A Dog's Life

Diagnosis

Symptoms of Addison's disease in canines can include vomiting, diarrhea, lethargy, lack of appetite, tremors or shaking, muscle weakness, low body temperature, collapse, low heart rate, and pain in the hind quarters.[9][22] Hypoglycemia can also be present, and initially may be confused with seizure disorders, insulin-secreting pancreatic tumor (insulinoma), food poisoning, parvovirus enteritis, gastric volvulus, spinal or joint problems, earning Addison's disease the nicknames of "the Great Mimic" and "the Great Imitator".[7][14] It is possible not to see any signs of the disease until 90% of the adrenal cortex is no longer functioning.[23]

Signs that a dog may have Addison's disease include elevated levels of potassium and unusually low levels of sodium (hyponatremia) and chloride (hypochloremia). However, not all dogs' electrolyte ratios are affected during an Addisonian episode.[10] Therefore, the only accurate test for Addison's disease in canines is an ACTH stimulation test.[7][9][24] While most corticosteroid drugs will invalidate the results of an ACTH test, Dexamethasone may be used in the event of an Addison's emergency without fear of compromising the results of the test.[25]

In general, Addison's disease in canines is underdiagnosed,[26] and one must have a clinical suspicion of it as an underlying disorder for many presenting complaints. Females are overrepresented,[14] and the disease often appears in middle age (four to seven years), although any age or gender may be affected.[27] Dogs with Addison's disease may also have one of several autoimmune disorders.[27] Because it is an endocrine disorder, they may also suffer from neuropathy and some endocrine-related eye diseases.[2

Treatment

Hypoadrenocorticism is treated with fludrocortisone (trade name Florinef)[36][37] or a monthly injection called Percorten-V (desoxycorticosterone pivalate, DOCP) and prednisolone.[38][39][40] Routine blood work is necessary in the initial stages until a maintenance dose is established.[9] Most of the medications used in the therapy of hypoadrenocorticism cause excessive thirst and urination. It is absolutely vital to provide fresh drinking water for a canine suffering from this disorder.[22]

If the owner knows about an upcoming stressful situation (shows, traveling etc.), the animals generally need an increased dose of prednisone to help deal with the added stress. Avoidance of stress is important for dogs with hypoadrenocorticism. Physical illness also stresses the body and may mean that the Addison's medication(s) need to be adjusted during this time.[41] Most dogs with hypoadrenocorticism have an excellent prognosis after proper stabilization and treatment.[7][24][23]

Susceptibility of certain breeds

Certain breeds are more susceptible than others to Addison's disease:[9][10]

Great Danes
Newfoundlands
Portuguese water dogs[7][16]
Standard poodles[7][17]



West Highland white terriers
Bearded collies[18]
Rottweilers[7]
English Springer Spaniels



German Shorthaired Pointers
Soft-Coated Wheaten Terrier
German shepherds
St. Bernards