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Thyroid hormone (levothyroxine)

Pet medication safety reference — educational information only.
Medication reference

What to know

Thyroid hormone (levothyroxine) — medication safety for dogs and cats

Call your vetReference for: dogs and cats.

Overview

Pets can be prescribed levothyroxine, but human tablet strengths often exceed typical veterinary doses per pet weight. Dogs may chew full bottles. Signs relate to excessive thyroid stimulation.

Symptoms

Panting, restlessness, fast heart rate, pacing, vomiting, diarrhea

Typical onset

3–24 hours

Formulations

Small chewable veterinary tablets can look like treats — store separately.

What to do

Call your veterinarian after ingestion — especially if many tablets missing.

This page is educational and does not replace veterinary advice. For possible poisoning or ingestion, contact UVEC at (801) 218-2227 or ASPCA Poison Control at (888) 426-4435.

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Medication safety reference

Search common household medications and why they can be risky for pets. This is not dosing guidance — when in doubt, call us or poison control.

Educational reference only. It does not replace an exam or phone advice for your specific pet. Never give human medications to animals unless your veterinarian tells you exactly what to use.

23 results · 13 emergency-level

Pets can be prescribed levothyroxine, but human tablet strengths often exceed typical veterinary doses per pet weight. Dogs may chew full bottles. Signs relate to excessive thyroid stimulation.

Symptoms
Panting, restlessness, fast heart rate, pacing, vomiting, diarrhea
Onset
3–24 hours
Formulations
Small chewable veterinary tablets can look like treats — store separately.
Recommended next step
Call your veterinarian after ingestion — especially if many tablets missing.
This tool is informational only and does not replace veterinary advice. For possible poisoning or ingestion, contact UVEC at (801) 218-2227 or ASPCA Poison Control at (888) 426-4435. Bring medication packaging when possible.
Common questions

About this tool

  • Is this tool telling me what dose to give my pet?

    No. It is a general education library about common household medications and why they can be dangerous to pets. Dosing depends on species, weight, health conditions, and the exact product — only your veterinarian should choose a medication plan for your animal.

  • My pet just ate pills. Should I use this page first?

    If you believe your pet swallowed medication, call Utah Veterinary Emergency Center or a poison hotline right away. Bring the bottle with strength (mg), formulation (tablet/capsule/liquid), and approximate number eaten.

  • Why do you ask for dog vs cat?

    Cats and dogs differ in sensitivity to many drugs (for example, acetaminophen). Filtering helps you read entries that apply to the pet you are worried about.

  • Are “natural” supplements or topical creams safer than pills?

    Not necessarily. Creams can be licked, and supplements can be concentrated or combined with other ingredients (including xylitol in some liquids). Always check labels and ask your veterinarian before exposing your pet.

  • Is this the same as calling poison control?

    No. Poison control can do case-specific triage using your pet’s weight and exact product. This page cannot replace that individualized guidance.

  • What are Utah Veterinary Emergency Center’s hours?

    We are open daily from 9:00 am to 9:00 pm for urgent care and appointments. For life-threatening emergencies outside those hours, call our number for guidance and referral to a 24-hour facility if needed.