Veterinary Medicine - February 2008 - (Page 92) CE PEER-REVIEWED 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. Jason Bleedorn, DVM, and Barrak Pressler, DVM, DACVIM K idney transplantation is a viable therapeutic alternative for cats with end-stage renal failure. The rst successful kidney transplantation in a cat was performed in 1987 at the University of California-Davis School of Veterinary Medicine.1 Veterinary surgeons at transplant centers across the country have since performed several hundred successful kidney allograft transplants in cats. Not all patients with chronic kidney disease are good candidates for kidney transplantation, and postoperative care requires intense medical management. In this article, we review the indications, diagnostic evaluation, and complications of kidney transplantation in cats. We also brie y describe the medical and surgical management of these patients. CHRONIC KIDNEY DISEASE: A COMMON CAUSE OF MORBIDITY AND MORTALITY Chronic kidney disease is a progressive, irreversible condition that affects a large 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 percentage of cats. It is among the most common diseases in older cats, with a reported prevalence of 1.6% to 20%.2,3 One study reported the prevalence of renal failure was 12% in all cats examined at a referral-based veterinary teaching hospital.4 In geriatric cats older than 15 years, the prevalence increased to slightly greater than 30%. Chronic kidney disease is characterized by functional or structural injury that has resulted in irreversible histologic changes. Kidney function is evaluated by performing a complete blood count, a serum chemistry pro le, a urinalysis, and diagnostic imaging. Changes in blood urea nitrogen and creatinine concentrations and possible abnormalities in serum phosphorus concentrations, other electrolyte concentrations, and hematocrit or packed cell volume (PCV) combined with decreased urine concentrating ability are commonly used to assess the severity and progression of disease. Fortunately, the kidneys have a tremendous reserve capacity; however, this reserve can delay the diagnosis of acute or chronic kidney disease until marked damage has occurred. Inadequate urine concentrating ability is generally associated with a loss of two-thirds of functional nephrons, while a loss of threefourths of functional nephrons results in azotemia. Cats may maintain some concentrating ability despite azotemia and, thus, may be in overt renal failure without isosthenuria. By the time renal dysfunction is detected by using standard clinicopathologic tests, clinicians must assume that kidney disease is severe. In some cats, kidney transplantation offers successful treatment. HISTORY OF KIDNEY TRANSPLANTS Organ transplantation was rst attempted early in the 20th century, using animal models. Kidney allograft transplantation (organs from other individuals of the same species) was rst described by Alexis Carrel, who pioneered many vascular surgical techniques still used today.5 Early transplants were technically successful, although the transplanted kidney allografts were inevitably rejected. It was not until the development of immunosuppressive drugs in the early 1960s that prolonged survival was achieved.6 Cyclosporine revolutionized kidney transplantation through its selective inhibition of T lymphocytes, the main cell type responsible for kidney allograft rejection.7,8 Kidney transplantation is the treatment of choice in many people with end-stage kidney disease. It is an attractive alternative to hemodialysis or long-term peritoneal dialysis since quality of life and survival are greater. The transplant patient mortality rate is less than 5% in the rst year.9 This success rate is a re ection of extensive research in immunosuppressive therapy and recipient-donor matching. Live donor allografts remain superior to cadaveric grafts, but 60% of patients still receive grafts from human cadavers because of insuf cient donor numbers.9 Over the last decade, organ transplantation in veterinary medicine has become more common. Corneal, bone 92 February 2008 VETERINARY MEDICINE
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