|Cooking Up Trouble|
PFI Monitor, Fall 2013 Issue
One myth about pets that has emerged in recent years is that homemade food is superior to commercial products. Numerous recipes can be found on the Internet for homemade pet food, and several books have been published touting the benefits of their recipes for dog and cat diets. The reality is that the actual benefits of such concoctions do not measure up to the rhetoric.
"Many pet owners think a good way to show love to their pets is to cook for them, just like they do for their human family. What they don’t realize is they could be serving up some real nutrition issues along the way because many recipes for homemade pet food do not provide all the nutrients their pets need to stay healthy,” said Dr. Angele Thompson, president of Thompson Pet Tech.
Most pet food products on the market are designed to provide total nutrition for pets. Such complete and balanced products contain the right balance of protein, fat, fiber and carbohydrates. Complete and balanced products provide between 42 and 48 required nutrients, including specific vitamins, minerals, fatty acids and amino acids. "Balancing all of those nutrients is complex, but that work is the day in and day out responsibility of commercial pet food manufacturers” said Dr. Thompson. Pet food product recipes are tested according to very specific procedures to confirm they provide sufficient nutrition before a product is ever sold. In contrast, many recipes for homemade pet food have not been tested according to the same procedures, so there is little assurance homemade cat or dog food provides adequate nutrition for a long, healthy life.
A recent study conducted by a team of researchers at the University of California, Davis, School of Veterinary Medicine analyzed 200 different recipes for home-prepared dog foods. Recipes were selected from websites, veterinary textbooks and pet care books. The findings were startling: 95 percent of the recipes were deficient in least one essential nutrient, and 84 percent were lacking in multiple required nutrients.
Dr. Jennifer Larsen, a board-certified veterinary nutritionist and one of the veterinarians who conducted the study, explained the challenge of developing a diet for homemade dog food, "Formulation of a balanced recipe is a computer-driven process, since complex calculations are necessary to ensure appropriate amounts of each of 40+ essential nutrients are provided. It is difficult for the average pet owner — or even veterinarians — to do this without training and expertise in the various aspects of pet nutrition.” The study found that even recipes authored by veterinarians had significant problems with nutritional adequacy. However, although board certified veterinary nutritionists wrote only four of the recipes, all of these were found to be balanced.
When pets eat a diet that is short in a key nutrient, they do not consume all the nutrition they need to live a long, healthy life. Symptoms of inadequate diet might show up quickly if the vitamins are water soluble (e.g., B vitamins) or if the shortage is for amino acids or some minerals. If the deficient vitamin is fat-soluble (e.g, vitamin A, vitamin D, vitamin K), problems may not reveal themselves for weeks or months. Depending on the stage of life of the animal, the consequences of the deficiency may be more severe. Growing puppies and pregnant dogs are most vulnerable.
Health problems that could result from the nutrient deficiencies that were most commonly found among the recipes assessed in the study include skin problems (zinc), bone and joint problems (calcium), and weight loss and fat accumulation in liver (choline).
All recipes were evaluated using computer software designed to analyze pet food diets. The nutritional content of each diet was calculated based upon the nutrient profile of the individual ingredients. Once the total nutrient content was determined, it was compared against the minimum requirements and recommended allowances established by the National Research Council (NRC) as well as the nutrient profiles minimums and maximums for adult maintenance set by the Association of American Feed Control Officials. Later a number of diets were analyzed in a laboratory to confirm the accuracy of the calculated values.
Some of the homemade dog foods had so little of certain nutrients that they did not provide even half of the NRC’s recommended daily intake: 95.1% provided less than half the needed vitamin D, 55.1% provided less than half the needed zinc, 43.4% provided less than half the needed choline, and 39.2% provided less than half the needed vitamin E.
"This study shows that most recipes for homemade dog food do not provide proper nutrition for long, healthy lives. These are serious flaws, and these deficient recipes for homemade dog food should be withdrawn by their authors,” said Duane Ekedahl, president of PFI.
To complicate the situation, Larsen explained that a common practice of rotating between different homemade diets over time likely would not make up for the deficiencies because so many recipes shared the same deficiencies. "The article doesn’t point out the potential additional hazard for homemade diets of properly and repeatedly measuring each ingredient carefully to make a homemade diet,” commented Dr. Thompson. "Not many people can do that in their own kitchens.” In addition, many recipes provide vague instructions for ingredients or for preparation, leaving the pet owner to interpret what type of meat to use or which supplement product to buy, for example. This factor alone could result in homemade diets that vary significantly from the intended recipe and is yet another source of potential problems.
This recent study is not the first to evaluate homemade diets. In March 2012 Larsen published a study analyzing homemade diets for cats and dogs with chronic kidney disease (CKD). That study also found many problems with vague recipe components or instructions, and assumptions were needed to analyze every recipe. In addition, a large number of diets were short in one or more essential nutrients, especially protein and amino acids. Although some cases of CKD may require reductions in protein intake to help control clinical signs or help address protein loss through the kidneys, these patients should eat adequate amounts of protein. Other nutrients found in concentrations below the requirements included choline, selenium, zinc, and calcium. Interestingly, the median phosphorus concentration in the recipes was appropriately restricted for most pets with this disease. However, the significant problems with nutritional adequacy in these recipes cannot be overlooked, and this underscores the importance of consulting with a board certified veterinary nutritionist to formulate a customized homemade diet recipe when this is needed for an individual pet. For healthy pets, and for most ill pets, commercial diets are reliable, convenient, and balanced for their needs.
"Don’t take a chance with your pet’s health,” advised Ekedahl. "Feed a nutritionally appropriate commercial diet that will provide all the nutrients your pet needs while saving time for more enjoyable activities like playing or cuddling with your pet.”