When a dog’s thyroid gland doesn’t produce enough hormones, a condition called hypothyroidism occurs. Middle-aged and older dogs are most commonly affected. Thyroid hormones help regulate many internal functions, such as metabolism and heart rate. When these hormones are low, vital functions are impaired and symptoms appear. Fortunately, with early detection and treatment, most hypothyroid dogs have a normal life expectancy.
Causes of Hypothyroidism in Dogs
Lymphocytic thyroiditis, an immune-mediated disease, is the most common cause of hypothyroidism in dogs. This occurs when the immune system attacks and destroys the thyroid gland, leading to significant inflammation and low hormone production. It is not known why the immune system decides to attack the thyroid gland, but it is believed to be hereditary.
Hypothyroidism in dogs can also occur due to atrophy of the thyroid gland. During this process, the functional tissue of the thyroid gland is replaced by fat. Veterinarians also don’t know why this process occurs.
A pituitary tumor is another cause, but it is extremely rare. The pituitary gland is located at the base of the dog’s brain and is responsible for secreting thyroid-stimulating hormone. In dogs with a pituitary tumor, this process is impaired and the thyroid gland is not stimulated. Thyroid hormones are therefore not produced.
Symptoms of Hypothyroidism in Dogs
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Hypothyroidism causes many symptoms in dogs, which may include the following:
- Weight gain despite a normal appetite
- Fat accumulation around the shoulders, neck and hindquarters
- Lethargy
- Dull hair coat
- Slow hair regrowth
- Scaly and/or thickened skin
- Patches of alopecia (hair loss)
- Slow heart rate
- Cold intolerance
- Recurrent skin and ear infections
- Fertility problems
- Reduced tear production (dry eye)
- Nerve abnormalities
Dogs with hypothyroidism may have high cholesterol, high fat, and mild anemia on blood tests.
How to Treat Hypothyroidism in Dogs
Dogs suffering from hypothyroidism require oral supplementation of a synthetic thyroid hormone called levothyroxine. This medication is administered daily and is relatively inexpensive. The dose, which is determined by the the weight of the dog, may change over time depending on its response to treatment. Periodic blood tests help the veterinarian evaluate hormone levels and adjust the dose if necessary. Supplementation is necessary for the rest of the animal’s life.
Since hypothyroid dogs are already prone to high cholesterol levels, switching to a low fat kibble is beneficial. omega-3 fatty acids also promote healthier skin and coat. Your veterinarian can recommend the best type of food to meet your dog’s specific needs.
Life expectancy
Hypothyroidism is not a curable disease. However, most healthy hypothyroid dogs live long, happy lives with proper monitoring and treatment. Dogs with other health problems, such as cardiac disease or kidney disease, may have a shorter lifespan due to difficulty managing hypothyroidism alongside concurrent illness.
If left untreated, hypothyroidism leads to poor quality of life, increased risk of complications, and reduced lifespan. Early diagnosis ensures your pet gets the treatment they need to be happy and healthy. If you notice signs of hypothyroidism in your dog, take him to the veterinarian for evaluation.