Upon admission to the transplant facility, the recipient is typically placed on intravenous fluid therapy of a balanced electrolyte solution at 1.5 to two times the daily maintenance requirements.
This rate may vary in cases of severe dehydration or in cats with underlying cardiac disease. Additionally, if the cat is hypertensive, the drug amlodipine (Norvasc) may be indicated before surgery. Anemia is typically corrected at the time of surgery with cross-match compatible whole blood or packed red cell transfusions.
If the patient is unstable with respect to the anemia, blood products can be given at the time of admission to the transplant facility. If a delay in the transplant procedure is expected, erythropoietin (Darbepoetin 5-6.25 mcg/cat once weekly) can be administered. Please speak to transplant staff before administering this.
Phosphate binders and gastrointestinal protectants are given if deemed necessary and if the cat is anorectic, a feeding tube may be placed to administer nutritional support prior to surgery.
A combination of Cyclosporine and prednisolone are currently used for immunosuppression at our facility. Cyclosporine administration is begun 72 to 96 hours prior to transplantation at a dose of 1-4mg/kg PO q12h depending on the cat’s appetite. It has been the author’s experience that cats that are anorexic or eating a minimal amount have a much lower drug requirement to obtain appropriate drug levels prior to surgery.
A 12-hour whole-blood trough concentration is obtained the day before surgery so that the dose can be adjusted prior to surgery if necessary. Using the technique of high-pressure liquid chromatography (HPLC), the goal is to obtain a trough concentration of 300 to 500ng/ml for surgery. This level is maintained for approximately one to three months following surgery and is then tapered to approximately 250ng/ml for maintenance therapy.
There seems to be very little correlation between the oral dose of Cyclosporine and the blood level that will be achieved in a particular patient. Two 4kg cats can be given the same oral dosage and their blood levels may be entirely different. Because of inter-patient and intra-patient variability in the absorption of oral Cyclosporine and its metabolism, blood levels should be monitored regularly to maintain therapeutic concentrations and minimize toxic side effects.
Prednisolone is administered beginning the morning of surgery. At our facility, prednisolone is started at a dose range of 0.5-1mg/kg q12h orally for the first three months and then tapered to q24h.
If renal function starts to deteriorate in the first weeks to months following transplantation, Azathioprine (0.3mg/kg/72 hours) may be added to the immunosuppressive protocol. Cats receiving Azathioprine should have their white blood cell count monitored regularly.