Hypoadrenocorticism (Addison’s Disease) in Dogs

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Overview of Canine Hypoadrenocorticism (Addison’s Disease) 

Hypoadrenocorticism, also called Addison’s disease, is an endocrine disorder that results from a deficient production of adrenal gland hormones that can occur in dogs. There are two adrenal glands in the abdomen that lie just in front of the kidneys.

The most common cause of Addison’s disease in the dog is destruction of the adrenal gland tissue by the animal’s immune system. Infrequently, certain infections, medications, cancer or diseases of the pituitary gland may also cause Addison’s disease.

Addison’s disease may also be caused by the abrupt discontinuation of steroid medication. Dogs that have been on long-term steroids should be slowly weaned off such drugs. Abruptly stopping the medication can result in an Addisonian crisis.

Addison’s disease is an uncommon disorder in dogs and is extremely rare in cats. It is thought to be familial and inherited in Leonbergers, standard poodles, and Nova Scotia duck tolling retrievers. Certain other breeds may also be predisposed, such as the Airedale, bearded collie, German shepherd dog, German shorthair pointer, Great Dane, St. Bernard, English springer spaniel, West Highland white terrier, wheaten terrier, and Portuguese water dog.

Hypoadrenocorticism most often affects young to middle-aged dogs. About 70 percent of affected dogs are female. Neutered male dogs are more likely to develop hypoadrenocorticism than intact male dogs.

In hypoadrenocorticism there is usually a deficiency of two different groups of hormones, the glucocorticoids and the mineralocorticoids. The primary glucocorticoid hormone is cortisol, and it is responsible for combating stress, helping to maintain blood sugar. The major mineralocorticoid is aldosterone. Aldosterone regulates the water, sodium, potassium, and chloride concentrations in the body. Most naturally occurring forms of Addison’s disease affects both hormones. Addison’s disease secondary to the abrupt withdrawal of steroid medications affects only the level of circulating cortisol.

What to Watch For

The clinical signs seen with Addison’s disease are somewhat variable. They may be mild and very vague initially. With an acute crisis, the signs are more pronounced and profound. Clinical signs include:

  • Lethargy, weakness
  • Poor appetite
  • Vomiting
  • Weight loss
  • Depression
  • Dehydration
  • Diarrhea
  • Excessive thirst and water intake (polydipsia)
  • Vomiting
  • Diarrhea
  • Low body temperature, shaking, collapse, low heart rate
  • Diagnosis of Hypoadrenocorticism (Addison’s Disease) in Dogs

    Because hypoadrenocorticism can mimic many other diseases, diagnostic tests are needed to confirm the presence of Addison’s disease, and to exclude other diseases that cause similar signs. These tests may include:

  • Complete medical history and physical examination
  • A complete blood count (CBC), blood biochemistry profile and urinalysis
  • An ACTH stimulation test (the diagnostic test of choice)
  • Chest and abdominal radiographs (X-rays) and possible abdominal ultrasound, depending on the clinical symptoms
  • Treatment of Hypoadrenocorticism (Addison’s Disease) in Dogs

    Treatment depends on whether the onset of illness is acute with severe symptoms, or whether more mild, chronic signs are present. For acute disease (an Addisonian crisis) treatment may include:

  • Intravenous fluid therapy
  • Electrolyte and acid-base monitoring
  • Corticosteroid and mineralocorticoid replacement therapy

    Treatment for chronic disease may include:

  • Corticosteroid and mineralocorticoid replacement therapy
  • Daily salt supplementation
  • Home Care

    At home, administer any prescribed medication precisely as directed by your veterinarian. Observe the dog’s activity level, appetite and water intake. Also, report any occurrence of vomiting, diarrhea, weakness, and change in appetite to your veterinarian immediately. Regularly scheduled veterinary visits are needed to monitor the disease and response to treatment. Such exams often involve various tests to monitor the levels of sodium and potassium in the blood.

    Some dogs have different medication needs during times of stress such as travel, surgery, or hospitalization. Be sure to discuss this with your veterinarian if you anticipate times of stress in the future.

    Preventative Care

    There is no preventative measure for the naturally occurring forms of this disease. If your dog is receiving steroid medication, do not stop the medication abruptly. By doing so, an Addisonian crisis can occur. This is the only form of Addison’s disease that is preventable.

    In-depth Information on Hypoadrenocorticism (Addison’s Disease) in Dogs

    Hypoadrenocorticism is a relatively uncommon disease, but it is highly treatable. Nevertheless, without proper veterinary care, the condition can be fatal. Because the history, clinical signs, and presentation of dogs with hypoadrenocorticism are so variable, there are other illnesses that must initially be considered when establishing a definitive diagnosis. These illnesses may include:

  • Gastrointestinal (GI) foreign bodies that cause vomiting, diarrhea, and weakness
  • Infections of the gastrointestinal tract with bacteria (Salmonella, Campylobactor, Clostridia), viruses (parvovirus, coronavirus), fungi (histoplasmosis), or parasites (whipworms)
  • Neoplasia (cancer) of the gastrointestinal tract, such as lymphosarcoma and adenocarcinoma
  • Inflammatory bowel disease (IBD), a syndrome of chronic intestinal inflammation
  • Kidney diseases, such as acute kidney failure and pyelonephritis (infection of the kidney)
  • Pancreatitis, an inflammation of the pancreas that causes severe vomiting and diarrhea
  • Urinary blockage resulting in hyperkalemia (high blood potassium) and azotemia (abnormal kidney function test)
  • Diseases causing hypercalcemia (high blood calcium levels), such as cancer and parathyroid gland diseases
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