What are the symptoms of hypothyroidism in dogs?

Hypothyroidism in dogs is a common condition in which the thyroid gland does not produce adequate levels of thyroid hormones. Thyroid hormones affect multiple body systems, so symptoms can be wide-ranging, including unexplained weight gain, lethargy, exercise intolerance, and skin and coat changes. If you have a dog, read on to discover:

• What is hypothyroidism?
• How do I know if my dog has hypothyroidism?
• How did my dog get hypothyroidism?
• How is hypothyroidism in dogs diagnosed and treated?

Hypothyroidism is a progressive disease, causing worsening symptoms over time in untreated dogs. When treated, hypothyroidism carries a good prognosis, with most treated dogs having a normal life expectancy.

Hypothyroidism is a condition in which the thyroid gland, located in the neck, does not produce adequate amounts of thyroid hormones. As a result, the circulating levels of thyroid hormones are low throughout the body. Thyroid hormones are responsible for maintaining metabolism, which allows bodily organs to function properly. Hypothyroidism is one of the most common endocrine diseases in dogs, but it can be very difficult to diagnose. Thyroid hormone levels naturally fluctuate in response to various triggers, and other medical conditions unrelated to hypothyroidism can lead to low thyroid hormones in the body. Diagnosis of hypothyroidism can be challenging, but treatment is relatively straightforward, and the condition can be well managed throughout the dog’s life.

Symptoms of hypothyroidism can be mild and vague, especially in the beginning stages of the disease. As a result, they are easy to overlook or attribute to another medical condition. Clinical signs of canine hypothyroidism include:

• Unexplained weight gain
• Lethargy or lowered activity levels
• Cold intolerance
• Hair loss
• Increased skin pigmentation
• Skin thickening
• Dull, dry skin and coat
• Recurrent skin or ear infections

“A common sign of hypothyroidism in dogs is unexplained weight gain or difficulty losing weight in spite of a healthy calorie intake and sufficient exercise. This is due to the lowered metabolic rate commonly seen in dogs with hypothyroidism,” explains Dr. Jo Myers, a veterinarian on the Vetster platform. “Dogs that are overweight or obese due to too much food or too little exercise do not necessarily have hypothyroidism.”

If hypothyroidism is left untreated, rare but severe symptoms can present, such as:

• Collapse
• Seizures
• Paralysis
• Weakness
• Difficulty walking
• Difficulty breathing

These symptoms are emergencies and require immediate veterinary care. Hypothyroidism that is detected early and well managed is rarely life-threatening. In rare cases, untreated hypothyroidism may result in fatal complications.

There are two main types of hypothyroidism in dogs: lymphocytic and idiopathic. Lymphocytic thyroiditis, or primary hypothyroidism, is the most common, and occurs when the dog’s immune system attacks the thyroid gland. Idiopathic thyroid gland atrophy has no known cause. The thyroid tissue disintegrates and is replaced by fat or connective tissue for no known reason. Other rare causes of hypothyroidism include:

• Thyroid cancer
• Pituitary gland disease
• Congenital defects of the thyroid
• External trauma to the neck

Hypothyroidism is a common condition in dogs, especially in seniors. Senior or middle-aged dogs are most at risk for developing the condition. Medium- to large-breed dogs are more often diagnosed, and some breeds are predisposed to hypothyroidism, including:

• English and Irish setters
• Dalmatians
• Boxers
• Huskies
• Golden retrievers
• Doberman pinschers

Male and female dogs are equally affected by hypothyroidism, but the condition may be more prevalent in sterilized dogs of both sexes (spayed females and neutered males).

Getting a definitive diagnosis of hypothyroidism can be difficult. Though the condition is common, symptoms are often vague and sporadic and can mimic other health issues. Many other health conditions can cause the total thyroid hormone (TT4) level to be low on blood work, even if the dog does not have hypothyroidism. After discussing the patient’s presenting symptoms and history, and if there is suspicion of hypothyroidism, a vet may recommend a thyroid profile blood test in order to confirm or rule out hypothyroidism. This test measures current levels of thyroid hormones in the body and the hormone that stimulates thyroid hormone production. Diagnostic imaging of the thyroid gland or other diagnostic tests may be recommended to rule out other conditions and help confirm hypothyroidism. An accurate diagnosis is required for hypothyroid treatment.

The treatment of hypothyroidism in dogs most often involves daily hormone replacement therapy in a pill given once or twice a day at home. Regular blood tests are required to continuously monitor the dog’s thyroid hormones, and treatment may be adjusted throughout a dog’s life. Clinical signs may take a few months to improve based on response to treatment.

Can hypothyroidism be cured?

Hypothyroidism is a lifelong condition that cannot be cured. However, treatment is typically very effective and allows an affected dog to have a good quality of life. Treatment is lifelong. The prognosis of hypothyroidism is generally good with early diagnosis, continued treatment, and monitoring with a veterinarian.

Talk to a veterinarian any time you notice physical or behavioral changes in your dog. It’s important not to brush off minor symptoms as a normal part of aging in seniors. Routine wellness checks with a vet are important because hypothyroidism is so common in senior dogs. Many other endocrine disorders and health conditions have similar symptoms to hypothyroidism, so reaching an accurate diagnosis may take additional diagnostics. Visit a veterinarian for diagnostic testing and talk to them about hypothyroidism. If you are concerned about your dog’s symptoms or how to manage your dog’s hypothyroidism, you can connect with an online vet through Vetster at any time.

What are the common symptoms of hypothyroidism in dogs?

Common symptoms of canine hypothyroidism include unexplained weight gain despite portion control and regular exercise, lethargy, intolerance to cold weather, exercise intolerance, and skin or coat abnormalities. Symptoms are often mild and intermittent in the early stages of the disease.

What triggers hypothyroidism in dogs?

Primary hypothyroidism occurs when the dog’s immune system attacks the thyroid gland. Other rare causes include thyroid tumors, pituitary gland disease, external trauma, and congenital defects. Some cases of hypothyroidism are idiopathic, meaning the condition has no known cause.

How do dogs act when they have thyroid problems?

A dog with hypothyroidism may suddenly gain weight, become lethargic, and seek warm places to rest or dislike the cold more than usual. Hair may become thin or fall out, and the skin may show changes as well. In severe cases, they may have trouble walking or have seizures.