Addison’s Disease in Dogs

Hypoadrenocorticism in Dogs

 

Mineralocorticoids and glucocorticoids are hormones normally produced by the adrenal glands, which are located near the kidneys. Both of these hormones are critical to the healthy functioning of the body, and an abnormal increase or decrease of either of these hormones can lead to serious health problems if not addressed in time. Hypoadrenocorticism is characterized by a deficient production of glucocorticoids and/or mineralocorticoids. Deficient production of both these hormones can cause a number of symptoms like weakness, dehydration, low blood pressure, depression, heart toxicity, vomiting, blood in feces, and weight loss.

 

This disease is relatively rare in dogs, but when it does occur it tends to be seen most often in young to middle-aged dogs, female dogs, and may be familial in Bearded Collies, Standard Poodles, Portuguese water dogs, West Highland white terriers, rottweilers, and wheaten terriers.

 

Symptoms and Types

 

Symptoms will vary depending on the duration of the problem. Life-threatening symptoms are usually observed in acute episodes of this disease. The following symptoms are commonly observed in dogs:

 

• Lethargy
• Lack of appetite (anorexia)
• Vomiting
• Weight loss
• Diarrhea
• Shaking
• Increased frequency of urination (polyuria)
• Increased thirst (polydipsia)
• Depression
• Dehydration
• Weak pulse
• Collapse
• Low temperature
• Blood in feces
• Hair loss (alopecia)
• Painful abdomen

 

Causes

 

• Adrenocorticotropic hormone (ACTH) deficiency
• Metastatic tumors
• Long term glucocorticoid withdrawal

 

Diagnosis

 

You will need to give your veterinarian a thorough history of your dog's health and onset of symptoms. Your veterinarian will perform a thorough physical exam on your dog, including routine laboratory tests, a complete blood count, biochemistry profile, and urinalysis. The complete blood count may reveal anemia, an abnormally high number of eosinophils (a type of white blood cells that readily stains with eosin dye), and an increased number of lymphocytes (also a type of white blood cell) called (lymphocytosis).

 

 

Serum biochemistry testing may reveal an abnormally higher level of potassium, and an accumulation in the blood of urea - nitrogenous waste products that are usually excreted out of the body through the urine (azotemia). Other findings include lower levels of sodium (hyponatremia) and chloride (hypochloremia), increased levels of calcium (hypercalcemia), increased liver enzymes, including ALT and AST, and low blood sugar (hypoglycemia). The urinalysis may reveal a low concentration of urine. The definitive test for diagnosing this condition is by detecting the levels of cortisol in the body. Normally the adrenocorticotropic hormone (ACTH) is produced by the pituitary gland, which then stimulates the adrenal glands to release their hormones. ACTH can be injected into the body to test the normal response functions of the adrenal glands. If your dog's adrenal glands do not show an increase in the release of hormones after being given ACTH, then the diagnosis of hypoadrenocorticism will be confirmed. Visual diagnostic procedures, like X-ray and ultrasound, may reveal smaller than normal adrenal glands.

 

Treatment

 

A sudden and severe (acute) episode of hypoadrenocorticism is a medical emergency requiring immediate hospitalization and intensive therapy. The treatment for this disease depends on the type and severity of symptoms. Patients with low bodily fluids are given intravenous fluids to replace the deficient fluid levels, but the cornerstone of therapy is to supplementally replace the deficient hormones. Dogs that have been diagnosed with this condition need to be treated with hormone injections for the rest of their lives.

 

Living and Management

 

In case of an acute episode of hypoadrenocorticism, your dog will need immediate treatment due to life-threatening symptoms. After the initial recovery, your veterinarian will calculate the dose that will balance your dog's hormone deficiency. The dose of these hormones may need to be increased occasionally, especially during periods of stress like travel, hospitalization, and surgery. Do not alter the brand or dose of hormone that has been prescribed without first consulting your veterinarian.

 

After the initial hormone replacement, you will need to visit your veterinarian at weekly intervals for at least the first four weeks. Your veterinarian will measure your dog's hormones during therapy and will modify the doses accordingly. Hormone injections are usually required at monthly intervals, and in some patients they are required every three weeks. Electrolyte levels will also be checked regularly due to the significant alternations in electrolytes that are typically seen with this disease. Good owner compliance is required for the life of the patient in order to benefit from treatment. However, with regular treatment, most patients do well and have a good prognosis.