Cushings Disease in Dogs

Cushings disease in dogs, cushing’s syndrome, or sometimes referred to as hyperadrenocorticism is a dog disease or disorder of the endocrine system associated with abnormally high levels of corticosteroids, a hormone which is produced by the adrenal glands that are located near the kidneys. A majority of the cases of cushing syndrome in dogs are seen at 5 years old and older; however, younger dogs have been known to be affected by this condition as well. Although this hormonal problem has been observed to occur in any breed of dog, the highest incidence has been observed in Poodles, Dachshunds, Boston Terriers, and Boxers. Causes of cushing’s disease in dogs can be naturally-occurring or as a result of prolonged exposure to exceptionally high levels of administered corticosteroids. The latter is also called Iatrogenic Cushing’s and is relatively easier to reverse compared to other dog diseases which are naturally-occurring like cushing’s disease. There are two predisposing factors which have been pointed to as culprits of hyperadrenocoriticism. 1. An adrenal gland tumor that also produces adrenal hormones 2. A tumor in the pituitary gland that causes overproduction of the Adrenocorticotrophic Hormone ( ACTH), a pituitary hormone that can stimulate the adrenal glands to produce adrenal hormones. More than 80% of cases of cushing in dogs are caused by a pituitary tumor.  Since the corticosteroid hormone is responsible for many physiological functions of major organs, a dog suffering from cushing’s disease often manifests a variety of clinical signs. The most important and common signs include the following:

  • Polydipsia – increased drinking
  • Polyuria – increased urination
  • Hair loss particularly on the dog’s body. Hairs on the head and legs are spared
  • Pot-bellied appearance
  • Panting
  • Increased appetite
  • High blood pressure
  • Increased susceptibility to skin infections
  • Weakening of the skeletal muscles which is more pronounced in the hind legs resulting in abnormal gait
  • Increased defecation
  • Thinning and increased sensitivity of the skin
  • Circling movements

Dogs suffering from cushing’s disease may develop serious complications including congestive heart failure, blood clots in the circulatory system, increased susceptibility to infections, seizures and Diabetes mellitus. Diagnosis of Canine Cushing Disease aside from the clinical signs, your veterinarian will have to conduct various blood tests and specific diagnostic tests to arrive at an accurate diagnosis.

  • CT scans help detect the presence of tumors of the pituitary gland and adrenal glands
  • Magnetic Resonance Imaging (MRI) can help visualize even the smallest tumors of the pituitary and adrenal glands
  • Ultrasound can visualize the symmetry and measure the size of the adrenal glands
  • Low-dose Dexamethasone Test helps establish the presence of cushing’s disease
  • High-dose Dexamethasone Suppression Test helps differentiate between tumors of the adrenal gland and pituitary gland
  • ACTH-response test
  • Urine Cortisol/Creatinine Ratios

Treatment of cushing’s disease in dogs

The presence of a pituitary tumor that causes cushing’s syndrome in dogs can only be treated symptomatically. There is no cure for cushing’s disease and every cases has a guarded prognosis. Even with medical treatment, the average lifespan of dogs diagnosed with the condition is around two years. Mitotane can be used to selectively suppress production of adrenal hormones but the process requires close veterinary monitoring. In some cases, tumors of the adrenal gland may be surgically removed. Some cases respond favorably to radiation therapy however the procedure is very expensive and there are only a few clinics that can undertake the treatment regimen. On the other hand, Iatrogenic Cushing’s Disease in dogs can often be reversed if the causative medication is tapered or altogether stopped.

Photo Source: Cute Poodle

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