Hypothyroidism and Your Dog

While cats are at risk of hyperthyroidism, our dogs tend to get hypothyroidism.  It can go undiagnosed, as many symptoms can be brushed aside as "he's just getting older".  Slowing down, and especially weight gain; owners tend to assume their metabolism is slowing down and the weight gain is normal. 

Hypothyroidism is generally caused by the destruction of the thyroid gland, and is referred to as an "underproducing thryoid", as it makes less of the hormones T3 and T4.  The thyroid controls body metabolism, and many other functions in the body such as protein production.  Protein in and of itself is essential to pretty much all vital body functions.  Your dog could have an autoimmune disorder which impacts it's thyroid, but it can merely due to degeneration of the gland with age.  This condition is mostly seen in older dogs due to this fact.  Some pre-disposed breeds include Cocker Spaniels, Golden Retrievers, Dobermans, Irish Setters, Dachshunds, and spayed females.

The general clinical signs include weight gain without an increased appetite, lethargy, decreased energy level, weakness, exercise intolerance, slowed heart rate (bradycardia), and cold intolerance/"heat seeking" behavior.  Dull, dry, coarse haircoat, thickened skin, bilateral hair loss, and secondary skin infections can all impact the skin.  You can see why someone may dismiss these symptoms as just "he's getting old".  Your vet will likely want to run a thyroid test on your older dog; let him.  Hypothyroidism is effectively treated with daily oral meds.  It's very treatable, but don't dismiss any of these signs in your middle-aged to older dog, and always  follow the advice of your vet regarding running blood work to rule out something like this.