Pet Food—Ensuring Health in the Kennel

There have been nearly 1,300 voluntary recalls of pet foods since the melamine crisis in 2007. Pet food safety issues are quite similar to those affecting the general food supply—microbial contamination and adulteration. Critical in the management of public health is that some outbreaks of infection are associated with contaminated pet foods (Morbidity and Mortality Weekly Report, 2008).

According to The Humane Society (2009), there are about 77.5 million dogs and 93.6 million cats owned in the United States. More than one-third of American households have either one dog or one cat, which explains the $45 billion U.S. pet food market (2007).

Unlike human foods, pet foods are designed to be balanced and complete for the species. These sole sources of nutrition are under the regulatory authority of the Center for Veterinary Medicine, part of the U.S. Food and Drug Administration. Regulations for product labeling and ingredients are similar to those for human foods. However, the real challenge is that each state has its own laws governing animal feed, including requirements for manufacturer and product registration, licensure, and pre-market approval. Interestingly, while the Association of American Feed Control Officials (AAFCO) does not have any regulatory authority, the annual AAFCO publication provides the foundation of all pet food regulations. In addition, AAFCO also provides guidelines for assessing product safety and efficacy of pet foods, their ingredients, and potential health claims.

Food products for our canine and feline friends often feature health claims similar to those for humans. This development is complicated by the often unique metabolic differences between species and their respective health issues. Yet, some human health issues also affect dogs and cats. For example, obesity affects about 25% of dogs and cats in the U.S., and the prevalence of this malady increases with age (Courcier et al., 2010). On the other hand, sodium is rarely an issue in healthy animals. Dietary fiber, which is under consumed by humans, is not classified as an essential nutrient for dogs and cats. Yet, soluble and insoluble dietary fiber in dog and cat foods can have effects on gastrointestinal transit and health similar to those reported in humans.

The popularity and importance of omega-3 fatty acids in human foods has gained momentum in dog and cat foods. However, our current understanding of the fatty acid metabolism in dogs and cats suggests they may meet the apparent docosahexaenoic acid (DHA) needs from the upstream alphalinolenic acid (ALA) precursor. In addition, high-fat diets (~60% metabolic energy) are well tolerated by dogs and cats without adverse health effects (National Research Council, 2006). On the other hand, an increased intake of polyunsaturated fatty acids by beagles may modulate classic cardiovascular risk factors, such as plasma HDL and triglycerides and affect the dog’s immune system through down regulating, as appropriate, potential chronic inflammatory intermediates, such as some prostaglandins (Wander et al., 1997).

Since the launch of the human microbiome project in 1997, many investigators have concluded that an investment in maintaining gut health may be critical in understanding several diseases and their respective inflammatory components (National Institutes of Health Human Microbiome Project Working Group, 2009). For example, obesity and the development of metabolic syndrome may reflect an increased production of bacterial lipopolysaccharide following the consumption of a high-fat diet. Even inflammatory responses associated with cardiovascular disease may be modulated by gut microbes. When it comes to the canine and feline microbial profile and their respective microbiome, there is a dearth of information.

Beta-glucan may provide health benefits in companion animals. Among those benefits is a more robust immune system as demonstrated in beagles challenged by fungal infections (Rop et al., 2009). Although there are limited data, it appears that dietary supplements, such as garlic and grape seed extract, may improve some immune health biomarkers in dogs and cats. However, most functional information for dietary supplements directed to dogs and cats is extrapolated from other species, particularly humans.

The assessment of safety and efficacy of pet foods and dietary supplements for dogs and cats is challenging and represents new opportunities for food scientists and animal nutritionists, as well as veterinarians. The diverse metabolic differences among species and throughout their life stages, coupled with state-by-state regulatory hurdles, represent challenges and opportunities for the growing and competitive pet food market. After all, humans love their four-legged companions. I know … I have two dogs and a cat… all rescued from the local Humane Society facility.

References cited in this article are available from the author.

by  Roger Clemens, Dr.P.H.,
Contributing Editor 
Scientific Advisor, ETHorn, La Mirada, Calif. 
[email protected]