Cushing's disease or hyperadrenocorticism is a relatively common disease in middle aged and older dogs. The disease is the result of excessive levels of substances called corticoids in the bloodstream. Certain breeds seem more prone to Cushing's, in particular poodles, terriers, dachshunds, beagles and labradors.
Typical signs of this disease include increased water intake (and consequently increased urination), increased appetite, muscle wastage and weakness. Dogs may also become pot-bellied, bruise more easily and lose coat condition.
Basic blood screens and analysis of a urine sample can raise suspicion of hyperadrenocorticism but a more specific blood test is needed to confirm the condition. This involves taking a blood sample, measuring the cortisol level in that sample, giving an injection to stimulate a change in the cortisol level (what the injection is depends on the type of test that is carried out) and then taking another blood sample and short time later to assess how the body has reacted to the injection.
Once the diagnosis has been confirmed, hyperadrenocorticism can usually be treated successfully with daily tablets. Different dogs respond differently to the tablets, so once treatment is started it is generally necessary to retest the blood at intervals until the ideal dose is found for that particular animal.