Screening and medical management of feline kidney transplant candidates - Veterinary Medicine
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Screening and medical management of feline kidney transplant candidates
Hundreds of cats with failing kidneys have successfully recovered after undergoing this life-saving procedure. Find out how to determine whether some of your feline patients would make good candidates and how to monitor transplant recipients long-term.


VETERINARY MEDICINE


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*
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

REFERENCES

1. Gregory CR, Gourley IM, Kochin EJ, et al. Renal transplantation for treatment of end-stage renal failure in cats. J Am Vet Med Assoc 1992;201(2):285-291.

2. Lund EM, Armstrong PJ, Kirk CA, et al. Health status and population characteristics of dogs and cats examined at private veterinary practices in the United States. J Am Vet Med Assoc 1999;214(9):1336-1341.

3. Watson A. Indicators of renal insufficiency in dogs and cats presented at a veterinary teaching hospital. Aust Vet Practit 2001;31:54-58.

4. Lulich J, Osborne C, O'Brien T, et al. Feline renal failure: questions, answers, questions. Compend Contin Educ Small Anim Pract 1992;14:127-153.

5. Carrel A. Transplantation in mass of the kidneys. J Exp Med 1908;10:98-140.

6. Aisenberg AC. An introduction to immunosuppressants. Adv Pharmacol Chemother 1970;8:31-55.

7. Flechner SM. Cyclosporine: a new and promising immunosuppressive agent. Urol Clin North Am 1983;10(2):263-275.

8. Calne RY, White DJ, Thiru S, et al. Cyclosporin A in patients receiving renal allografts from cadaver donors. Lancet 1978;2(8104-8105):1323-1327.

9. U.S. Renal Data System, USRDS 2006 Annual Data Report: Atlas of End-Stage Renal Disease in the United States, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, 2006.

10. Gregory CR, Kyles AE, Bernsteen L, et al. Results of clinical renal transplantation in 15 dogs using triple drug immunosuppressive therapy. Vet Surg 2006;35(2):105-112.

11. Gregory CR, Gourley IM, Haskins SC, et al. Effects of mizoribine on canine renal allograft recipients. Am J Vet Res 1988;49(3):305-311.

12. Mathews KA, Holmberg DL, Miller CW. Kidney transplantation in dogs with naturally occurring end-stage renal disease. J Am Anim Hosp Assoc 2000;36(4):294-301.

13. Mathews KG, Gregory CR. Renal transplants in cats: 66 cases (1987-1996). J Am Vet Med Assoc 1997;211(11):1432-1436.

14. Aronson LR, Kyles AE, Preston A, et al. Renal transplantation in cats with calcium oxalate urolithiasis: 19 cases (1997-2004). J Am Vet Med Assoc 2006;228(5):743-749.

15. Mehl ML, Kyles AE, Pollard R, et al. Comparison of 3 techniques for ureteroneocystostomy in cats. Vet Surg 2005;34(2):114-119.


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