Hypothyroidism in Dogs - Symptoms, Treatment, and Management

Hypothyroidism in Dogs: Symptoms, Treatment, and Management

Explore the essential aspects of hypothyroidism in dogs, including its symptoms, diagnosis, treatment options, and how to manage this thyroid disorder for the wellbeing of your pet.

Table of Contents

Hypothyroidism is a common endocrine disorder affecting dogs, characterized by an underactive thyroid gland which fails to produce sufficient thyroid hormones. These hormones, thyroxine (T4) and triiodothyronine (T3), are crucial for regulating metabolism and affect various bodily functions. When their levels drop, it can lead to a range of symptoms and health issues. This article delves into the signs, causes, diagnosis, treatment, and management of hypothyroidism in dogs, offering pet owners and enthusiasts a comprehensive understanding of this condition.

Understanding Hypothyroidism in Dogs

Hypothyroidism typically occurs in middle-aged dogs, with certain breeds like Golden Retrievers, Doberman Pinschers, and Irish Setters being more predisposed. The condition is rare in toy and miniature breeds. It usually results from either lymphocytic thyroiditis, an autoimmune condition leading to the destruction of the thyroid gland, or idiopathic thyroid gland atrophy, where the glandular tissue is replaced by fat tissue. Both lead to a decrease in hormone production.

Signs and Symptoms of Hypothyroidism in Dogs

The symptoms of hypothyroidism in dogs can be subtle and gradual, making early diagnosis challenging. Common signs include:

  • Weight Gain: Unexplained weight gain without an increase in appetite is one of the hallmark signs.
  • Lethargy: Affected dogs often show less interest in activity and may seem tired more often.
  • Skin and Coat Problems: Dry skin, hair loss, and a dull coat are common. The hair loss often occurs symmetrically on both sides of the body.
  • Cold Intolerance: Dogs with hypothyroidism may seek out warm places and have difficulty tolerating colder temperatures.
  • Reproductive Issues: Females may have irregular heat cycles, while males may show a lack of libido.
  • Other Issues: Include facial puffiness, muscle loss, slow heart rate, and behavioral changes such as aggression or depression.


Diagnosing hypothyroidism in dogs involves a thorough physical examination by a veterinarian and a review of the dog’s medical history and symptoms. Blood tests are crucial for confirming the diagnosis. These tests measure levels of thyroid hormones in the blood. The most common tests include:

  • Total T4 (TT4): This is often the initial screening test. Low levels may suggest hypothyroidism.
  • Free T4 (FT4) by Equilibrium Dialysis (ED): This test is more specific and is less affected by non-thyroidal illness or medications.
  • Thyroid-Stimulating Hormone (TSH) Assay: High levels of TSH combined with low levels of T4 can confirm hypothyroidism.
  • T3 and T4 Autoantibodies: The presence of these antibodies can indicate an autoimmune cause of the thyroid dysfunction.

Treating Hypothyroidism in Dogs

The treatment for hypothyroidism in dogs is hormone replacement therapy, typically involving a daily oral dose of synthetic thyroxine (levothyroxine). The dosage and treatment plan are tailored to the individual dog, based on weight, the severity of symptoms, and hormone levels. Regular follow-up visits are necessary to monitor the dog’s response to treatment and adjust the dosage as needed. With appropriate treatment, most dogs with hypothyroidism can lead a normal, active life.

Management and Prognosis

Management of hypothyroidism requires lifelong medication, along with regular veterinary check-ups to ensure the hormone levels remain within a normal range. The prognosis for dogs with hypothyroidism is generally excellent, as the condition is typically manageable with medication. Owners should be aware of the potential side effects of hormone therapy, which can include symptoms of hyperthyroidism, such as increased heart rate, excessive thirst, and hyperactivity, if the dose is too high.

It’s also essential for owners to maintain a healthy lifestyle for their pets, with a balanced diet and regular exercise to avoid obesity and other health issues. Adjustments to the dog’s diet and exercise regimen may be necessary to accommodate the slower metabolism associated with hypothyroidism.


Hypothyroidism in dogs is a manageable condition with prompt diagnosis and appropriate treatment. Understanding the signs and symptoms can help pet owners seek timely veterinary care, leading to a better quality of life for their pets. With ongoing management, most dogs with hypothyroidism can enjoy a normal lifespan and continue to be a joyful part of the family. Awareness and education about this condition are key to ensuring the health and well-being of our canine companions.

Join our Mailing list!

Get free coupons, exclusive deals & special discounts!

Newsletter Subscription

Share this post
Related Articles

Join our Mailing list!

Get free coupons, exclusive deals & special discounts!

Newsletter Subscription

Disclaimer and Agreement