Robert Armentano DVM, DACVIM
Hyperadrenocorticism (HAC), or Cushings disease, is a very common hormone disorder in dogs and with proactive, routine testing is often diagnosed as an incidental finding. Pets with active clinical signs require testing and treatment but pets with subtle or no overt signs of HAC can be much more challenging. Due to vigilant owners and veterinarians many of these dogs are being worked up and evaluated based on annual blood work changes and potentially very subtle signs at home.
The most common referral concern for these dogs is blood work changes such as an increased ALP. Other causes may include incidental adrenal gland enlargement, high blood lipids, and bile duct disease changes on blood work. The work-up for HAC as determined by the ACVIM consensus statement does not recommend further HAC testing without a clinical patient but those boundaries have become much less black and white. Blood work results by themselves are not indicators for testing, however once diagnostic results are suggestive of HAC or if very subtle signs are noted it is sometimes challenging to know which dogs warrant further assessment.
Common screening tests include a urine cortisol:creatinine ratio, ACTH stimulation test or a low dose dexamethasone suppression test. If a dog has the clinical syndrome consistent with HAC and tests to confirm it, treatment is warranted. It is challenging to decide if a patient with subclinical signs/findings warrants treatment. In any patient, the risk and benefits of therapy should be discussed particularly if we are discussing treating a disease simply to alleviate concerns for a comorbid condition.
There are many studies to show associated comorbidities with Cushing’s disease. Most importantly, however, many have not proven that by treating Cushing’s disease that the comorbid condition chances necessarily decrease. The most common comorbid conditions include diabetes mellitus, urinary tract infections, urolithiasis, skin infections, hypertension, gallbladder mucoceles (blockages), ligament rupture, thromboembolic disease (blood clotting problems), proteinuria (protein spillage into urine) and pancreatitis. When making recommendations to clients with dogs that have asymptomatic HAC but blood work/imaging changes consistent with the disease it is important to assess the pros and cons of treatment.
Based off of the most recent data there is limited overwhelming evidence that by treating an asymptomatic patient but with comorbid conditions that things will improve. Most data is anecdotal. There is some supportive evidence that lysodren therapy could help decrease that overall diabetic incidence in 13% of dogs. Statistically, treatment for Cushing’s disease may help decrease the incidence of gall bladder disease in 26.6% of patients. Hypertension and proteinuria improved in 47% with treatment, and 60-80% in other references.
All other comorbidity improvement is anecdotal or not likely to help with treatment. If a supportive plan is not helping or if the pet becomes more clinical then treatment can be pursued. If supportive care is elected it is not uncommon for patients to be on a few medications for their various co-morbidities associated with HAC. When supportive care is elected monitoring is often less invasive and more cost effective. If patients are on supportive medications reassessment with blood work, blood pressure, and UPCs are recommended every 3-6 months depending on the severity of the co-morbidity.
Dr. Robert Armentano is an Internal Medicine Specialist at Veterinary Specialty Center.