Changes in thyroid hormone concentrations over time in dogs with autoimmune thyroiditis.

Area of Science:

• Veterinary Endocrinology
• Canine Internal Medicine

Background:

• Subclinical thyroiditis in dogs is characterized by elevated thyroglobulin autoantibodies (TgAA) without overt clinical signs.
• Long-term monitoring is essential to understand disease progression and outcomes.

Purpose of the Study:

• To investigate long-term changes in thyroid hormone concentrations in dogs diagnosed with subclinical thyroiditis.
• To assess the progression of autoimmune thyroiditis and the risk of developing hypothyroidism.

Main Methods:

• Retrospective analysis of 125 dogs with subclinical thyroiditis.
• Serum samples collected over a mean interval of 3.9 years.
• Utilized data from the Orthopedic Foundation for Animals Canine Thyroid Profile.

Main Results:

• 30% of dogs progressed to hypothyroidism or received thyroxine treatment.
• 50% maintained positive/equivocal TgAA while remaining euthyroid.
• 14% became TgAA negative and remained euthyroid.

Conclusions:

• Dogs with subclinical thyroiditis and positive TgAA face a persistent risk of autoimmune thyroiditis or progression to hypothyroidism.
• Annual monitoring of thyroid function is recommended for dogs with subclinical thyroiditis, or sooner if clinical signs change.