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Addison's Disease in Dogs

Addison’s disease causes vague signs of illness in dogs.

Addison's disease in dogs is also known as hypoadrenocorticism. It is a serious condition that can quickly be life-threatening.

What Causes Canine Addison's Disease?

The adrenal glands, which are located near the kidneys, produce hormones that control numerous body functions. Cortisol, which is the hormone that responds to stress, and aldosterone, which controls sodium and potassium levels are two important substances made by the adrenal glands.

Addison's disease is when the adrenal glands are not producing enough of these critical hormones. It is often diagnosed in young dogs, around 2-6 years of age, though younger and older dogs can also be affected.

Addison's disease can occur for three main reasons:

  • Damage to the adrenal gland may be caused by the body itself during immune-mediated disease. The damaged tissue is unable to produce cortisol and aldosterone. Damage to the adrenal glands also occurs during treatment for Cushing's syndrome, and if too much damage is done, Addison's can result.
  • A tumor in the pituitary gland in the brain can cause Addison's disease by interfering with its ability to send the proper signals to the adrenal glands to stimulate hormone production.
  • Iatrogenic Addison's disease can occur when a dog is on high doses of steroid medication or is on such medicine for a long period of time, and then it is suddenly stopped. This can be avoided by slowly tapering a dog off of steroids rather than stopping them abruptly.

What Are the Signs of Addison's Disease in Dogs?

The signs of canine Addison's are often quite vague. They include:

  • Weakness
  • Lethargy
  • Vomiting
  • Diarrhea
  • Increased thirst and urination
  • Weight loss
  • Shaking

Signs come and go and often appear when the dog is stressed because stress is usually met with increased cortisol production in the adrenal glands.

An Addisonian crisis occurs when the disease causes shock. Crisis signs are severe and life-threatening. Serious vomiting, diarrhea, and collapse are present.

Diagnosis of Canine Addison's Disease

It can be difficult to determine that Addison's disease is the cause of a dog's clinical signs because they are often vague and intermittent.

Physical exam of a dog suffering from Addison's may reveal a slower than normal heartbeat, weakness, and dehydration. If electrolyte levels are tested, there will often be a low sodium and high potassium level, leading to a low sodium: potassium (Na: K) ratio.

If Addison's disease is suspected after the history and physical exam are completed, an ACTH stimulation test is done. A dog's cortisol level is tested, then exogenous, synthetic ACTH is injected. ACTH stimulates the adrenal glands to produce cortisol. A second cortisol level is tested to determine whether the adrenal glands are responding to ACTH properly.

Treatment of Canine Addison's Disease

Dogs in an Addisonian crisis need emergency care. They will be hospitalized for fluids, steroids, and any other necessary medications.

Long-term treatment of canine Addison's disease is done either with an injection given at home around every 25 days (DOCP, or Percorten) or with daily oral medication (Florinef). Most dogs also require oral steroids daily.

Dogs being treated for Addison's disease need to be monitored closely at home and periodically at the veterinary office. Even dogs that do not routinely take steroids will require them during stressful times such as when they are boarding, moving, etc.

Prognosis for Dogs with Addison's Disease

Dogs with Addison's usually do well once they are diagnosed and stabilized with medication.

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