Q: My dog Roadie is 14 y ears old and has had a somewhat rough life. We found him on the roadside where he had been dumped by some uncaring person, looking bewildered and lost. We took him in to our veterinarian and had him checked over, neutered, all his shots, etc., and he has been a loving companion ever since. He has an autoimmune disorder that has affected his skin. Lately he has been drinking excessive amounts of water and accidentally urinates in the house. He has never had accidents in the house before.
We had his urine checked and it was very normal except for being very watery and not at all concentrated. His blood work said he was not diabetic and that his kidneys were working fine. He had some liver enzymes that were elevated and with his dilute urine and somewhat pot-belliedness, our veterinarian wants to test him for Cushing’s disease. What is this disorder, can it be treated and will it help his quality of life enough at 14 that we should proceed?
A: Cushing’s disease is one of the most common endocrine disorders occurring in dogs. It happens in humans as well but is about 100 times more common in dogs. It occurs more commonly in middle-aged to older dogs and very rarely in cats.
The disease itself is hyperadrenocorticism or an excessive production of cortisol by the adrenal gland(s)(. Cortisol is known as a stress hormone because when the body has a stressful event, cortisol secretion increases and helps to provide greater amounts of glucose for the body to use. The body cannot function without cortisol, but too much is not good either.
Excessive cortisol results in increased water consumption, thus increased urine production. It also can suppress the immune system, cause muscle weakness and create a resistance to insulin resulting in secondary diabetes.
Diagnosing it can be challenging and it frequently takes two or three blood tests to do the diagnosis. Occasionally when there are several signs such as excess water consumption, muscle weakness, increased food intake, pot-bellied appearance and frequent skin problems as well as elevated liver enzymes, diabetes and low potassium level, retesting should be done in a couple of months.
Cushing’s disease can involve the pituitary gland in about 15 percent of cases, or the adrenal gland(s) in about 85 percent of cases. A blood test and X-rays and/or ultrasound can be helpful in differentiating the source of the disease. Pituitary-dependent patients usually respond well to treatment and can have three to four years of quality life. Surgery to remove the pituitary or adrenal gland or tumor on the adrenal can be done, but replacement medications still must be given.
The adrenal disease is more challenging because it is usually due to a malignant tumor in the adrenal gland(s). Surgery may be an option or a medication can be given that blocks the synthesis of cortisol in the adrenal gland. The downside of medication is that it currently costs about $7 a pill to treat and is prescribed per the weight of the animal. Initially there is a daily loading dose for 7-10 days, and then a retest to be sure the dose is correct. The medication is then given at this dose two days a week for life. Retesting may be required if some of the initial signs reappear as the tumor/growth changes over time. So, like diabetes, treating this disease can be time-consuming and expensive. It requires a lot of love, patience and dedication for your best friend, but it is doable.
DR. M. MARGARET KING, a longtime Edmond veterinarian, is a guest columnist. If you have any questions for her, email them to email@example.com.