Influence of medications on thyroid function in dogs: An update.

Area of Science:

• Veterinary Medicine
• Endocrinology
• Pharmacology

Background:

• Thyroid function tests are essential for diagnosing thyroid disorders in dogs.
• Medications can significantly impact thyroid hormone physiology, potentially leading to erroneous test results.
• Previous reviews on this topic were published over 20 years ago.

Purpose of the Study:

• To review the effects of various drugs on canine thyroid function tests.
• To update veterinarians on recent research concerning drug-induced alterations in thyroid hormone levels.
• To emphasize the importance of recognizing these effects to prevent misdiagnosis.

Main Methods:

• Literature review of studies published since the last comprehensive review.
• Analysis of research on specific drugs including amiodarone, zonisamide, inhalant anesthetics, clomipramine, trilostane, toceranib, glucocorticoids, sulfonamides, phenobarbital, and nonsteroidal anti-inflammatory drugs.
• Synthesis of findings related to drug impacts on thyroid hormone synthesis, secretion, distribution, and metabolism.

Main Results:

• Several drugs, including amiodarone, zonisamide, and inhalant anesthetics, have been shown to alter thyroid function tests in dogs.
• Other evaluated drugs such as clomipramine, trilostane, and toceranib also demonstrate effects on thyroid hormone parameters.
• Recent research highlights the impact of glucocorticoids, sulfonamides, phenobarbital, and NSAIDs on thyroid function tests.

Conclusions:

• Awareness of drug-induced changes in thyroid function tests is critical for accurate diagnosis in veterinary medicine.
• Failure to consider these drug effects can lead to misdiagnosis of hypothyroidism.
• Avoiding unnecessary treatment requires a thorough understanding of how medications influence thyroid hormone levels.