No specific protocol is required for recovery or monitoring of the donor cats in the immediate postoperative period. These
patients are managed routinely as with any other post-laparotomy patient (e.g. incision care, analgesia). Transplant institutions will recheck donor patients' serum creatinine concentrations before discharging
the cats to their new owners.
Immediate postoperative complications
Immediate postoperative complications including acute graft rejection, hypertension, and neurologic signs have been reported,
although immunosuppressive protocols have vastly decreased the incidence of acute rejection episodes.13,46,47 Nineteen presumptive episodes of allograft rejection were noted in 12 of 66 (18%) cats, most commonly in the first two months
after surgery.13 Antirejection therapy in cats consists of methylprednisolone sodium succinate, with some transplant centers also giving
intravenous cyclosporine to maintain therapeutic serum concentrations.38 Reactivation of chronic feline respiratory viral infections can also be a serious complication.32
Hypertension is a common complication that can occur intraoperatively as well as shortly after surgery. Severe postoperative
hypertension requiring intervention (systolic blood pressure > 170 mm Hg) was documented in 62% of recipient cats.46 Managing hypertension has also been shown to significantly reduce the prevalence of neurologic complications.46 Central nervous system disorders have been reported in 21% of cats receiving transplants, with seizures occurring in 88%
of these cases.47
LONG-TERM MANAGEMENT AND COMPLICATIONS
Recipient cats. Patients are discharged from the hospital when the graft function appears satisfactory and blood cyclosporine concentrations
are stable. Satisfactory graft function is indicated by an adequate nutritional intake and urine concentrating ability, a
decreased serum creatinine concentration, and a good attitude.
Successful long-term survival of transplant patients is achieved with good patient and client compliance and continued care
by the transplant center, primary care veterinarian, and local emergency clinics. Perform weekly examinations for four weeks.
At each visit, determine serum creatinine concentrations, PCV, total solids concentration, body weight, and whole blood cyclosporine
concentrations. Subsequently, perform a complete blood count, serum chemistry profile, urinalysis, urine culture, and cyclosporine
concentration several times per year. Rechecks should occur frequently (every two to three months minimum) in the first year
after surgery, with more frequent rechecks in patients exhibiting any signs of illness; less frequent rechecks (every three
to four months) are indicated in future years.
Aside from the complications discussed in the immediate postoperative period, several long-term adverse effects have been
documented. Transplant recipients have an increased susceptibility to infection, presumptively because of immunosuppressive
therapy.32 Viral, bacterial, parasitic, coccidial, protozoal, and fungal infections can develop and require unusually intensive treatment
and supportive care. Urinary tract infections are most common; antimicrobial therapy should be considered with special concern
for any potentially nephrotoxic drugs or drugs that may alter the half-life of cyclosporine. Because of their increased susceptibility
to infection, transplant recipients should be housed exclusively indoors. Use standard parasite control and vaccination schedules
in these cats. However, killed or inactivated and recombinant or subunit vaccines should be administered when possible rather
than attenuated or modified-live products.
Toxoplasmosis has been reported as a rare sequela to transplantation and may be due to transplanting a kidney from a healthy
but latently infected donor into an uninfected recipient or through reactivation of a latent infection in a recipient because
of immunosuppression.31
Transplant recipients are also at an increased risk for developing neoplasia, particularly lymphoproliferative neoplasms.48,49 In one retrospective study, nine of 95 cats (9.5%) developed malignant neoplasia after renal transplantation and immunosuppression,
a frequency higher than that expected in cats that do not undergo this procedure.48 Diabetes mellitus is also more common in transplant recipients, which further increases the risk of infection.50
Table 4 Institutions Performing Feline Renal Transplantation*
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Donor cats. The long-term risks associated with kidney donation in cats appear to be minimal. Donors presumptively have normal renal function
at the time of nephrectomy, and loss of 50% of functional nephrons should not result in azotemia or decreased urine concentrating
ability. No regular recheck examination schedule is usually recommended, but measuring a serum creatinine concentration and
urine specific gravity one to two months after surgery to establish a baseline, followed by yearly rechecks, is likely reasonable.
SUMMARY
Despite being a costly and medically intensive option, kidney transplantation has proved to be an effective method for treating
some cats with chronic kidney disease. The highest chance of success is achieved through careful patient selection and a close
working relationship among the client, primary care veterinarian, and surgical and internal medicine specialists. Standardized
preoperative screening and postoperative management protocols exist, with some variation, among institutions that offer kidney
transplantation (Table 4). The critical first steps to a successful transplantation are contacting an appropriate transplant center and optimizing
the candidate's overall health status.
Jason Bleedorn, DVM*
Barrak Pressler, DVM, DACVIM
Department of Veterinary Clinical Sciences
School of Veterinary Medicine
Purdue University
West Lafayette, IN 47904
*Current address: Department of Surgical Sciences School of Veterinary Medicine University of Wisconsin Madison, WI 53706
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