Veterinary Medicine - February 2008 - (Page 93) marrow, and kidney grafts have all been successfully transplanted. Kidney allograft transplantation has been successful in both dogs and cats, although canine kidney transplantation presents a greater challenge because of the level of immunosuppression required to prevent allograft rejection.10,11 Rejection episodes in dogs are frequent and severe, and canine recipients require multiple-agent immunosuppressive protocols and intensive management.10,12 Several recent studies have explored triple-drug (cyclosporine, azathioprine, and prednisolone) protocols and histocompatibility matching with limited success; to date, high complication and mortality rates in dogs still preclude widespread use of kidney transplantation.12 However, kidney allograft transplantation in cats has become an accepted treatment for patients with end-stage kidney disease. In a study of 66 cats receiving kidney transplants at the University of California-Davis School of Veterinary Medicine, 71% of the cats survived until discharge.13 The one-year survival rate in this early case series was 51%, but advances in surgical technique have anecdotally resulted in greater survival times.14,15 tis, pyelonephritis, amyloidosis, oxalate nephrosis, renal dysplasia, pyogranulomatous nephritis, or nephrosclerosis secondary to drug toxicosis.14,16 MEDICAL MANAGEMENT OF CHRONIC KIDNEY DISEASE Medically managing cats with chronic kidney disease begins by identifying the underlying cause of kidney dysfunction. maintaining appetite and body weight. It is important for cats with mild to moderate chronic kidney disease to maintain adequate caloric intake to avoid protein malnutrition. Protein, phosphorus, and sodium restriction should begin when azotemia persists in the well-hydrated state (IRIS stage 2 disease).18 Proteinuric cats may bene t from treatment with an angiotensin-converting enzyme inhibitor Kidney transplantation is indicated in cats with decompensated chronic kidney disease or, less commonly, acute, irreversible renal failure. In a study of kidney biopsy ndings in cats with chronic kidney disease, tubulointerstitial nephritis was observed in 70% of cats, glomerulonephropathy in 15%, and lymphoma in 11%.17 But keep in mind that both tubulointerstitial nephritis and glomerulonephropathy are histologic rather than etiologic diagnoses. Serial assessment of any cat with chronic kidney disease is required to tailor therapy and provide prognostic information. Direct therapy at slowing the progression of disease through supportive and symptomatic therapy. The cornerstone of patient management is a combination of dietary and drug therapy, which minimizes the clinical and physiologic consequences of reduced renal function. such as benazepril, although a de nitive bene t is still lacking.19,20 Ensure adequate hydration Adequate hydration is equally important for maintaining renal function. Polyuric, uremic cats are prone to dehydration, which contributes to progressive renal dysfunction. Strategies to improve water consumption include providing fresh water, using drinking fountains, and feeding a canned food diet. Subcutaneous uid administration may be indicated with progression of renal insuf ciency or uremia since uid administration may help maintain optimal hydration and improve the quality of life for many cats. INDICATIONS Kidney transplantation is indicated in cats with decompensated chronic kidney disease or, less commonly, acute, irreversible renal failure. The critical rst step for ensuring a successful outcome is appropriate patient selection. Cats whose renal function continues to decompensate despite aggressive medical management are candidates for kidney transplantation. The most common pathologic conditions for which kidney transplantation is performed include chronic interstitial nephritis (48%), polycystic kidneys (10%), ethylene glycol toxicosis (9%), and renal brosis (6%).13 However, transplants have also been performed in cats with advanced kidney disease due to glomerulonephri- Treat anemia Anemia develops in later stages of chronic kidney disease as a multifactorial consequence of decreased erythropoietin production by the failing kidneys, decreased erythrocyte survival due to uremic toxins, and gastrointestinal bleeding. Recombinant human erythropoietin administration is effective in correcting nonregenerative anemia in most cats with Provide the right diet Dietary recommendations vary based on the International Renal Interest Society (IRIS) stage of disease, but once azotemia is present, a diet formulated for kidney disease management is recommended.18 A delicate balance exists between reducing protein intake and VETERINARY MEDICINE February 2008 93
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