Today's Veterinary Practice

NOV-DEC 2018

Today's Veterinary Practice provides comprehensive information to keep every small animal practitioner up to date on companion animal medicine and surgery as well as practice building and management.

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PEER REVIEWED 16 NOVEMBER/DECEMBER 2018 Once a nutritional recommendation is made, the patient should be monitored, with feeding recommendations adjusted as needed ( TABLE 2 ). Among nutritional recommendations, the most controversial may be that for protein. Historically, veterinarians were taught to reduce dietary protein upon diagnosing CKD, but that long-held assumption is changing. Without evidence that dietary protein reduction slows progression, the goal should be to feed a level of protein that meets the cat's needs while minimizing phosphorus. Dietary management alone will not prevent or reverse sarcopenia or cachexia, but calorie and/or protein deficiencies will certainly worsen it. 5 Weight loss in cats with CKD is associated with a lower survival rate, 10 which supports the importance of assuring adequate calories and protein intake in addition to phosphorus restriction. The introduction of newer therapeutic diets allows for customization of dietary recommendations for early- and late-stage CKD patients. TABLE 2 Nutrient Modifications of Therapeutic Renal Diets for Cats With CKD NUTRIENT RECOMMENDATION RATIONALE Phosphorus Restrict in all stages of CKD; typical range of phosphorus restriction is 80–135 mg/100 kcal Phosphorus promotes progressive damage to the kidney. Failure to excrete excess phosphorus leads to release of parathyroid hormone and secondary renal hyperparathyroidism Protein ■ Early stages: Avoid excess levels but may not restrict (provide ~5.4 g protein/kg body weight/day) ■ Late stages: As disease progresses, reduce protein to minimize signs of uremia ■ Feed high-quality protein in all stages of disease ■ Feed moderate amounts of high-quality and highly digestible protein to prevent protein deficiency and help maintain lean muscle mass in early stages of CKD; geriatric cats require more protein than younger animals because of higher protein turnover 5 ■ Later in the disease process, reducing protein minimizes production of filtered nitrogenous waste products ■ Regardless of levels, high-quality protein (highly digestible and complete) meets protein requirements and minimizes loss of lean body mass Potassium Increase levels of dietary potassium, particularly in late stages ■ Hypokalemia is a common feature of cats with CKD, particularly in late stages ■ Low potassium can cause cats to feel unwell, but its effects on progression are unclear 6,7 Sodium Control levels to avoid excess Avoiding excesses is advised, but there is no evidence that restriction is necessary Omega-3 fatty acids Increase levels in all stages of CKD Omega-3 fatty acids can increase renal blood flow, minimize hypoxic damage to tubulointerstitium, 8 and possibly reduce inflammatory mediators Antioxidants Increase levels in all stages of CKD Antioxidants reduce hypoxia and oxidant damage associated with CKD 9 Water-soluble vitamins Increase levels in all stages of CKD Supplementation of water-soluble B vitamins can help compensate for levels depleted because of CKD-related polyuria The Obesity Paradox: A Cushion Against Morality? Obesity can be a complex issue to manage in cats with early CKD. On the one hand, obesity contributes to such conditions as osteoarthritis, diabetes, and urinary tract disease. On the other hand, excessive weight loss in feline patients with CKD can lower survival rate. 10 Given high rates of both obesity and CKD in cats, it is inevitable that clinicians must weigh the relative risks and benefits of a weight reduction program in certain patients. The following steps are recommended: Perform a BCS on every patient at every visit and review the diet history. This reveals trends over time, both before and after CKD diagnosis. If the patient is 30% or more above ideal body weight, institute a judicious weight-loss program. If the patient is only mildly overweight (e.g., 6 or 6.5 on a 9-point BCS scale), feeding for stability vs. weight loss is preferable. When instituting a weight-loss program, restrict calories but do not restrict protein to avoid loss of lean muscle mass. Switching to a protein-restricted, energy-dense diet in the early stages of CKD is especially problematic because it can lead to concurrent body fat gain/muscle loss.

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