Types

• Hypothyroid disease occurs when your dog's thyroid gland, located in the neck just behind the larynx, atrophies and stops releasing the thyroid hormone responsible for the control of metabolic function.
  
  Diabetes mellitus results when your pet's pancreas stops manufacturing the insulin hormone, which facilitates the entry of glucose into the cells for the creation of energy.
  
  The decreased production of glucocorticoids and mineralocorticoids by the adrenal glands results in Addison's Disease (hypoadrenocorticism), a relatively rare, but life-threatening disease that affects the animal's liver function and can interfere with your dog's immune system, says Dr. Alleice Summers in her book, "Common Disease of Companion Animals." The over-production of the dog's normal levels of the steroid cortisol, called hyperadrenocorticism, results in Cushing's syndrome.
  
  

Symptoms

• Dogs with hypothyroid disease gain weight without an increase in their normal diet, develop chronic skin infections with a poor hair coat, and become weak and lethargic. They can become anemic and intolerant of the cold.
  
  If your dog drinks an excessive amount of water, and urinates and defecates constantly, it might be diagnosed with diabetes. Diabetic dogs become dehydrated easily, show signs of depression and weakness and can suddenly develop cataracts.
  
  Addison's Disease in your dog can display symptoms similar to those of diabetes, with signs of depression, lethargy, weight loss, vomiting, excessive drinking and urination coming and going over a period of time. Veterinarians call Addison's "The Great Pretender" because its symptoms, including decreased pulse and low body temperature, mimic so many other diseases, say the vets at the Veterinary Housecall Service of Rochester in the New York.
  
  Canines with Cushing's syndrome experience excessive eating, drinking and urination, and often become obese with an enlarged torso. They will lose their hair due to extreme itching and scratching, and develop skin and urinary infections. Cushing's dogs pant more than usual and show signs of muscle weakness.
  
  

Treatment

• The veterinary treatment of canine endocrine disorders depends upon the diagnosis.
  
  Dogs with hypothyroidism require supplementation with a synthetic, thyroid replacement for life, while animals with diabetes mellitus need lifelong insulin therapy and a specialized diet to control their disease. Veterinarians typically place the Addison's dog on oral steroids for several weeks, tapering the dose gradually until clinical signs begin to abate and blood levels normalize. At that point, a twice-daily dose of steroids is recommended with periodic veterinary testing of electrolytes and kidney function, states Dr. Summers. Dogs with Cushing's receive a drug that kills the part of the adrenal gland that is producing the cortisol. This lifelong medication may be supplemented with surgical removal of one or both adrenal glands.
  
  

Considerations

• A middle-aged or older female dog becomes the typical endocrine patient, according to Dr. Summers. Schnauzers, dachshunds, Doberman pinschers, Irish setters or golden retrievers show a predisposition for hypothyroidism, while those same breeds, plus poodles, keeshonds, cocker spaniels and beagles, also develop diabetes in large numbers. Addison's and Cushing's, also seen predominantly in older females, show no breed delineation.
  
  

Prognosis

• Most dogs diagnosed with endocrine diseases respond well to the prescribed therapy and live long, productive lives, says the Veterinary Housecall Service website. Veterinarians typically give a good to excellent prognosis to affected canines.