Prolonging life and kidney function (Proceedings)
Evidence based medicine studies of clinical dogs and cats with chronic renal failure have emerged showing salutary effects of dietary modification. "Renal-friendly" veterinary diets are generally restricted in protein, phosphorus, calcium, and sodium while supplemented with carbohydrates, sources of alkali (potassium citrate), and polyunsaturated fatty acids in a favorable ratio of omega-6:omega-3 fatty acids. Traditionally, benefits of such diets are attributed to the well-known protective effects of dietary phosphorus restriction (with or without lowering of PTH), but diets with higher eicosapentaenoic acid content may also confer protection.
Compared to the average grocery or pet store foods, the renal friendly veterinary diets are restricted in protein by about ⅓ to ½, while phosphorus is restricted by 70 to 80%. Canned foods are generally more restricted in phosphorus than their dry counterparts and substantial differences exist amongst the available products. Dry but not canned food for cats is supplemented with potassium at about twice the level of maintenance foods apparently in an effort to avoid kaliopenic nephropathy. Comparison of nutrient intake on a mg/100 kcal energy intake basis for dogs and cats fed veterinary diets is available from the Nutrition Support Services web site maintained at The Ohio State University CVM (http://vet.osu.edu/nssvet/).Protein restriction should be considered when moderate to severe azotemia persists in the wellhydrated state. The clinician should strike a balance between reducing protein intake and the animal's willingness to eat. Maintenance of stable body weight and serum albumin concentration suggests adequate intake of calories and protein whereas progressive declines in body weight and serum albumin concentration suggest malnutrition or progression of disease and are indications to increase the amount of protein fed. If possible, the animal should be acclimated to the new diet while its appetite is still reasonably good. Recent studies have shown a beneficial effect of feeding commercially-available modified renal diets to dogs and cats with CRF to increase survival to at least twice that achieved with maintenance diet and to reduce the number or uremic crisis episodes.