Page 369 - Small Animal Clinical Nutrition 5th Edition

378 Small Animal Clinical Nutrition

tein to cats. Furthermore, dietary protein excess may increase
Box 20-1. The Emerging Role of Omega-3 proteinuria and the progression of subclinical renal disease
VetBooks.ir Fatty Acids in Feline Nutrition. (Adams et al, 1994; Brown et al, 1997; Ross, 1992). Similar to

Fatty acids of the omega-3 (n-3) series (linolenic acid, 18:3n-3) findings in people and dogs, the role of protein in the progres-
sion of renal disease in cats is controversial. There is, however,
are probably required in the food of all animals. However, stud-
ies establishing requirements for omega-3 fatty acids in adult strong (Grade 1, [See Chapter 2]) evidence to support the rec-
cats have not been performed. Cats would normally consume ommendation to feed a veterinary therapeutic food designed
omega-3 fatty acids when eating the neural tissues of their prey. for kidney disease to cats with serum creatinine concentrations
The role of omega-3 fatty acids in companion animal medicine in excess of 2 mg/dl (stage mid-II through IV chronic kidney
has focused mostly on their pharmacologic-like properties and disease [CKD]) (Polzin et al, 2008; Ross et al, 2006; Elliot et
ability to modulate the immune response and inflammation al, 2000).The point being that, among other things, these foods
associated with dermatitis, arthritis, cancer and obesity. are typically lower in protein.
Although these effects may benefit some animals, untoward Although cats can be fed vegetable-based foods, most pro-
effects are possible. In one study, cats developed increased tein in the food should be derived from animal tissues. The
bleeding times and decreased platelet function when fed foods amino acid profile of most animal tissues better reflects the
supplemented with high levels of omega-3 fatty acids. However, nutritional requirements of cats. Moist products should list ani-
no adverse effects were found in similar studies. The current
understanding of omega-3 fatty acid metabolism in cats is lim- mal-based ingredients within the first two ingredients (exclud-
ited; thus, aggressive omega-3 fatty acid supplementation ing water), whereas dry products should list animal-based
should be used judiciously. The recommended dry matter ingredients in the first three ingredients. The recommended
allowance for omega-3 fatty acids in foods for healthy adult cats DM protein allowance for both normal weight and
is 0.01% (total eicosapentaenoic and docosahexaenoic acids). inactive/obese-prone young adult cats is 30 to 45%. Current
AAFCO allowances for taurine are appropriate for adult cats
The Bibliography for Box 20-1 can be found at (2007).Foods that have AAFCO label statements acknowledg-
www.markmorris.org. ing that a food is appropriate for adult maintenance should pro-
vide adequate amounts. Therefore, taurine, although a very
important nutrient for cats, is considered an “other” nutritional
Clinical evidence and field trials have demonstrated a reduction factor and is discussed under that heading below.
in the frequency of hairball vomiting with fiber supplementa-
tion (Hoffman and Tetrick, 2003; Dann et al, 2004). Phosphorus
Dietary phosphorus levels of 0.5 to 0.8% DM are recommend-
Protein ed for young adult cats. The minimum recommended
The protein requirements of adult cats have generally been allowance for phosphorus in foods for adult cats is 0.26% DM
established using experimental foods containing essential (NRC, 2006). Deficiencies of phosphorus are rare in cats fed
amino acids at or above the minimum requirement for growth. commercial foods. Phosphorus excess appears to be of greater
From these studies, the National Research Council (2006) sug- concern. Dietary phosphorus is a key nutrient in the manage-
gested the minimum protein requirement for adult cats is 16% ment of two common feline diseases: struvite-mediated
and the minimum recommended allowance is 20% (DM, food FLUTD and CKD. The mineral constituents of struvite are
energy content of 4 kcal/g [16.7 kJ/g]). Commercial foods pre- magnesium, ammonium and phosphate. Although the primary
pared from natural ingredients and processed may have lower objectives for preventing FLUTD due to struvite precipitates
protein digestibility than the experimental foods used to estab- are to increase urine volume, reduce urinary pH and, to a less-
lish these minimums.To provide a margin of safety and account er extent, restrict dietary magnesium, limiting dietary phospho-
for differences in protein quality, the Association of American rus may be beneficial (Chapter 46). The kidneys excrete excess
Feed Control Officials (AAFCO) has suggested a minimum dietary phosphorus. The risk of clinically apparent struvite
dietary protein level of 26% DM for adult maintenance (2007). crystalluria and urolithiasis is highest in cats from two to five
Protein and amino acid requirements vary with the energy con- years of age. Controlling phosphorus intake in combination
tent of a food. The minimum protein allowance suggested by with appropriate reductions in dietary magnesium concentra-
AAFCO is based on foods containing 4.0 kcal/g (16.7 kJ/g) tions and urinary pH, and increasing water intake, if possible,
DM and should be corrected for foods with energy densities should help reduce the risk of struvite-associated FLUTD in
greater than 4.5 kcal/g (18.8 kJ/g). (See Chapter 1 for the cor- cats of this age group.
rection method.) Excess dietary phosphorus is not considered a cause of renal
Meeting the minimum protein needs of cats is critical damage but may accelerate the progression of renal disease
because they have minimal capacity to adapt to low levels of towards failure and death (Ross et al, 1982). High levels of
dietary protein. Protein in excess of the requirement is rapidly dietary phosphorus (1.2 to 1.8% DM) reduce creatinine clear-
catabolized and used to provide energy and maintain blood glu- ance values and possibly reduce renal function in young, healthy
cose levels. Any excess energy will be stored as fat; therefore, cats (Pastoor et al, 1995). Excess phosphorus should be avoid-
there appears to be little benefit to feeding large excesses of pro- ed in the early nutritional management of renal disease in cats