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Addison’s Disease in Dogs: Causes, Signs, Diagnosis, and Treatment

Addison’s disease in dogs is known as primary hypoadrenocorticism, which is caused by the destruction or loss of the adrenal cortices. The disease occurs when the adrenal glands unable to produce hormones. The hormones are essential to control salt, sugar, and water balance in the body. Addison’s disease occurs more frequently in the dog than is recognized, but it is much less common than hyperadrenocorticism or Cushing’s disease.

Important Information on Addison’s Disease in Dogs

Hypoadrenocorticism emerges to be a disease of the young and middle-aged dog with an age range of three months to nine years and a median age of 4-5. Approximately 70% of reported cases are female. The disease is rare in the cat, but the signs, diagnosis, and treatment of similar in dogs and cats.

Information on Addison's Disease in Dogs

Causes of Hypoadrenocorticism in Dogs

The most common causes of Addison’s disease are as follows:

  • Idiopathic adrenocortical insufficiency. This is the commonest cause in dogs and is thought to result from immune-mediated destruction of the adrenal cortex. 
  • Mitotane-induced adrenocortical necrosis. Although mitotane usually allows the zona glomerulosa and therefore mineralocorticoid secretion, cases of complete adrenocortical failure can occasionally occur. 

Causes of Hypoadrenocorticism in Dogs

  • Bilateral adrenalectomy, hemorrhage, or infarction of the adrenal cortex or neoplastic or mycotic entanglement of the adrenal gland can also start adrenal insufficiency, but these are rare causes.

What are the Symptoms of Addison’s Disease in Dogs?

The progression of adrenocortical deficiency may be acute or chronic. The chronic form is far more common than the acute disease in the dog. The symptoms of Addison’s disease include:

  • The hypovolemic shock (the adrenocortical crisis).
  • Weak pulse.
  • Profound bradycardia.
  • Abdominal pain.
  • Vomiting.
  • Low body temperature.

Australian Terrier Dog Breed

  • Hypoglycemia.
  • Hyperpigmentation of the skin.
  • Diarrhea.
  • Dehydration.
  • Hypothermia.
  • Anorexia.
  • Lethargy.
  • Depression.
  • Weakness.
  • Weak femoral pulses.
  • Weight loss.
  • Bloody stools.
  • Alopecia (hair loss).
  • Increased thirst.
  • Increased urination.
  • Shaking.
  • Irregular heart rate.
  • In a few cases, severe GI hemorrhage can occur, resulting in profound anemia.

Location of Adrenal Glands in Dogs

Diagnosing Addison’s Disease in Dogs

Diagnosis is made on your dog’s medical history, laboratory findings, electrocardiographic findings, radiographic findings, and endocrine testing. Your veterinarian recommended various types of tests, and the definitive test for Addison’s disease is the ACTH stimulation test. 

The most consistent laboratory data in hypoadrenocorticism are prerenal azotemia, hyponatremia, and hyperkalemia. Blood urea and serum creatinine are increased due to reduced renal perfusion and decreased glomerular filtration rate. Reduced renal perfusion results from hypovolemia, reduced cardiac output, and hypotension, resulting from chronic fluid loss through the kidneys, acute fluid through vomiting and diarrhea, and inadequate fluid intake.

Diagnosis of Addison's Disease in Dogs

Hyperkalemia impairs cardiac conduction, which ECG can assess. Although the ECG changes do not interact directly with serum potassium levels, the following guidelines have proved helpful. Changes in the ECG can also be used for monitoring the patient during treatment.

Dogs with Addison’s disease may show radiographic signs of hypovolemia which include microcardia, decreased size of pulmonary vessels, and atrophied size of the posterior vena cava. The changes are not definite and only represent changes associated with hypovolemia and dehydration, irrespective of the cause. A few dogs with Addison’s disease develop esophageal dilatation due to generalized muscle weakness, which can be seen on thoracic radiographs. 

Cushing Disease in Dogs

The ACTH stimulation test is usually used to confirm the presence of hypoadrenocorticism. Plasma ACTH concentrations are required to differentiate primary and secondary Addison’s disease. Plasma ACTH concentrations are low in secondary hypoadrenocorticism and markedly raised in primary hypoadrenocorticism.

Differential Diagnosis of Addison’s Disease

The disease confused with the following:

  • Chronic renal insufficiency.
  • Primary neuromuscular disorders.
  • Diseases of dogs that cause weight loss.
  • Weakness.
  • Anorexia.
  • Vomiting.
  • Diarrhea.
  • Acute pancreatitis.
  • Toxin ingestion.

How is Addison’s Disease in Dogs Treated?

Your veterinarian will prescribe the disease treatment and decide which therapy is best for your dogs. Aggressive intravenous fluid therapy using normal saline and glucocorticoid therapy can be used in the acute crisis to treat hyperkalemia, which is life-threatening for your pets. Once the animal has improved with saline and glucocorticoids, maintenance therapy with mineralocorticoids can be instigated. Dexamethasone sodium phosphate, hydrocortisone sodium succinate, prednisolone sodium succinate are used to treat Addison’s disease in dogs.

Treatment of Hypoadrenocorticism in Dogs Lethargic Dog

Fludrocortisone acetate is an oral synthetic adrenocortical steroid with mineralocorticoid effects and is the treatment of choice for maintenance therapy for your dog. Desoxycorticosterone pivalate (DOCP), a long-acting ester of desoxycorticosterone acetate, can be used as an alternative. It is injected every 3-4 weeks, basing on the patient. It replaces the missing mineralocorticoid aldosterone and is often supplemented by an oral glucocorticoid. 

Prognosis of Hypoadrenocorticism in Dogs

The prognosis for Addison’s disease is generally excellent. Your vets will provide you the adequate information on the long-term prognosis for your dog. The disease recovered after proper treatment. I have provided almost all possible information about the disease. You will be benefitted from this article. 

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