Cushing's Disease is a uncommon condition 
in older dogs, often mistaken for the aging 
process itself.   Yet Cushing's disease is treatable,
and that treatment can result in a longer, more 
comfortable life for the dog and its owner. 

Cushing's Disease is one of the less common endocrine diseases of dogs.  An endocrine disease is a disease affecting one of the many glands that make hormones.  Hormones are chemicals that the body makes to regulate itself.  A more common example of an endocrine disease would be diabetes.  The pancreas makes insulin, which is a hormone that causes the cells to absorb glucose.  After meals, when the blood sugar levels rise, the pancreas releases insulin, which travels to all parts of the body and causes all the cells to absorb the glucose that is in the blood.  When the pancreas goes bad, not enough insulin is produced, and we have an abnormal condition known as an endocrine disease.

In the case of Cushing's Disease, the hormone in question is cortisol.  Cortisol is also known as adrenalin, and is a hormone made by the adrenal glands.  The adrenal glands sit just next to the kidneys, and in response to stress they produce cortisol.  Cortisol travels to all parts of the body, where it has many effects.  In patients with Cushings disease, too much cortisol is produced.  This abnormal condition is also called hyperadrenocorticism (hyper for hyper, adreno for adrenal, corticism for cortisone).

Cushing's Disease has many symptoms.  Cortisol has many target tissues, and it affects each target tissue in a different way.  Thus, we see many different symptoms in Cushingh's Disease.

The most common symptoms include:

        • increased/excessive water consumption (polydipsia)
      • increased/excessive urination (polyuria)
      • urinary accidents in previously housetrained dogs
      • increased/excessive appetite (polyphagia)
      • food stealing/guarding, begging, trash dumping, etc.
      • sagging, bloated, pot-bellied appearance
      • weight gain or its appearance, due to fat redistribution
      • loss of muscle mass, giving the appearance of weight loss
      • bony, skull-like appearance of head
      • exercise intolerance, lethargy, general or hind-leg weakness
      • new reluctance to jump on furniture or people
      • excess panting, seeking cool surfaces to rest on
      • symmetrically thinning hair or baldness (alopecia) on torso
      • other coat changes like dullness, dryness
      • slow regrowth of hair after clipping
      • thin, wrinkled, fragile, and/or darkly pigmented skin
      • easily damaged/bruised skin that heals slowly
      • hard, calcified lumps in the skin (calcinosis cutis)
      • susceptibility to infections (especially skin and urinary)
      • diabetes, pancreatitis, seizures 

There are also some other signs of Cushing's Disease that are only evident on blood tests.  We see elevations in liver enzymes (ALP, ALT, and AST),  decreased thyroid levels, a stress leukogram,  and high blood pressure.  There are so many different sypmtoms of Cushing's Disease that it is actually very uncommon for any one patient with Cushing's Disease to show all the symptoms at the same time.

It can be quite difficult to diagnose Cushing's Disease.  There are four different tests that can be used to test for Cushings' Disease:  the ACTH stimulation test, the Low-Dose Dexamethazone Suppression test, the High-Does Dexamethazone Suppression test, and the Urine Creatinine:Cortisol Ratio test.   Which one to use is a very complex decision, and involves both the art and the science of veterinary medicine.  It may take two different tests to become relatively sure our patient has Cushing's Disease.  Like many things in life, there are  no sure things, and we may never be 100% sure that a patient has or doesn't have Cushing's Disease.  We use our best judgement combined with common sense and a healthy dose of caution and treat the way we feel is best for the patient. 


Cushing's Disease is generally treated with a drug called Lysodren.  Although it is the best drug for treating this disease, Lysodren is not a nice drug.  It is fairly expensive, and has the added benefit of being somewhat toxic.  Lysodren selectively kills the adrenal galnds, which is just the ticket if they are making too much cortisol.  The goal is to kill just enough adrenal tissue to restore the cortisol levels to normal.  The trick is getting the just enough part right.  Every induvidual is different, and each requires a different dose.  Lysodren is given at a high, daily dose until enough adrenal tissue is gone to allow the cortisol levels to return to normal.  This is called the induction phase, and it can take anywhere from three days to three weeks.  Lysodren is given at a dose of 25mg per kilogram bodyweight every twelve hours immediately after a meal.  It is best to start Lysodren therapy on a Saturday to minimize the chances of having problems on a weekend.

It takes careful observation to tell when a patient has reached the end of the induction pahse.  Generally, we start dosing Lysodren at 25mg per kilogram of body weight every 12 hours.  Then we monitor very closely for signs that induction is over.  Dogs that get treated for Cushing's Disease are drinking a lot of water, and they have a voracious appetite.  When the water consuption OR the appetite decrease, we have reached the end of the induction phase.  We are not talking about major changes, either.  A slight decrease in appetite, say where the dog still eats well but does not wolf the food down like he did before is enough.  If you have any questions at all about whether your dog has reached the end of the induction phase, please call immediately and discuss your observations with the veterinarian.  If your dog has not responded to Lysodren therapy by eight of ten days, we will need to examine him or her, and we may perform the ACTH stimulation test at that point if there are any questions as to what is going on.

There are serious consequences for over-shooting the induction phase end-point. If we over-shoot the end-point, we will see signs of toxicity.  Sings of toxicity include lethargy, staggering or incoordination, weakness, loss of appetite, vomiting, and/or diarrhea.  If you see any of these symptoms, call the veterinarian immediately.  We often send home a small supply of a drug called prednisone.  This is a rescue drug that can be given if we have signs of toxicity.  Give the prednisone only if the veterinarian directs you to give it.

When we think we have reached the end of the induction phase, we do an ACTH stimulation test to find out for sure.  If the test shows good control, we will enter the maintenence phase.  In the maintenance phase,  Lysodren is given at a dose of either 25mg or 50mg per kilogram bodyweight once a week, depending on how soon your dog responded to the induction phase.  It is still a good idea to give it just after a meal.  If signs of toxicity develop, lethargy, staggering or incoordination, weakness, loss of appetite, vomiting, and/or diarrhea, contact the veterinarian immediately.  Similarly, be sure and notify the veterinarian if signs of increased water consumption or increased appetite develop.  

The prognosis for dogs with Cushing's Disease is good with treatment.   We expect symptoms of Cushing's to fully resolve over the course of 4-6 months. Excess drinking and urinating abate quickly. It may take several months for hair and coat improvement to be observed. Dogs generally are more comfortable after the disease is under control and may live happily for years. However, Cushing's disease is managed, not cured, and maintaining a dog with Cushing's disease requires vigilance and commitment on the part of the owner.  

Left untreated, Cushing's disease will progress. As excess cortisol is immunosuppressive, Cushingoid dogs are prone to various infections. They are also predisposed to developing hypothyroidism, pancreatitis, diabetes, seizures, hypertension, congestive heart failure, blood clots, and liver and kidney failure. It should not go without noting that many of these dogs are at risk of early euthanasia due to incontinence resulting from increased water consumption.  Although the treatment for Cushing's Disease is not without it's own problems, the treatment is much better than the disease, and treatment will prolong the patient's life and improve the quality of life as well.

Lysodren is not an inexpensive drug.  The last time I checked, it cost somewhere around $5.25 per pill.  For a twenty-pound dog who would get one-half tablet every twelve hours during the induction phase, assuming induction took eight days, it would cost about $45.  Maintenence for that same dog would be either $10.50 or $21.00 a month, dpending on the maintenence dose.

It is important to monitor dogs on Lysodren periodically.  Generally, we need to repeat the ACTH stimulation test every 6 to 12 months.  If signs of problems develop, we will also need to repeat the ACTH stimulation test.  All older dogs, especially those with Cushing's Disease, need to have annual bloodwork done.