Low Thyroid Function in Dogs

Low thyroid function in dogs is also known as hypothyroidism, a condition that is frequently seen in canines. The thyroid glands produce thyroid hormones, and when these are in deficit, the dog has hypothyroidism which manifests through various symptoms. The thyroid function can be improved with medication and therapy.

Causes of Low Thyroid Function

The low thyroid function is a result of an issue affecting the thyroid glands, which are two small glands positioned at the base of the neck. If the thyroid glands are affected by a tumor or are injured or destroyed, the dog may have a low level of thyroid hormones. A treatment for hyperthyroidism can result in low thyroid function.

However, the activity of the thyroid glands is also influenced by the pituitary gland and the hypothalamus, so if these are in any way affected, it may influence the level of thyroid hormones. An issue with the pituitary gland of the hypothalamus accounts only for 5 percent of the hypothyroidism cases in dogs. An immune system problem can also lead to the destruction of the thyroid glands.

Symptoms of Hypothyroidism

Low thyroid function in a dog will manifest through symptoms such as:

  • Weight gain despite the low appetite, due to the fact that the metabolism is slowed down (the thyroid hormones regulate the metabolism of the pet)
  • Lethargy
  • Hair loss in patches
  • Skin problems, especially dry skin, often affected by secondary skin infections
  • Anemia
  • Increased cholesterol
  • Cold intolerance
  • Hyperpigmented areas
  • Slow heart beat

Some dogs may show no symptoms at all for a long time and display a few signs when the low thyroid function affects the rest of the body. Middle aged or older dogs are more likely to develop hypothyroidism. Spayed females and a number of breeds are more exposed to having a low thyroid function.

Diagnosing Low Thyroid Function

The thyroid function can be diagnosed with a blood test which will establish the level of the thyroid hormones (T3 and T4). The TSH levels may also be measured. The TSH stimulation test may be performed by the vet to establish if the dog has hypothyroidism.

Treatment Options

The most commonly prescribed medication for low thyroid function in dogs is thyroid hormones such as Thyroxine or Soloxine. These hormones are synthetically produced to mimic the natural canine hormones. The dosage will be established by the vet, according to the severity of the pet's condition. Some dogs may also benefit from radioactive therapy, which will stimulate the function of the thyroid glands.

The treatment may be discontinued if the dog shows signs of improvement. However, the dog will have to return to the vet clinic for periodic testing, which will establish whether the dog requires medication or not. A dog that has been diagnosed with hypothyroidism is more likely to have recurrent episodes of low thyroid function.