Is Stress Causing Your Dog's Cushing’s Disease?
When your dog is stressed, the fight or flight hormone - cortisol - is secreted. Constant stress can ramp up the body's cortisol production and cause your dog to develop Cushing's disease. Dr. Cathy Alinovi of HealthyPAWsibilities has some answers to the most frequently asked questions about this dangerous disease.
Question 1: What is Cushing's disease (hyperadrenocorticism)?
Dr. Cathy: Cushing’s is over-production of cortisol by the adrenal gland. The adrenal gland is a tiny little gland that sits on top of the kidneys. The adrenal gland, while small, has several functions. It produces hormones for salt balance in the body, sex hormones, and most importantly in Cushing’s disease, cortisol.
“Hyper” means over or too much, “adreno” means the adrenal gland, “corticism” means production of cortisol.
How many types of Cushing's Disease?
- Iatrogenic (caused by medication)
- Pituitary-dependent (a tumor of the pituitary gland)
- Adrenal dependent (tumor on the adrenal gland) Cushing’s
Q2: What causes it?
Dr. Cathy: Cushing’s disease – pituitary dependent (PDH), adrenal dependent (ADH) and iatrogenic – all result from too much cortisol in the body.
In pituitary-dependent Cushing’s, there is a tumor in the pituitary gland, which is a tiny little gland at the base of the brain that makes many hormones to tell body organs how to perform. The pituitary tumor causes overproduction of the hormone that tells the adrenal gland how to function.
In ADH, there is a tumor on the adrenal gland itself, causing the gland to over-function.
In iatrogenic Cushing’s, humans cause the disease by giving too many steroids to their dog, usually as treatments for allergies or cancer.
Q3: What are the common symptoms?
Dr. Cathy: Cortisol is a stress hormone. When we are stressed, we eat more, we urinate more, and we drink more. The same is true for our dogs; they get hungrier, so they gain weight, they urinate more, which makes them thirsty, and so they drink more. Due to the weight gain, they get round in the belly. Other common symptoms are thin skin, hair loss or thinning coat, muscle wasting, and enlarged liver due to excess sugar storage in the liver.
Breeds Predisposed to Cushing's Disease
Q4: Are there uncommon signs pet owners should know?
Dr. Cathy: Low thyroid function can occur with Cushing’s since the pituitary gland also controls thyroid function and the cortisol will suppress thyroid function. There can be diabetes along with the Cushing’s disease due to the effects of cortisol on the kidneys and kidney involvement in insulin production.
Excessive cortisol also leads to:
- Hardening of the skin
- Black heads (comedones)
- Frequent bladder infections with a predisposition to bladder stones
- Panting from weak chest muscles
- Brain malfunction from growing brain (pituitary) tumor
Other unusual signs are tumors around the rectum in neutered dogs (tumors in that region are common in unaltered dogs, but not in altered dogs).
Q 5: Are there side effects from prescription medicines that mimic CD?
Dr. Cathy: When steroids are given on a daily basis and/or at too high a dose, it can cause iatrogenic Cushing’s, as discussed above. These steroids are given for dogs with extreme allergies or as cancer therapy. Steroids (prednisone) produce a cortisol-like effect on the body and all the same symptoms as Cushing’s disease may develop.
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Q6: What is the diagnostic procedure?
Dr. Cathy: A good history will quickly rule in or out iatrogenic Cushing’s because if your dog is not taking steroids, it won’t develop iatrogenic disease.
If some of the liver enzymes are elevated when screening blood work is performed, then more testing is required.
Measuring cortisol levels in the blood, and how the levels change in response to giving cortisol is how the test is done to determine if PDH or ADH exist. At that point, an ultrasound of the abdomen will show one enlarged adrenal gland in the case of ADH to determine the difference between the two. More recently, some veterinarians use a newer test to measure cortisol in the first morning urine. This is an inexpensive test to rule in or out the disease.
Cushing's Disease in Dogs
Q7: What are the treatments for Cushing's disease?
Dr. Cathy: Iatrogenic is easily treated by slowly decreasing the dosage of prednisone the dog is taking. ADH is a little bit more difficult; if the tumor is only in one adrenal gland, it can be surgically removed.
PDH is the hardest to treat for several reasons. First, the pituitary gland is hidden deep in the skull so it is hard to access. Secondly, the pituitary is essential for life; removal of the gland will affect all body functions, not just the adrenal gland. Therefore, medication that suppresses adrenal gland function is given to slow the signs of Cushing’s disease.
Q8: What is Western medicine's treatment for Cushing’s?
Dr. Cathy: Three drugs treat Cushing’s:
Lysodren works by destroying the adrenal gland slowly so it cannot make too much cortisol. Trilostane inhibits steroid production by the adrenal gland. Selegiline works in the pituitary gland by decreasing hormone production to the adrenal gland. Regardless of the medication, they are all quite expensive and have serious side effects.
Q9: What alternative medicine approaches are there?
Dr. Cathy: Herbal medicine looks at the whole picture of the Cushingoid dog such as how advanced is the disease, is the dog hot or cold, does the dog drink a lot, are pulses weak on the right or the left, etc. Classical Chinese herbal formulas include:
- Mai Men Dong
- Xia Xiao Feng
- Jin Gui Shen Qi Wan
Food therapy includes switching to a grain-free diet as sugars and grains will worsen the effects of cortisol on the body. The food should also be low in carbohydrates as the body can turn carbs into sugars as well. Because dry dog food is full of either grain or carbohydrates or both, the dog should eat real food – cooked or raw.
Nutraceuticals and homeopathics can also help to stabilize a Cushing’s patient.
Q10: What else should dog owners know about canine Cushing’s disease?
Dr. Cathy: Cushing’s disease doesn’t just happen overnight; it takes months or years to develop.
Early signs of the disease are pot-bellied dogs that don’t lose weight. These dogs usually eat lower quality dry dog food their whole lives.
Screening blood work early in the disease will reveal only elevation of one liver enzyme – AlkPhos or Alkaline Phosphatase – an enzyme that goes up when there is too much cortisol in the body. Dogs that have stress have elevated cortisol, just like humans. If the condition is allowed to continue, Cushing’s disease can develop.
© 2014 Donna Cosmato
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