What is Hypothyroid Disease?
Hypothyroidism is when the thyroid is not functioning properly and there is a deficiency of the thyroid hormone. It is considered one of the most common hormone imbalances in dogs.
What causes Hypothyroid Disease?
Thyroid deficiency can be caused by immune-mediated destruction of the thyroid gland, by natural atrophy of the gland, by dietary iodine deficiency, or as a congenital problem. Some breeds that can be predisposed to this disease are:
Golden Retrievers, Dobermans, Irish Setters, Schnauzers, Cocker Spaniels, and Dachshunds. This does not mean that only those breeds can get it, it is possible for any breed to develop hypothyroidism.
What are the signs of Hypothyroid Disease?
Some signs you could see are: weight gain with no diet change, “rat tail” (loss of hair on tail), dry hair/skin, cold intolerant, recurrent skin infections, lethargy, and reproduction problems. The pet could have all or maybe just one symptom. Annual labwork is important for early detection.
How do we diagnose Hypothyroid Disease?
To check thyroid levels, we have to send blood from the pet to the lab. This test is called a Total T4, which is usually included in all well health screening labwork. If the Total T4 comes back low, then it could indicate hypothyroidism. If the thyroid levels come back low we do more investigating before diagnosing hypothyroidism, because some other factors could cause low Total T4. For example, some other disease or medications can cause low Total T4. If no other factors could cause it, we add on a different blood thyroid testing at the lab to confirm low levels. This test is called a Free T4. The Total T4 testing can be falsely lowered because of other non-thyroidal disease and drugs, and Free T4 levels are less subject to be falsely lowered. Thyroid ultasonography and biopsy can also be performed for diagnosing, but owner’s rarely do these diagnostics for the pet.
How do you treat Hypothyroid Disease?
Once the pet has been diagnosed with hypothyroidism, then they will need to be on a LIFE LONG supplement to replace the hormone. The pet will need to take a medication twice daily for the first 4-8 weeks, then more blood will need to be taken to check the T4 levels again. We do this so that we know the pet is on the right dose for them. If the levels come back too low or even too high we can easily change the dose so that it is perfect for them. Any symptoms should start to resolve with the correct dosing, and the pet should become their happy self again. Once the pet is regulated we check labwork every year to be safe (or earlier if the pet starts having issues).
We have to check the levels frequently because of two main reasons. The first is that we are not giving enough of the supplement, which causes all the symptoms to still be present and ongoing low thyroid levels can start to disrupt other organ functions. The second is that we can start to cause the opposite of hypothyroid disease, hyperthyroid disease. Hyperthyroid disease is increased thyroid hormone.
Once a pet has been diagnosed with Hypothyroid Disease and is regulated properly with a daily supplement, they can live happy healthy lives.
By: Jamie McAfee
Common Diseases of Companion Animals, By Alleice Summers