Is Thyroid Medications toxic to cats?

Moderate severity

Yes. It can cause real illness — contact your vet if your pet has been exposed.

Symptoms to watch for

muscle tremors
nervousness
panting
rapid heart rate
aggression

How vets treat it

Contact a veterinary professional or poison control helpline to determine if the ingested amount is toxic; monitoring and supportive care may be required for large ingestions.

Why it's dangerous

Large acute overdoses of thyroid hormones can overstimulate the metabolic system, leading to hypermetabolic states affecting the heart and nervous system.

Toxic compound: Levothyroxine

Good to know

Dogs have a higher tolerance for thyroid hormones than humans, and small accidental ingestions rarely cause problems due to a wide margin of safety.

Sources

Pet Poison Helpline

This page is informational and is not veterinary advice. If your pet has been exposed to something risky, contact your vet or an animal poison control line right away.

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