Sick dog lying on a sofa under a grey blanket

The opposite of hyperthyroidism in dogs, which is where too much thyroid hormone is produced.Without adequate thyroid hormone production, the dog's metabolism slows down, leading to a variety of clinical signs and symptoms, including skin issues, hair loss, and weight gain.

There are several potential causes of hypothyroidism in dogs; it can be inherited or acquired, and the condition can present in different ways depending on the severity and the specific cause. Typically, hypothyroidism is more commonly diagnosed in middle-aged dogs, but it can occur at any age, with certain breeds being more predisposed.

Fortunately, with proper diagnosis of hypothyroidism and treatment, the condition can be stabilised and the symptoms managed. This means that dogs with hypothyroidism can still lead happy, healthy lives.

What Are the Signs of Hypothyroidism in Dogs?

The hypothyroidism signs and symptoms in dogs are numerous. The symptoms often develop gradually, which makes it harder for pet owners to notice them early on. Common hypothyroidism symptoms in dogs include:

  • Hair loss/alopecia: Affected dogs often experience hair thinning or bald patches, particularly along the flanks (the sides of the body) and on the tail.
  • Weight gain: Despite decreased appetite or normal feeding habits, many hypothyroid dogs will gain weight.
  • Sluggishness or lethargy: Dogs with hypothyroidism may show less interest in playing, walking, or engaging in physical activity. They may sleep more than usual.
  • Skin changes: Skin problems in dogs with hypothyroidism are common, including dryness, thickening, or darkening of the skin (hyperpigmentation).
  • Coat texture changes: The dog's coat may become dull, brittle, and coarse.
  • Cold sensitivity: Affected dogs may seek out heat sources and appear cold even in moderate temperatures.

If your dog is showing signs of hypothyroidism, it's important to consult with a vet, as early diagnosis and treatment can help prevent further complications.

What Dogs Breeds Are Most Likely to Develop Hypothyroidism?

Hypothyroidism can affect dogs of any breed, but certain breeds are more prone to developing the condition. These breeds include:

While middle-aged dogs are most commonly affected, hypothyroidism can also be seen in older dogs or those with specific risk factors, such as obesity or previous thyroid problems.

Additionally, male dogs and dogs with a family history of thyroid disease may be more likely to develop the condition.

What Causes of Hypothyroidism in Dogs?

The underlying cause of hypothyroidism in dogs is often related to the thyroid gland's inability to produce sufficient thyroid hormones. But the three most common types of the condition are:

  • Primary hypothyroidism
  • Secondary hypothyroidism
  • Tertiary hypothyroidism

Primary Hypothyroidism

The most common form of hypothyroidism in dogs. It can be further divided into two main causes, both of which are equally common causes of primary hypothyroidism:

  • Lymphocytic thyroiditis: An immune-mediated condition where the dog's immune system attacks and destroys the thyroid gland, preventing it from functioning properly.
  • Idiopathic thyroid gland atrophy occurs when there's a loss of cells, causing the thyroid gland to shrink and lose its ability to produce thyroid hormones. There's no immune system involvement in the loss of cells. Other causes include medication, low iodine levels, tumours and inherited causes. 

Secondary Hypothyroidism

A much rarer cause, occurring in less than 5% of cases. It occurs when the pituitary gland (located in the brain) fails to produce enough thyroid-stimulating hormone (TSH), which is necessary for stimulating the thyroid to produce hormones. Secondary hypothyroidism is often due to pituitary tumours or congenital issues.

Tertiary Hypothyroidism

 An extremely rare form of hypothyroidism that occurs due to a lack of thyrotrophin-releasing hormone (TRH). This is another hormone that helps regulate thyroid hormone production in the body. This cause isn't fully understood.

Spotting the Uncommon Symptoms Of Hypothyroidism in Dogs

If your vet suspects hypothyroidism, they'll conduct a thorough physical examination and may recommend several tests to confirm the diagnosis. The most common diagnostic tests include:

  • Blood tests to measure the levels of thyroid hormones (T4) and thyroid-stimulating hormone (TSH) in the blood. Abnormal levels indicate an issue with thyroid function.
  • Thyroid function tests to measure total thyroxine levels (thyroid hormone), including Free T4, Total T4, and TSH. All of which help assess thyroid function more precisely.
  • Stimulation tests that stimulate the thyroid gland and assess how it responds.
  • A skin biopsy may be recommended due to a high incidence of hypothyroidism in dogs causing skin problems. This will also help to rule out other conditions.
  • Diagnostic imaging may be recommended to assess the thyroid gland or surrounding tissues if a thyroid tumour is suspected.

In some cases of hypothyroidism in dogs, further tests or referrals to specialists may be necessary, especially if there is a suspected thyroid tumour or underlying health issues contributing to the condition.

Following a diagnosis, treatment is usually started to stabilise the patient. 

How to Treat Hypothyroidism in Dogs

Hypothyroidism is generally managed by replacing the missing thyroid hormones with synthetic thyroid hormones. Medication helps normalise the dog's metabolism and alleviate symptoms.

The treatment plan typically involves the following:

  • Thyroid hormone replacement: The most common treatment is synthetic levothyroxine, which replaces the missing thyroid hormone. The dosage will be determined based on the dog's weight, age and overall health, and it may need to be adjusted over time.
  • Diet and feeding: Dogs with hypothyroidism may need to be carefully managed in terms of diet, especially if they're overweight. Your vet will help you develop a weight management plan.
  • Regular monitoring: After starting treatment, your vet will monitor the dog's thyroid hormone levels through blood tests to ensure they're within the optimal range. It may take several adjustments to achieve the correct dosage.

In rare cases where a thyroid tumour is involved, surgery or referral to a specialist may be necessary, though hormone replacement therapy will still be needed afterwards.

Once treatment is started, it's crucial to continue regular monitoring to ensure your dog's thyroid levels remain stable. You and your vet will work together to monitor your dog for any signs of recurrence, such as lethargy, weight gain, or skin problems, which may indicate the need for dosage adjustments.

Hypothyroidism is a common condition in dogs and one that's usually well-controlled with medication and monitoring. Most dogs with hypothyroidism can lead full, happy lives.

If you notice any symptoms of hypothyroidism in your dog, such as hair loss, weight gain, or lethargy, it's essential to consult your vet. Early diagnosis and treatment are key to managing the condition effectively and improving your dog's quality of life.

Everypaw Dog Insurance

Everypaw's Dog Insurance comes with 24/7 unlimited access to vets and vet nurses that can help with your pet's health, care, nutrition and behaviour. So you can rest assured your pup will be well looked after.

Get a quote

 

Content provided from Vetstream's Vetlexicon Canis - www.vetlexicon.com/canis 

Vetlexicon is the world’s largest peer-reviewed online clinical reference source. All our content is written and peer-reviewed by over 1,000 of the world’s leading veterinarians, ensuring relevance, accuracy and quality.

;