What Does It Mean If a Dog Has Low T4?

One health ailment that is relatively commonplace in the canine world is hypothyroidism, a type of endocrine disorder. Hypothyroidism is triggered by insufficient output of thyroxine, which is a thyroid hormone. Although hypothyroidism is prevalent in canines, it's extremely rare in felines, who tend to experience hyperthyroidism instead.


Thyroid Gland

The thyroid gland is situated over the throat, under the voicebox. This wee gland is responsible for transferring iodine into two key thyroid hormones, one of which is the aforementioned thyroxine, or T4. The other hormone is triiodothyronine, T3. These hormones travel within the blood and regulate metabolism. If your pooch has hypothyroidism, that means that his metabolism is operating in a slow manner. Thyroxine is vital for proper growth and development of canines' bodies, as well.

Low T4

If you're concerned that your doggie might have hypothyroidism, a trip to the veterinarian is in order. A veterinarian can perform a blood test on your pet to evaluate his blood's T4 presence. If your cutie is experiencing thyroid gland issues, he'll have a low T4. Despite that, a low T4 is not 100 percent a guarantee of hypothyroidism, as it sometimes can point to other things. Because of this, veterinarians generally conduct other examinations, such as ones that analyze amounts of T3.


Medicine use can sometimes make dogs show low T4 results, as well. Some examples of these medications are various antibiotics, corticosteroids and sulfonamides. For example, roughly six weeks of taking sulfonamide can lead to reduced T4 levels in canines.

Breeds and T4 Levels

Certain canine breeds naturally possess low T4 examples. Sled dogs and greyhounds are part of this category. Because of these kinds of factors, it's crucial to take many things into consideration in looking at the results of T4 tests.

Key Hypothyroidism Symptoms

The quicker you pick up on signs of hypothyroidism in your fluffball, the quicker you can get him to the veterinarian for T4 testing. Some often telling symptoms of canine hypothyroidism are exhaustion, shifts in behavior, balance issues, excessive weight gain, timid behavior, sluggish growth of fur, inability to manage cold weather, dandruff, zapped energy or enthusiasm, excessive shedding, anemia and constipation. Note, too, that some dogs with hypothyroidism go for years at a time without displaying any hints of it.

By Naomi Millburn

About the Author
Naomi Millburn has been a freelance writer since 2011. Her areas of writing expertise include arts and crafts, literature, linguistics, traveling, fashion and European and East Asian cultures. She holds a Bachelor of Arts in American literature from Aoyama Gakuin University in Tokyo.