Animal & Veterinary

THYRO-TABS CANINE (levothyroxine sodium tablets) - Veterinarians

January 29, 2016

Dear Veterinarian:

The U.S. Food and Drug Administration (FDA) wants to tell you about the recent approval of THYRO-TABS CANINE (levothyroxine sodium tablets, New Animal Drug Application 141-448) for replacement therapy for diminished thyroid function in dogs. The product is the first, and so far only, animal drug approved to treat canine hypothyroidism. FDA also wants to remind you of the benefits of using FDA-approved drugs in your clinic.

Manufactured by Lloyd, Inc., THYRO-TABS CANINE is a prescription drug and comes in nine strengths, ranging from 0.1 mg to 1.0 mg. Please refer to the Freedom of Information Summary and package insert for THYRO-TABS CANINE before using the drug.

Benefits of FDA Approval

FDA rigorously evaluates an animal drug before approving it. As part of the approval process, the drug company must prove to FDA that:

  • The drug is safe and effective for a specific use in a specific animal species;
  • The manufacturing process is adequate to preserve the drug’s identity, strength, quality, and purity; and
  • The drug’s labeling is truthful and not misleading.

FDA’s role does not stop after the agency approves an animal drug. As long as the drug company markets the animal drug, the agency continues to monitor:

  • The drug’s safety and effectiveness. Sometimes, the agency’s post-approval monitoring uncovers safety and effectiveness issues that were unknown at the time of approval;
  • The manufacturing process to ensure quality and consistency are maintained;
  • The drug’s labeling to make sure the information remains truthful and not misleading; and
  • The company’s marketing communications related to the drug to make sure the information is truthful and not misleading.

Other Marketed Levothyroxine Sodium Products

A number of other levothyroxine sodium products are currently marketed in the U.S. for use in dogs; however, none are FDA-approved. In January 2016, FDA issued warning letters to companies manufacturing an unapproved levothyroxine product informing them that they are in violation of the law. If a company continues to manufacture an unapproved levothyroxine product, the agency may take enforcement action, such as seizing the illegal product, filing for an injunction to prevent further sale of the product, or both.

Unapproved animal drugs may not meet the agency’s strict standards for safety and effectiveness. They also may not be properly manufactured or labeled.

FDA’s Center for Veterinary Medicine (CVM) is committed to promoting and protecting animal health by ensuring safe and effective drugs are available for animals. For more information, please contact CVM’s Education & Outreach Staff at 240-402-7002 or


FDA’s Center for Veterinary Medicine

Page Last Updated: 02/25/2016
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