Dog Thyroid Testing

Hypothyroidism, hyperthyroidism and thyroid cancer are the most common thyroid disorders in dogs, with hypothyroidism being the most prevalent of these. Thyroid status can affect many issues in the dog's health, including weight, digestion, energy levels, heart rate, and skin and fur health, and tests can play a critical role in both diagnosing and treating thyroid problems.

  1. Definitions

    • The dog's thyroid gland is part of the endocrine system and sits under the skin at the base of the neck. It produces thyroid hormones that control the metabolism and affect every cell and system in the body. When the dog is exhibiting signs and symptoms of a thyroid disorder, it is important to have the proper medical tests completed by the veterinarian and to receive the proper diagnosis of any thyroid disorders.

    Hypothyroidism Tests

    • Hypothyroidism exists when the dog's thyroid gland does not produce normal amounts of thyroid hormones. Symptoms in dogs that can send pet owners to the vet for thyroid testing include weight gain, low energy, shedding and digestive problems. Blood tests play a big role in diagnosing and managing hypothyroidism in dogs, and these tests include thyroid stimulating hormone (TSH), T4, T3, free T4 and TSH stimulation test. If diagnosed as being hypothyroid, a dog also needs to have regular tests to monitor his dosage of thyroid hormone replacement medication.

    Hyperthyroidism Tests

    • Hyperthyroidism in dogs involves the overproduction of thyroid hormones and, according to Dog Health Handbook, thyroid cancer is its most common cause. Possible symptoms include weight loss, increased heart rate, shortness of breath and anxiety. Tests for hyperthyroidism measure blood levels of thyroid hormones, such as thyroid stimulating hormone (TSH), T4, T3, free T4 and TSH stimulation test. Additional tests include urinalysis, complete blood count and scintigraphy. Although not a laboratory test, the veterinarian often assesses the dog's thyroid by feeling it with her hands.

    Thyroid Cancer Tests

    • Thyroid cancer in dogs is not common. Symptoms include weight loss, increased appetite, nervousness and increased urination, although in some cases not many symptoms are present. The veterinarian can feel the thyroid with his hands to see whether it is enlarged and also can perform an ultrasound to assess whether the dog could have thyroid cancer. If the vet suspects that the dog has thyroid cancer, he typically uses a tissue biopsy to aid in making a diagnosis.

    Considerations

    • Although laboratory tests can play a critical role in diagnosing thyroid disorders in dogs, their results can sometimes be inaccurate. Nonetheless, assessing the dog frequently with tests throughout the treatment of her thyroid disorder is critical to ensuring proper care. Symptoms also are key in forming an accurate assessment of the dog's thyroid health, in both forming the initial diagnosis and in monitoring thyroid treatment over time.