Pet Thyroid Health

Oct 29, 2020   Tracey Aston   Health & Wellness

The thyroid gland is part of our pet's endocrine system, and makes the hormone thyroxine necessary for proper cell function. The thyroid plays a part in metabolism, muscle and bone development, skin and coat, digestive health and temperature control. The thyroid gland is always working and helps to regulate many bodily functions by constantly releasing hormones into the bloodstream.

Hypothyroidism is the most common endocrine disorder in pets and occurs when they body doesn't release enough hormones.  Hypothyroidism is often diagnosed in senior pets, but can happen at any time in a pet's lifetime. Symptoms of hypothyroidism include: lethargy, exercise intolerance, mental dullness, weight gain without a change in appetite, obesity, cold intolerance, skin and coat changes like increased hair thinning and loss, and dry, flaky skin.  Due to the thyroid's part in metabolism and heart health, severe cases of untreated hypothyroidism can lead to seizures and heart and blood vessel problems.  The good news for pets with hypothyroidism is it's extremely treatable with medication, most often Levothyroxine.

Aversive training equipment like prong or choke collars can actually damage the thyroid gland from the constant pressure the put on a pet's neck and over time the body can't repair the damage to the thyroid gland, leading to hypothyroidism.

Hyperthyroidism is the opposite of hypothyroidism and occurs when your pet's body produces too much of the thyroid hormone. Hyperthyroidism if much more common in cats than dogs, but both can be affected.  Thyroid carcinoma, an aggressive type of cancer, can cause hyperthyroidism in dogs. If your pet is diagnosed with hyperthyroidism, it's important to speak with your vet about their condition. Symptoms of hyperthyroidism include, weight loss, hyper-excitability, increased appetite, increased thirst, increased urination, vomiting, diarrhea, tachycardia (fast heart rate) and heart murmurs.  Oral medication is used to treat hyperthyroidism.

As mentioned above, thyroid carcinoma can lead to hyperthyroidism, but not all causes of thyroid enlargement are cancerous. Some cases of thyroid enlargement are caused by goiters.  Goiters are completely benign, but do signal a veterinarian that there may be an underlying cause.  Goiters occur when the thyroid and pituitary gland are not functioning properly.  Most goiters will go away on their own or after oral treatments are started; those that are causing a pet distress can be removed surgically.

In regards to both Hypothyroidism and Hyperthyroidism, medication is usually the first line of treatment.  If your pet has been prescribed thyroid medication by your vet, it's crucial that the medication be taken directly as prescribed and as close as possible to the same time every day.  Accidents happen and one missed dose shouldn't put your pet at risk, but continued missed dosages can cause issues for a pet, including seizures.

If you feel you pet may have a thyroid condition, speak to your veterinarian about getting a blood test.  Total T4 (thyroxine) circulates in the blood as both how much hormone is attached to proteins in the blood and how much circulates freely within the blood stream. Total T4 measures both forms of the hormone in a blood sample.  Free T4 (free thyroxine) measures the amount of the free thyroxine hormone in a blood sample.  Endogenous TSH (thyrotropin) is produced by the pituitary gland and in cases of hypothyroidism, the concentration of TSH may be increased as the pituitary tries to stimulate the thyroid gland. TSH can be measured in a blood sample but the result needs to be interpreted along with a simultaneously measured total T4 or free T4 result.

As the thyroid is responsible for many of the body's functions, it's important to speak with your vet about your pet's thyroid health if you notice any of the symptoms above.  With early diagnosis and proper medication, many pets with thyroid conditions can live long, healthy lives.