In cases with a congenital cardiac condition, I always try to have a cardiac ultrasound performed to establish baseline and severity of the condition. Thereafter, if any other medication/treatment/etc. is ever used I then have a comparison to the original defect.
It is also important to establish the cause of the chronic skin condition in order to determine the best and safest treatment given the constraints of this patient. Cortisone may indeed be the safest/best treatment for this skin problem, however this assumes you've met the previous conditions: finding out just exactly what these lesions are, and how bad is the cardiac problem.
It is very tempting in medicine to act precipitously before all the data is in, and no end of mischief results from incomplete assessment. I would ask for a cardiac consult first, and then biopsy with a local anesthetic a representative skin lesion, in addition to a skin culture to rule out the more common skin infections such as streptococci or staphlycocci bacteria. Immune impairment is a very common reason for chronic skin infections.
Not to be overlooked would be common ecto-parasites such as fleas and lice. I realize this is a Rex and these parasites are readily apparent...but never overlook the obvious. Other skin lesions are sebaceous and follicular in origin and have a seperate treatment regimen.There are a large number of other reasons for these lesions. Discuss a work-up plan with your veterinarian.
Dr. Van Lienden
Dr. Raymond Van Lienden DVM
The Animal Clinic of Clifton
12702 Chapel Road, Clifton
Virginia, U.S.A. 20124