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 25-28 September, 2018 | Singapore
M. Scherk1
1Dip ABVP (Feline Practice), Vancouver, Canada INTRODUCTION
Cats with chronic kidney disease (CKD) frequently lose weight or have low body condition score (BCS). Although not yet shown in prospective studies, preservation of body weight and lean body mass (LBM) may enhance survival and quality of life in aging cats and those with CKD. Indeed, some loss of weight is part of normal aging, and is not caused by apparent illness. Nutrition offers the possibility to improve longevity as well as quality of life (QoL).
Sarcopenia, the age-related loss of lean body mass (LBM), is a gradual process: initially it is unapparent because increases in body fat persist, and may even cause increases in body weight. However, the loss of LBM has profound effects on survival. Studies have identified decreased survival associated with thin body condition.1-3
In one study of cats with large cell lymphoma, those
that lost > 5% body weight during treatment had a significantly shorter survival time than those who were able to maintain their weight. 4 Patients with other cancers that had a slightly increased or ideal body condition score (BCS) survived up to six times longer than underweight cats.5 In chronic kidney disease (CKD), cats with higher BCS lived longer than those with lower BCS.6 Similarly, cats with heart failure in ideal or slightly greater BCS fared better compared to cats that were underweight or obese.7]
Is it possible to prevent cats with CKD from losing muscle and body condition? Is it possible to prevent cats with CKD from losing muscle and body condition? Several studies have shown a decreased ability to digest fat8,9, protein8,10, and micronutrients11 in otherwise healthy aging cats. Because of this, a high energy, highly digestible diet with an increased protein content may be appropriate. Studies in healthy cats suggest that 5 – 6g protein/kg body weight is needed to maintain or enhance LBM.12-13 One small, unpublished study in middle-aged cats with mild CKD showed they could maintain LBM over 30 weeks when fed only 6.5g protein/100 kcal.14 However, it is unclear what the actual protein intake was, as no data on actual food intake or body weight was included (i.e., protein calories ingested). If cats are eating only small amounts of food, a higher percentage of calories from protein may be needed to meet their needs.
Old cats need protein. The majority of cats with CKD live
a long time. Given the importance of protein in cats, how do we optimize the benefits of a renal diet but correct or prevent further muscle wasting?
Step 1: Evaluate
Just as every cat is different, the needs of different cats with CKD may differ. It is important to start by finding
out exactly what, (foods, treats, supplements), and how much, a patient is eating. A simple diet history form can be found at: Evaluating body condition entails not just assigning a body condition score (BCS, Figure 1), but also getting a weight at every visit. Both body weight and BCS are subjective ways to evaluate caloric adequacy: weight reflects the current state and BCS, gives a longer term perspective.
Figure 1. Body Condition Score (from nutrition-toolkit => Body Condition Score Cart for Cats .pdf)
Calculating the percent weight change is an easy
way to follow trends and get a better idea of weight relative to size. This important measure helps alert both the practitioner and the client to insipient (or blatant) physiologic alterations.
Loss of muscle can occur without fat loss or a decrease in BCS and individuals can retain an obese or overweight BCS yet be under muscled. Muscle condition scoring (MCS, Figure 2, Table 1) is a subjective way to evaluate LBM. Therefore, both subjective BCS and MCS should be performed in all cats, to evaluate fat mass and lean mass independently of each other.17 When clients participate in determining BCS, it is more meaningful to them. Similarly, they can be taught to assess muscle condition.

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