Thyroid Problem in Dog. Is My Dog Fat?

Hypothyroidism in Dogs

Hypothyroidism in Dogs

The thyroid gland, a vital hormone gland located in the neck, produces hormones that play a major role in metabolism, growth, and body development.

Moreover, dogs with thyroid problems typically have low production of thyroid hormones. Conversely, overproduction of thyroid hormones in dogs is rare and usually associated with cancer. Fortunately, thyroid cancer is uncommon in dogs. Additionally, hypothyroidism is usually caused by inflammation or shrinkage of the thyroid glands. It occurs more commonly in medium to large breed dogs, usually in middle-aged dogs. Breeds commonly affected include Golden Retrievers, Doberman Pinschers, Irish Setters, Miniature Schnauzers, Dachshunds, Cocker Spaniels, and Airedale Terriers.

Clinical Signs:

Many of the clinical signs, such as mental dullness, lethargy, exercise intolerance, and weight gain despite a normal appetite, directly result from slowing cellular metabolism. The most common signs of low thyroid function in dogs include hair loss, dull hair coat, excess shedding or scaling, thickening of the skin, weight gain, reduced activity, and reproductive disturbances in intact dogs, as well as reduced ability to tolerate the cold. Hair loss, not associated with itchiness, usually occurs bilaterally symmetrically and may involve various parts of the body. Alterations in the skin and coat sometimes accompany hyperpigmentation.

Occasionally, hypothyroid dogs may also develop skin infections (pyoderma), which may be itchy and result in sores on the body. The accumulation of mucopolysaccharides can cause the muscles of the face to droop, giving the dog a ‘tragic’ facial expression. Though less common, neurologic disorders associated with hypothyroidism in dogs include dilation of the esophagus (megaesophagus) causing regurgitation, laryngeal paralysis, facial nerve paralysis, and vestibular disease.


In routine wellness blood tests, your vet may notice mild anemia and increased levels of cholesterol in dogs with hypothyroidism. However, hypothyroidism is probably one of the most overdiagnosed diseases in dogs. Various nonthyroidal illnesses can lead to low serum thyroid hormone measurements in euthyroid dogs or cats. If you notice one or more of these clinical signs, it’s crucial to talk to our vet in Newmarket. Our veterinarian may need to run diagnostic tests such as measuring serum concentrations of total T4, free T4, and/or TSH for the diagnosis of canine hypothyroidism

How is Canine Hypothyroidism Treated?

The treatment of hypothyroidism involves giving oral replacement hormone for the rest of the dog’s life. Initially, thyroid hormone is usually administered twice daily. Once the hair coat begins to improve, some dogs can be maintained on once-daily medication. Almost all hypothyroid dogs receive T4 (levothyroxine or L-thyroxine). T4 is converted to T3 by the body. However, a few dogs are unable to make this conversion and require T3 medication.

It typically takes 4 to 6 weeks for the hair to regrow. If you have concerns about your dog’s weight or suspect your dog is hypothyroid, it’s essential to take your dog to our veterinarian in Newmarket at Brooker Ridge Animal Hospital. We specialize in treating hypothyroidism and other related health issues that could cause weight gain. Call 905-898-1010 to schedule your pet’s appointment.