Dog owners who cook food for their pets at home may be putting a lot of love into the recipes, but they are likely not adding enough nutritional value, according to researchers from the University of California, Davis, School of Veterinary Medicine.

The researchers analyzed 200 recipes for homemade dog food to determine how many of them meet established nutritional standards. According to the results published in the June issue of the Journal of the American Veterinary Medical Association, very few of the recipes were nutritionally complete.

"The results of this study, however, indicate that most available recipes for healthy dogs, even those published in books by veterinarians, do not provide essential nutrients in the quantities required by the dog," said Jennifer Larsen, assistant professor of clinical nutrition at the William R. Pritchard Veterinary Medical Teaching Hospital at UC Davis and lead author on the study. "It is extremely difficult for the average pet owner - or even veterinarians - to come up with balanced recipes to create appropriate meals that are safe for long-term use."

Most recipes have nutritional deficiencies

For the study, researchers analyzed 200 recipes from 34 sources including veterinary textbooks, websites, and pet care books. They used a computer-based program to evaluate recipes for the nutritional content in the food as well as the specificity of the instructions, UC Davis said. The researchers' findings included:

• Out of 200 recipes studied, only nine contained essential nutrients in concentrations that met the minimum standards for adult dogs established by the Association of American Feed Control Officials. Eight of the nine recipes were written by veterinarians.
• Five recipes - all written by veterinarians - featured essential nutrient concentrations that met the National Research Council's Minimum Requirements for adult dogs.
• Only four recipes were written by board-certified veterinary nutritionists, and all of those recipes had acceptable nutrient profiles for adult dogs.

According to Larsen, 95 percent of the recipes produced food that lacked the necessary levels of at least one essential nutrient such as choline, vitamin D, zinc, or vitamin E. Eighty-three percent of the recipes lacked multiple nutrients, she said.

Vague or incomplete instructions for majority of recipes

In addition to the nutritional deficiencies discovered, researchers also determined that 92 percent of the recipes had vague or incomplete instructions. The faulty instructions left pet owners to make at least one guess regarding ingredients, preparation methods, or the use of supplement-type products, UC Davis reported. 

Researchers also reported that 85 percent of the recipes did not supply owners with calorie information or specify the size of dog for which the recipe was meant.

Researchers' recommendations regarding homemade food

According to Larsen, preparing homemade pet food isn't a bad idea for pet owners - she just believes her group's research shows that it should be done under the guidance of experts.

"Homemade food is a great option for many pets, but we recommend that owners avoid general recipes from books and the Internet and instead consult with a board-certified veterinary nutritionist," she said. "These specialists have advanced training in nutrition to help formulate customized and nutritionally appropriate recipes."