yes, in ferrets they are relatively common(usually 3+ years of age, but I've seen younger). It's been said that 70% of ferrets will have an adrenal gland growth at some point in their life. Adrenal gland tumors are usually benign(non cancerous) and surgery is curative. In cases where surgery is not an option due to an underlying medical problem(such as cardiomyopathy), a drug such as Lupron may be used. Lupron does not shrink the adrenal growth, it merely alleviates the symptoms associated with the disease. Chemo is almost never used with adrenal disease due to it's benign nature; and honestly chemo is far too stressful for ferrets, even with lymhosarcoma and most people opt not to use it. It very rarely works and does more harm than good.
There is a lot of speculation as to what causes adrenal gland disease. Some have said it's the early neutering/spaying practices of the ferret "mills". Improper photo periods(light cycles) have also been suspected as well as diet and various other notions.
Yes, I've had several ferrets with adrenal disease. My first ferret, Baby died last November from a combination of adrenal disease, cardiomyopathy, and lymphosarcoma
I had one of the few "malignant"(cancerous) adrenal ferrets pass away last year. He was diagnosed at 2.5 years of age. He survived 4 surgeries: adrenalectomy, removal of abcess on prostate, urethrostomy and marsupialization; and he lived 3+ longer than expected(he only had a month to live when he came to us as a rescue). His little body just couldn't take anymore. Very sad day here when he passed away
We have a rescue girl in right now who has adrenal gland disease and will be going for surgery soon. Ask any shelter operator and THE most common ailment is adrenal gland disease.
It has been said that European bloodline ferrets don't get or have very rare occurrences of adrenal gland disease(I've had no probs *yet* with my Euro ferrets), but it hasn't been scientifically proven.