Thyroid Function Test Flashcards
What are the thyroid function tests in the dog?
Total T4 - sensitive for hypothyroidism but not specific
Free T4 - Highly sensitive and specific
TSH - insensitive, very specific
When should you not test a dog for thyroid function?
When they have a non-thyroidal illness (need to clear that up first)
What are some signs of hypothyroidism?
Excessive shedding, tires more when exercising, truncal alopecia, mild obesity
Why can a dogs T4 be elveated?
Hyper or hypothyrodism
Is hyperthyroidism common in dogs? What may cause it?
Diet, iatrogenic, thyroid carcinoma
What can cause hypothyroidism in a dog with elevated T4?
Interferance with autoantibodies
autoimmunehyroiditis
Drugs:
Phenobarbitol, sulfonamide, clomipramine, glucocorticoids, NSDIA
other illness
Lymphocytic thyroiditis
What should you always consider when interperting a thyroid test?
Clinical signs
Factors like Breed, drugs, NTI
Consider with other test results
What are autoantibodies to T4 and T3? Are they common?
Indicate immune thyroiditis
50% hypothyroid cases
Interfere with assay
Dont indicate hyper or hyp
When treating with levothyroxine, when is the peak effect of the drug?
4-6 hr post treatment
What are some reasons you may test a dog for hypothyroidism that are not the classical signs?
Megaesophagus
High cholesterol
How do you know it autoantibodies are at play?
Can test for them in blood
What is the most common disease for a cat with vomiting, PU/PD and weight loss with a good appetitie?
Hyperthyroidism
