ALISON LAURIE-CHALMERS: Tackling a common health issue in larger dogs
“Roly” was a lovely, bouncy Boxer dog. He was brought into the surgery as he had recently become dull and lethargic. He was noticeably gaining weight despite being on the same diet and had developed large patches of hair loss over his back.
He underwent tests, and it was soon confirmed that he had hypothyroidism. This is a common endocrine disease in dogs that results in a decreased production of thyroid hormones.
These are produced by the thyroid glands on either side of the lower neck. Thyroid hormones serve an important role in a body’s metabolism. When the thyroid glands are not producing enough hormones, all the body’s functions slow down.
The two most common causes of hypothyroidism in dogs, accounting for more than 95 per cent of cases, are inflammation of the thyroid gland (lymphocytic thyroiditis) and degeneration of the thyroid gland (idiopathic thyroid gland atrophy), and there does seem to be a genetic predisposition. Fortunately, thyroid tumours are uncommon in dogs.
Hypothyroidism is most common in middle-aged dogs with medium-to-large breed dogs being more commonly affected. Golden retrievers, dobermans, boxers, dachshunds, miniature schnauzers, cocker spaniels, and Irish setters are among the breeds more predisposed.
Dogs with hypothyroidism can show one or more clinical signs: weight gain, often without an increase in appetite; lethargy and laziness; heat-seeking behaviours, preferring to lie near a heat source to try and stay warm; chronic skin and ear infections; dry and brittle hair with coat thinning; hair loss and an increased pigmentation of the skin.
Some other symptoms are reproductive problems, and issues with their nervous systems, including weakness and dragging of their hind legs. Some cases may have lipid deposits on the surface of their eyes, or can develop “dry eye”, where they don’t produce enough tears. Also, some dogs have a swelling of the facial skin causing the skin to droop.
Hypothyroidism is diagnosed with specific blood tests to determine your dog’s hormone levels.
It is manageable, but not curable. It is treated with a lifelong thyroid hormone replacement therapy, a synthetic form of the hormone that your dog is missing. Your vet will select the appropriate dosage of supplementation for your dog. Thereafter blood levels should be checked in one month to ensure no dosage changes are required.
Once an appropriate supplementation is reached, these levels are generally checked every six months. The tolerance of supplement medication may change over time, so your dog may occasionally require dosage adjustments.
It is important that your dog not be given too little or too much thyroid hormone, and it is recommended that you have your dog’s blood thyroid levels checked every six months. After piloting treatment, once your dog’s thyroid levels have been restored, your dog may lose any excess weight and they will likely have more energy. While it can take many months for hair to grow back, there will be an improvement in their skin and coat over time.
Dogs with hypothyroidism can live normal, healthy lives when the disease is managed correctly. While it is not curable, it has an excellent prognosis and patients generally respond very well to treatment.
“Roly “responded well and was soon back to his normal, bouncy self.
If your dog has any of the symptoms, arrange an appointment with your vet for an initial check-up, as there can be help available.
n Alison Laurie-Chalmers is a senior consultant at Crown Vets.
