Cushing’s disease is caused by the adrenal gland in the dog’s abdomen next to the kidneys. The adrenal gland produces too much cortisol, which affects the other parts of the body. Cortisol controls stress in the body and impacts the kidneys, nervous system, skeletal system, immune system, cardiovascular system, metabolism and blood sugar levels. Cushing’s disease can come in two forms: adrenal-dependent and pituitary-dependent.
Cushing’s disease is primarily caused by tumors. Dogs that are spayed or neutered seem to have a slight increase of risk. Breeds of dog such as golden retrievers, Labrador retrievers, boxers, dachshunds, poodles, beagles and terriers have a higher risk of contracting this disease.
Because Cushing’s disease primarily affects older dogs, many of the symptoms of this disease are mistaken for old age. The symptoms of Cushing’s disease include a potbellied appearance, hair loss, weight gain, loss of muscle mass and changes to the fur and skin. Increases in appetite, water intake and urination are also common. In rare cases, Cushing’s disease may cause breathing problems, panting, stiffness and weakness. It can also lead to diabetes and seizures.
Cushing’s disease is often difficult to diagnose; so various tests will need to be performed. Routine blood work and a urine analysis will be done first to rule out any other diseases. Lab tests will check the white blood cell count and liver enzymes, which could point to a diagnosis. Ultrasounds and X-rays will show evidence of tumors or enlarged organs caused by the disease.
In this case, treatment is used to improve the quality of life. Determining the right treatment for your dog can be difficult. Because Cushing’s disease primarily occurs in old age, many dogs have co-occurring diseases. It some cases, it is better to just let the dog remain with the disease as is than try to fight it.
However, younger and healthy dogs may good candidates for treatment. Chemotherapy is often used. Radiation can also be used to shrink the tumor, but it must be done repeatedly, which can be very expensive.
If the disease is caused by a tumor in the adrenal gland, then the best approach is to surgically remove the tumor. Dog who undergo surgery have a very good prognosis because the removal of the tumor cures the disease in many cases. However, half of all adrenal tumors are malignant and have spread. On top of that, the dog is usually elderly, making surgery a difficult decision for many dog owners. Most choose non-surgical options.
Pituitary tumors cannot be removed. They are often small and do not grow quickly. They cause little harm, and if they do cause any symptoms, treatment is used to alleviate those symptoms.
Most cases of Cushing’s disease are treated by oral medications such as Lysodren and Ketaconazole. Anipryl is sometimes used, but it is controversial, as its main use is for senile dogs. It balances brain chemicals, which can help dogs with pituitary-dependent Cushing’s disease.
If properly treated, the symptoms of Cushing’s disease can disappear within six months. If left untreated, the disease can progress and cause infections, diabetes, seizures, hypothyroidism and heart, kidney and liver failure.