The label says, word for word:
For replacement therapy for diminished thyroid function in dogs.
Do not use in dogs with thyrotoxicosis or uncorrected adrenal insufficiency.
Not for use in humans. Keep out of reach of children. In the event of accidental ingestion, seek medical advice immediately and show the product label to the physician. Wash hands after handling.
Keep Thyro-Tabs Canine in a secure location out of reach of dogs, cats, and other animals to prevent accidental ingestion or overdose.
In humans and rodents, excess in utero exposure to thyroid hormones is associated with hypothalamic-pituitary-thyroid axis dysfunction and morphological thyroid gland defects in the offspring. The safety of Thyro-Tabs Canine has not been evaluated in breeding, pregnant, or lactating dogs.
Every approved medicine has a field study behind it, and the label prints what happened:
In a 6-month US field study with 92 dogs, the most commonly reported adverse reactions by percentage of dogs experiencing the reaction included: anorexia (17%), dermatitis (15%), vomiting (15%), otitis externa (14%), lethargy (14%), polydipsia (13%), diarrhea (11%), leukocytosis (9%), pruritus (8%), tachypnea (8%), polyuria (5%), hyperactivity (4%), and seborrhea (1%).
Approved by FDA under NADA # 141-448; original approval January 25, 2016 (FOI summary; sponsor Lloyd, Inc.). The same product is also distributed by Butler Animal Health Supply and MWI/VetOne under the same NADA. The label's Precautions say dogs with underlying cardiac disease that are diagnosed with hypothyroidism should be closely monitored (that sentence is omitted here because it discusses dose adjustment).
The emergency page sorts the signs by how long you have, and the symptom checker asks what you are seeing. Reactions to a medicine can also be reported to the FDA yourself: how to report a problem.
These answers come from the approved label on DailyMed, read on 2 October 2026. Where the label does not say, the answer says so, and the vet or the pharmacist is the one to ask.
The approved use is quoted at the top of this page. It replaces thyroid hormone in dogs whose thyroid gland makes too little.
The label says the level of thyroid hormone in the blood peaks within 4 to 6 hours of a tablet given on an empty stomach. It gives no number of days or weeks for when the dog itself looks better. In its six-month field study, signs such as weight gain, low energy, hair loss and scaly skin had generally improved by the end of the study. The vet checks the blood level every 4 to 8 weeks until the right amount is found.
It is a tablet given by mouth, either once every 24 hours or divided into two doses 12 hours apart, and the vet chooses which. The label asks owners to give it the same way every time, either always with food or always without, because food lowers how much of the drug is absorbed and the aim is a steady level from day to day. The vet adjusts the amount from a blood sample taken 4 to 6 hours after a tablet. If your dog is switched from another levothyroxine product, the label says the blood level and the dog's response should be checked again.
The label does not say what to do about a missed dose. Call the clinic or the pharmacy before you give the next one.
The studies and the warnings are quoted above. The label has no line telling owners when to call the vet. The reactions recorded most often in its field study were eating less, skin inflammation, vomiting, ear inflammation, low energy, drinking more and diarrhea, and the list also has fast breathing and overactivity. If you see any of these, call the vet. The label says dogs with heart disease should be watched closely while the amount is being settled. If a person swallows a tablet by accident, the label says to get medical advice immediately and to show the product label to the doctor.
Store it at room temperature, between 68° and 77°F; the label allows short spells between 59° and 86°F. Protect it from light and moisture. The label says to keep it in a safe place out of reach of dogs, cats and other animals, to prevent accidental swallowing or an overdose, and out of the reach of children. It also says to wash your hands after handling the tablets.
The FDA says the best way to get rid of most unused or expired medicines is a take-back option: a drug take-back location, which can be at a pharmacy or a police station, or a prepaid mail-back envelope. If you cannot use one and the medicine is not on the FDA's flush list, the FDA says to mix it, uncrushed, with something unappealing such as dirt, cat litter or used coffee grounds and to seal the mixture in a plastic bag before throwing it away. Flushing is only for medicines on that list, such as opioids. Do not give leftovers to another pet.
Write the dose, the times and the stop date here, then print this page for the fridge.
Dose and times: _____________________________________________
Stop date: _____________________________________________