There are some diseases I just despise. It’s not that I like any disease, but some just make me want to crawl in a hole. Cushings disease is one of them. Cushings is short for hyperadrenocortisism, a state where the body makes too much steroid, either from a pituitary tumor or from an adrenal tumor. The tumor can be benign or malignant, but regardless the excess steroid can wreak havoc on the pet. It’s usually a forever treatment for the life of the pet (except for the less common adrenal mass that sometimes can be surgically removed), and it’s very expensive to treat. If you think treating diabetes is expensive, you should see the bills that pile up with Cushings disease! The initial and ongoing blood tests are expensive. The medication is expensive. And the vast majority of pets affected will be a ‘Cushingoid’ for life, requiring the medication for life. You see why I despise this disease!

Why am I going on about one of my least favorite diseases? Because there is a link between Cushings disease and diabetes. Cushings patients produce too much steroid. Steroids cause insulin resistance. Some diabetic pets actually became diabetic secondary to having Cushings disease from the insulin resistance caused by steroids. It is difficult to regulate a diabetic pet that is also Cushingoid. There are a few things you should know about this disease if your pet is diabetic.

Cushings can affect both dogs and cats, but it is better understood and much more common in our canine friends than our feline friends. Personally, I think it is often more affordable for families to go straight to an internist rather than have their regular veterinarian diagnose and treat this disease. Additionally, treatment of this Cushingoid state can result in a crisis situation and requires very close monitoring, ideally by someone well-versed in the disease. A general practitioner like me might come across one or 2 Cushingoid dogs per year, but internists manage many Cushingoid pets all the time. When dealing with diagnostic and ongoing monitoring tests that are as costly as with this disease, you want a specialist (or at least a GP who sees a lot of them) to manage your pet. Medicine is getting so specialized that as my neighbor once put it, “If you have one doctor to treat your right foot you need a second doctor to treat your left foot”.

Personally, when I suspect Cushings disease I send the pet to my local internist. I’m very lucky that I have an amazing veterinary internist just a couple miles from my general practice, and his practice is open 24/7. With that being said you will understand that I am not a pro at this disease. Nonetheless, I can point out important points I think a layperson with a diabetic pet should know.

How do we treat Cushings disease? For years vets used a drug called Mitotane which selectively destroyed part of the adrenal gland. It required daily vet contact at initiation of treatment as Mitotane could cause adrenal necrosis and a pet could go into a medical crisis and die if left untreated. Yikes! A new medication called Trilostane is now available to treat Cushings. Trilostane came out about 8 years ago and is less likely to cause adrenal necrosis, although it is still feasible. Trilostane reversibly inhibits the production of cortisol in the body. I don’t feel quite so strongly about referral to an internist these days as I used to back when all vets had in our tool kit was Mitotane. Most vets use Trilostane now.

So here goes with the nitty gritty bullet points on Trilostane!

  • Give Trilostane with food. It is absorbed 3 times better with food than on an empty stomach. For a diabetic pet this means at mealtime the pet should get the Trilostane and insulin at the same time, when Fluffy is eating.
  • When your vet does the monitoring blood work (chemistry, electrolytes and a test called an ACTH stim), give the Trilostane in the morning. The ACTH stim should be done 4 to 6 hours after the Trilostane is given. If you give Trilostane at the evening meal that means you’d need to do the ACTH stim test at midnight for an accurate result. That would make your vet grouchy!
  • Don’t break apart the capsules. You are treating Fluffy, not yourself. You don’t want to affect your own hormones!
  • Some vets get Trilostane compounded to save their clients money. It’s important that they check with the compounding pharmacy to verify they are using medical grade Trilostane rather than chemical grade. Unfortunately, a good chunk of the expense of treating these patients is the re-check lab work (up to every 3 months for the life of the pet). Compounding probably isn’t worth the minor savings. I’d stick with the brand name stuff with this disease. The one brand available in the USA is called Vetoryl.
  • Sometimes pets feel puny at the start of treatment. This may simply be from steroid withdrawal. Be prepared for this and know it will get better. On the other hand, the diabetes will be easier to control and the pet may feel better without overt steroid withdrawal signs. Anticipate lowering the insulin dosage as the steroid production comes down to normal! Keep a very close watch on the blood glucose and adjust the insulin accordingly to avoid hypoglycemia.
  • According to Dechra, the manufacturer of Vetoryl, 4 of 5 pets do well getting Trilostane once a day. That leaves 1 of 5 needing it twice daily. Diabetic pets should get it twice daily. Why? It’s about the duration of a dose. The dose is quickly absorbed orally and is out of the body in 10 to 18 hours. Nondiabetic pets might be okay with a little excess steroid for the last part of a 24 hour period. Diabetics don’t do well with any excess steroid!
  • If your pet is diabetic AND Cushingoid, the total daily dose should be split in 2 and given 12 hours apart.
  • Can we use Trilostane in cats? Some vets have used Trilostane on cats, but it is extralabel use for felines. Cushings disease is a known disease in cats but is much less common than in dogs. If your diabetic cat is difficult to regulate despite your best efforts, your vet may contemplate the possibility of concurrent Cushings disease.

As always, I enjoy getting emails from readers. Feel free to email me at

NOTE: Consult your veterinarian first to make sure my recommendations fit your pets special health needs.

Dr . Joi Sutton

Dr . Joi Sutton

Dr. Joi Sutton is a 1993 graduate from Oregon State University. She has practiced both in emergency medicine and general practice. Dr. Sutton has done extensive international volunteer work though Veterinary Ventures, a nonprofit organization that takes teams of veterinarians to undeveloped countries for humane medical care. She also runs a small animal practice in South Florida.
Dr . Joi Sutton

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