I wrote this article because Cushing’s disease in dogs is often over-diagnosed.
Over-diagnosed is a euphemism for “your dog never had it in the first place.” And that’s a problem.
My goal? To give you the facts on how the testing procedure for Cushing’s disease works and what exactly vets are looking for. This should help save unnecessary expenses and worry.
So it’s important that we fully understand this disease.
What Is Cushing’s Disease In Dogs?
Cushing’s disease is an endocrine disorder of middle aged and older dogs. It’s the result of the overproduction of cortisone by the adrenal glands. These are tiny glands the size of a pea located on each kidney.
Normally, your dog’s pituitary responds to stress by producing something called ACTH. This stimulates his adrenals to produce more cortisol/cortisone. In Cushing’s disease, really high levels of cortisone hormone are produced continually.
Cushing’s disease results from three possible situations:
A dog will have a microscopic benign tumor of the pituitary gland. This tumor overproduces ACTH. This stimulates the adrenal glands to produce too much cortisone. About 85% of Cushing’s cases in dogs are due to a pituitary tumor.
Cushing’s disease is caused by a tumor in the adrenal gland that’s busy secreting too much cortisol. This is the case in about 15% of dogs.
The third scenario occurs when a veterinarian prescribes excessive steroids as a medication. With NSAIDs (non-steroidal anti-inflammatory drugs), the incidence of this is waning.
And when it comes to Cushing’s disease in dogs, there are two problems to contend with:
Tests that determine if your dog has Cushing’s disease are expensive and can be unreliable.
One commonly used drug to treat Cushing’s, Lysodren, will destroy your dog’s adrenal glands. This just compounds the problem created by an incorrect diagnosis.
Let’s start at the very beginning, using a typical experience that might very well happen to you and your dog. Let’s name your imaginary dog Spot. Spot is over six years old and you take him in for his annual examination. He gets his annual Wellness Profile: a blood test. Spot has none of the symptoms of Cushing’s disease. He’s not drinking a lot or urinating a lot. He doesn’t have a sagging, bloated, pot-bellied appearance or excess panting. He’s not extra hungry or stealing food, hasn’t gained weight and he’s not weak on his hind legs, having no loss of muscle mass. His coat is beautiful and thick with no thinning of his fur and he has no areas of pigmented skin. He never gets an infection.
Spot has one thing and one thing only: elevated alkaline phosphatase. This is a liver enzyme and if it’s 2 to 3 times the normal range, Cushing’s disease is often pegged as the likely problem.
But any disorder causing endogenous stress can cause high alkaline phosphatase in dogs …