Wilson SA, Villaverde C, et al. Evaluation of the nutritional adequacy of recipes for home-prepared maintenance diets for cats. J Am Vet Med Assoc 2019;254:1172-1179.
The popularity of homemade diets for pets has burgeoned in the last decade, as an increasingly health-conscious and foodist culture in the first world extends its expanding interest in dietary therapy and its potential role in optimizing human health and treating disease, to companion animals. An information explosion largely centered on the Internet and online social media, as well as in print media, has allowed pet owners to seek dietary information and recipes for home-prepared foods from a wide array of channels other than the family veterinarian, and has also led to a search for alternatives to commercial pet foods by a substantial number of pet owners.
Cats in particular, as obligate carnivores who cannot, like many other species, synthesize de novo a number of essential nutrients and must instead acquire them from their diet, have specialized dietary needs. This paper outlines the findings of the first systematic study of home-prepared diets for adult cats published in books and online sources, involving 114 recipes which were each analyzed qualitatively and quantitatively. The nutritional profiles of these recipes were compared with the recommended allowances (RAs) of essential nutrients for adult cats as published by the National Research Council (NRC). Some of the recipes evaluated were authored by veterinarians and some by non-veterinarians. Only those recipes not labeled for medical conditions, gestation, lactation, or growth, use as a treat, or for supplemental or intermittent feeding, were analyzed in the study. Computer software was used to compare the nutrient profiles of the recipes with the NRC RAs.
The source of 48 recipes was the Internet, and books provided the other 66. Ten of the recipes did not provide enough information for computerized nutritional analysis. All but one of the 94 recipes that could be analyzed using computer software had issues with clarity of directions in one or more areas: specification of amounts and types of ingredients or supplements, preparation instructions, and/or feeding directions.
None of the 94 recipes analyzed by computer met all NRC RAs for adult cats, and those designed by non-veterinarians (including anonymous sources) contained more nutrient levels that were lower than the NRC RAs than those created by veterinarians. Potentially toxic ingredients, including garlic, onions, and leeks, were found in 8/114 recipes. Over half of the recipes (50/94) contained inadequate taurine levels. Based on the NRC RAs for adult cats, most recipes (72/94) were choline-deficient; other notable deficiencies found included iron (72/94), thiamine (59/94), zinc (58/94), manganese (54/94), vitamin E (54/94), and copper (43/94). Some of the recipes also contained nutrient concentrations that exceeded the safe upper limit for specific ingredients established by the NRC.
Almost all of the recipes met the NRC RAs for all essential amino acids except for taurine, which is crucial in the prevention of diet-associated dilated cardiomyopathy in cats. No warnings regarding food safety concerns associated with the use of raw animal products were provided with most of the recipes involving the use of these foodstuffs.
The authors state that none of the home-prepared diets they evaluated were nutritionally adequate for long-term feeding of adult cats. Another concern associated with the use of such diets is “ingredient drift,” wherein owners may modify recipes on their own, or substitute or omit ingredients included in the original recipe, which can further increase the risk of nutritional inadequacy and/or imbalance associated with the feeding of a home-prepared diet. The advice of a board-certified veterinary nutritionist in evaluating and producing a recipe for home-prepared food, and providing guidelines for ingredient selection, preparation, and feeding, will substantially reduce the risk of development of health problems associated with long-term feeding of an unbalanced diet, and is strongly recommended. Several veterinary teaching hospitals and private concerns offer online consulting services provided by board-certified veterinary nutritionists, who can create customized recipes for individual patients in any healthy life stage as well as for animals with disease conditions. [PJS]
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