Can Feline Hyperthyroidism Cause Seizures?

Hyperthyroidism can cause neurological symptoms like tremors or seizures, but the right treatment can help.

If your cat has been diagnosed with hyperthyroidism, you might already be juggling a handful of concerns: weight loss, zoomies at 2 a.m., and an appetite that rivals a teenage boy’s. But seizures? That one might feel completely out of left field.

We get it. Seeing your cat tremble, twitch, or collapse can be downright terrifying. So if you’ve asked yourself, “Could this be related to their thyroid issue?” you’re not alone–and yes, it could be.

At the Centers for Advanced Thyroid Therapy (CATT), we’ve helped thousands of cats reclaim their health through I-131 radioiodine therapy, the gold standard for treating hyperthyroidism. And part of that journey is educating loving pet parents (like you!) on every possible symptom, seizures included.

What You’ll Learn:

• Whether feline hyperthyroidism can actually cause seizures

• What signs to watch for (even the sneaky ones)

• Why I-131 is the most effective way to treat hyperthyroidism and bring your cat relief

So grab your favorite mug of tea (or a cat in your lap), and let’s dive in.

How Hyperthyroidism Affects the Nervous System

Let’s talk science for a second. The thyroid gland is tiny, but when it’s overactive, it creates chaos. In hyperthyroid cats, metabolism goes into overdrive. Heart rate? Up. Blood pressure? Up. Brain activity? Also up, and that’s where things can get tricky.

Here’s how hyperthyroidism may lead to neurological symptoms like seizures:

• Brain on overdrive: Too much thyroid hormone can make nerve cells hyper-excitable. That’s fancy talk for "it takes less to cause a seizure."

• Hypertension havoc: High blood pressure can damage blood vessels in the brain, increasing the risk of stroke or seizure activity.

• Energy drain: A revved-up metabolism uses more oxygen and glucose. If your cat’s brain isn’t getting enough fuel, neurological issues—like tremors or seizures—can follow.

Are Seizures Common in Hyperthyroid Cats?

Short answer: not really. Seizures are rare but not impossible.

Most cats with hyperthyroidism don’t experience seizures, but in advanced or untreated cases, it’s been known to happen. One case even documented a kitty with jaw weakness and trouble eating—both of which resolved after thyroid levels were brought under control. Wild, right? (DMV360.com)

More commonly, you’ll see signs like:

• Twitching or leg tremors (especially in the face or limbs

• Confusion or pacing

• Sudden bursts of energy (followed by a crash nap that could rival your Sunday comedown)

If anything feels “off,” don’t wait—your vet is your best ally here.

How to Recognize Seizures in Hyperthyroid Cats

 If your cat experiences seizures, a veterinary exam can help determine if feline hyperthyroidism is the cause.

Seizures can look different from cat to cat. Some are subtle; others are hard to miss. Either way, they’re always serious.

Here’s what to watch for:

• Twitching or facial spasms: Think little muscle jerks or leg tremors.

• Loss of balance or coordination: Your cat may stumble, fall, or act strangely confused.

• Stiff limbs or convulsions: These can include paddling, stiffening, or even falling over suddenly.

• Vocalizing: Some cats let out loud cries or meows right before or after a seizure.

• Foaming or drooling: Not cute. But it happens.

• Temporary confusion or blindness: Your cat may stare off into space or seem not to recognize you afterward.

Seizures usually last under a minute, but the post-seizure “hangover” can be just as important to watch. If your cat seems dazed, anxious, or extra clingy, they’re probably recovering—and they need your calm presence.

What to Do If Your Cat Has a Seizure

Okay, deep breath. If your cat has a seizure, here’s what to do:

• Keep them safe: Gently move anything they could bump into—lamps, chairs, that stack of Amazon boxes.

• Hands off the mouth: Cats won’t swallow their tongues, but they might bite if you try to touch them.

• Dim the lights and quiet the room: A soothing environment helps the brain reset.

• Time it: Anything longer than two minutes needs urgent attention.

• Track symptoms: Is this a one-time thing, or are there other signs like weight loss or thirst? That context helps your vet a ton.

When to See a Vet

Weight loss is a key symptom of feline hyperthyroidism, making early diagnosis and the right treatment essential.

If your cat has been diagnosed with hyperthyroidism and starts showing neurological signs (tremors, twitching, seizures), it’s time for a deeper look. Even if it only happened once, don’t shrug it off.

Paired with symptoms like:

• Rapid weight loss

• Increased thirst or urination

• Restlessness or pacing

…it’s probably not just “one of those cat things.” These signs point to a thyroid imbalance that needs treatment—and the sooner, the better.

How I-131 Therapy Works

I-131 therapy targets only abnormal thyroid cells, restoring normal hormone levels and eliminating symptoms.

This advanced treatment is as simple as it is effective. Here’s how it helps your cat:

• A small dose of radioactive iodine (I-131) is injected under the skin, just like a routine vaccine.

• The iodine travels directly to the overactive thyroid tissue, destroying only the abnormal cells.

• Healthy thyroid tissue remains untouched, allowing your cat’s hormone levels to return to normal.

• Within a few weeks, symptoms like weight loss, hyperactivity, and potential neurological effects begin to resolve.

Why I-131 Is the Best Option for Hyperthyroid Cats

I-131 therapy eliminates feline hyperthyroidism, giving cats a healthier, happier life—and owners peace of mind.

Many cat owners are relieved to learn that I-131 therapy is a one-time treatment with a lifetime of results. Unlike other treatment methods, it offers:

• No daily medication: No more struggling with pills or worrying about side effects.

• No invasive surgery: No anesthesia, no stitches, just a quick and painless injection.

• A permanent cure: Most cats return to normal thyroid function within weeks.

• Improved quality of life: Without the stress of hyperthyroidism, your cat can live a happier, healthier life.

Give Your Cat a Lifetime of Health

At Centers for Advanced Thyroid Therapy (CATT), we specialize in I-131 radioiodine therapy, offering a stress-free, permanent solution for hyperthyroidism. Our expert team is here to help your cat feel their best again.

Contact us today to learn how I-131 therapy can cure feline hyperthyroidism with just one injection and a lifetime of results.