone levels.

Thyroid hormone doesn’t merely affect the metabolism, though. Hyperthyroidism can lead to other chronic problems like difficulty processing nutrients, high blood pressure and heart disease. Excessive levels in your cat’s body can pose a serious threat and shorten their life expectancy. Prompt diagnosis and treatment is necessary because hyperthyroidism primarily affects senior cats who are less resilient when it comes to battling this disease.

Why hyperthyroidism causes behavioral changes

Hyperthyroidism comes with a host of symptoms, namely changes in your cat’s behavior. Cats with hyperthyroidism get really thirsty, which inevitably leads to excessive urination. Hyperthyroidism may also cause recurring bouts of diarrhea that your kitty can’t control. Excessive urination and uncontrollable bowel movements might mean your cat goes to the bathroom in places other than the litter box.

Some pet parents are plagued by howling in the middle of the night. There’s no need to get spooked—it’s just your cat! Excessive vocalization can be a real nuisance for cat owners trying to catch some sleep. However, this frustrating behavior could actually be a cry for help. Hyperthyroidism often causes kitties to act out when they’re most awake, which tends to be at night.

Another key behavior associated with hyperthyroidism is aggression. Some cats are born temperamental, and that’s perfectly normal. However, sudden changes in behavior are not. Cats with hyperthyroidism might begin to scratch, bite or hiss at their owners more than usual. Fellow household pets might fall victim to attacks from what used to be a friendly kitty. Hyperthyroidism makes cats restless, and they need an outlet for all that extra energy.


Behavioral changes aren’t the only symptoms of hyperthyroidism. Cat owners should also be on the lookout for weight loss, even though kitties with the disease are constantly chowing down on kibble. Your cat might stop grooming themselves, which can lead to matted and greasy fur. Other symptoms that accompany hyperthyroidism include vomiting, weakness and difficulty breathing.

It’s important for pet parents to remain patient and understand that behavioral changes are rarely an act of defiance. Rather, sudden aggression and restlessness indicate that something’s not right. Contact your vet right away if your feline friend displays any or all of these symptoms. They’ll come up with a proper diagnosis and bring your cat back to their normal friendly self.

Treatments for your kitty

The good news is that hyperthyroidism is easy to treat and often has a good prognosis. Treatment has consistently reversed the effects of hyperthyroidism in senior cats, allowing them to live a longer and more enjoyable life. Keep in mind that treatment plans aren’t one-size-fits-all. Your vet will recommend the appropriate course of action depending on your cat’s overall health condition.

Vets often prescribe medicine that limits thyroid hormone production. Pet parents can administer this at home either orally or by applying a topical gel to the skin. Owners may have to give this medication daily for the remainder of the cat’s life. Some cats also develop side effects, leading the vet to recommend an alternative form of treatment.

In terms of natural treatments, diet may play a role in helping your cat manage their symptoms if their case is mild. Natural supplements can also support normal thyroid function instead of or in tandem with other treatments.

Next time your cat lashes out, ask yourself if aggression is their normal temperament or if a deeper issue might be at play. Pet parents know their furry felines better than anyone else, so any behavior that seems out of character warrants a trip to the vet. Hyperthyroidism can get serious if it’s left untreated. When you report symptoms to your vet right away, even elderly cats can bounce back and add years on to their life.