Cushing’s (Hyperadrenocorticism) is a hormone disease which arises when the adrenal glands produce too much of the steroid hormone cortisol. Whilst cortisol is needed by every cell in the body, too much cortisol can have harmful effects.
Medical therapy with Trilostane is the most common treatment for Cushing’s.
Trilostane comes in the form of oral capsules which are taken once daily.
It can take several months to find the appropriate dose of Trilostane for your dog.
Surgery is a treatment option for those with an adrenal or a pituitary gland tumour but will involve referral to a specialist surgeon.
Treatment depends on the type of Cushing’s disease diagnosed.
Pituitary-dependent disease – caused by a tumour in the pituitary gland in the brain.
Adrenal-dependent disease – caused by a tumour in the adrenal gland itself
Iatrogenic disease – caused by too much steroid medication
This is the most widely used treatment method and is used to treat the most common form of Cushing’s –pituitary-dependent disease. It can also be used to treat adrenal dependent disease too.
The medication contains the active ingredient Trilostane,which reduces the production of cortisol by the adrenal gland. This medication comes in the form of oral capsules, which are taken once daily.
During the early stages of starting medication, your dog will require regular trips to the vet. This to make sure they are getting enough medication, and also to check they are not getting too high a dose.
Your dog will be started on a low dose of Trilostane, and your vet will usually want to examine your dog 10-14 days later. At this point they will probably want to take bloods to check the liver, kidneys and electrolytes (salt levels) and also perform an ACTH stimulation test to ensure they are on the correct dose of Trilostane. They will also ask about your dog’s symptoms. The dose will be gradually adjusted depending on their response to the treatment, and your dog will need to have repeat examination and blood tests at the vets every 10-12 days after each dose adjustment.
Once your vet is happy your dog is on the correct dose of medication, the check-ups can be extended to every 3 months.
It is important to note that monitoring the clinical signs (symptoms) in your dog is just as important as blood test results in assessing their response to the medication. The Royal Veterinary College (RVC), London have developed a ‘quality-of-life’ questionnaire - “The CushQoL-pet questionnaire” - which is designed to track your dog’s most important symptoms of Cushing’s. It is advised to perform this questionnaire on a regular basis, such as just before a vet visit, so that your dog’s progress can be tracked over time. This will help highlight if any adjustments need to be made.
Are there any treatment complications?
Trilostane is usually well tolerated by most dogs and treatment is successful in the majority of cases.
Side effects are uncommon, but include vomiting, diarrhoea, lethargy or going off their food. If any of these are experienced, stop the medication immediately and contact your vet.
However, in some cases, starting Trilostane medication can “unmask” other underlying diseases - this means that the symptoms of these diseases were less obvious because of the high levels of cortisol. Some of the diseases include osteoarthritis and allergic skin conditions, which may then require treatment or management.
For some forms of Cushing’s disease, surgery is a treatment option.
If your vet has diagnosed Cushing’s caused by a tumour on the adrenal gland (adrenal-dependent Cushing’s), your vet will discuss with you the option of surgery. This involves major abdomen surgery to remove the adrenal gland, usually requiring referral to specialist surgeons. If the tumour has not spread to any other areas of the body, this form of treatment can be very successful. When surgery is not an option, adrenal-dependent Cushing’s can usually be controlled well with medication.
A small number of cases of pituitary-dependent Cushing's may be given the option of surgery. This happens very rarely as it requires very specialist brain surgery to remove the tumour from the pituitary gland, and also because in most cases it can be managed well with medication.
Iatrogenic Cushing’s Treatment
Iatrogenic Cushing’s is caused by too much steroid medication, so the treatment involves stopping the medication. This must be done in a very controlled and gradual manner, otherwise it can lead to further complications. In some cases where steroid treatment has caused long-lasting effects on the adrenal gland, your dog may require medication as well, to help control the signs of Cushing’s.
Cushing’s disease is complicated and all cases are different, so if you wish to discuss your dog’s Cushing’s disease or their treatment options, one of our vets will be happy to help!