Processed pet foods
I read the recent review article “Current knowledge about the risks and benefits of raw meat–based diets for dogs and cats”1 with interest. The authors provided compelling data, but I believe the article did not provide a balanced view of the potential benefits associated with feeding raw meat–based diets or adequately address potential dangers associated with processed pet foods.
In the article, for example, concerns about potentially carcinogenic heterocyclic amines in processed diets are confined to a single short paragraph. Including this paragraph in the section “Effects of Cooking on Digestibility,” I believe, inadvertently diminishes the importance of this topic. Furthermore, there is additional published research suggesting that these compounds may be a concern. For example, a 2003 study2 found that 24 of 25 commercial pet foods studied gave a positive mutagenic response when examined by use of the Ames test for mutagenic potential, and the authors concluded, “From these findings it is hypothesized that there is a connection between dietary heterocyclic amines and cancer in animals consuming these foods.”2 Similarly, a 2012 study3 found the heterocyclic amine 2-amino-1-methyl-6-phenylimidazo[4,5-b] pyridine (PhIP) in the fur of 14 of 16 healthy dogs consuming various brands of commercial pet foods. Those authors concluded, “A potential role for PhIP in the etiology of canine cancer should be considered.”3
Other toxins that are documented to occur in processed pet foods include pentobarbital, polybrominated diphenyl ethers (flame retardants that are linked to liver, thyroid, and neurodevelopmental toxicoses), and bisphenol A (an endocrine disruptor).
Whole foods (foods that are not heat processed) contain thousands of bioactive compounds, at least some of which may be as critical for health as vitamins and minerals4 but whose concentrations are reduced by processing. Evidence in favor of the health benefits of whole foods over processed foods has been published.5
In their review, Freeman et al1 state that “both cats and dogs are able to digest and metabolize many nutrients provided from plant-based ingredients.” However, this does not prove that such foods are healthy for them, nor does it demonstrate that cats and dogs can thrive on diets with high starch contents.
I contend that dogs and cats have not evolved away from their wild ancestors enough to profit from starch-rich commercial diets. Whereas insulin is the only hormone that lowers blood glucose concentration, 8 hormones (adrenalin, corticosteroids, glucagon, growth hormone, vasopressin, melanocyte-stimulating hormone, thyroid-stimulating hormone, and norepinephrine) increase it. This fact led one animal nutritionist to state that “keeping blood sugar held up to the proper and necessary level would appear to have been a much larger concern than keeping blood sugar down to the proper level.”6 Dog and cat biology has been shaped by millions of years of natural selection in an environment that provided almost exclusively low-starch diets, and I believe that such diets are still best.
Doug Knueven, dvm
Beaver Animal Clinic Beaver, Pa
1. Freeman LM, Chandler ML, Hamper BA, et al. Current knowledge about the risks and benefits of raw meat-based diets for dogs and cats. J Am Vet Med Assoc 2013; 243: 1549–1558.
2. Knize MG, Salmon CP, Felton JS. Mutagenic activity and heterocyclic amine carcinogens in commercial pet foods. Mutat Res 2003; 539: 195–201.
3. Gu D, Neuman ZL, Modiano JF. et al. Biomonitoring the cooked meat carcinogen 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine in canine fur. J Agric Food Chem 2012; 60: 9371–9375.
4. Jacobs DR Jr, Tapsell LC. Food, not nutrients, is the fundamental unit in nutrition. Nutr Rev 2007; 65: 439–450.
5. Omenn GS, Goodman GE, Thornquist MD, et al. Risk factors for lung cancer and for intervention effects in CARET, the Beta-Carotene and Retinol Efficacy Trial. J Natl Cancer Inst 1996; 88: 1550–1559.
6. Patton R. Ruined by excess, perfected by lack: the paradox of pet nutrition. Nottingham, England: Nottingham University Press, 2011.
Translating one health into practice
One health emphasizes the concept that human, animal, and environmental health are linked and interdependent. The concept is endorsed by numerous professional societies and organizations, but translating one health into practice has proven challenging. Recently, however, we were involved in an incident illustrating the practical value of a one health approach.
On August 2, 2012, a beaver attacked and bit a park visitor swimming in the Delaware River at the Delaware Water Gap National Recreation Area. The beaver was captured and killed during the encounter, and park authorities were notified. Park authorities contacted wildlife veterinarians from the National Park Service (NPS), who engaged members of the NPS's One Health Network to assist with the response. Because the park is located in both Pennsylvania and New Jersey and the victim was a resident of New York State, public health veterinarians in all three states were contacted and informed of the incident.
The beaver was submitted to the New York State Rabies Laboratory for testing because of the laboratory's proximity to the park and the availability of rapid diagnostic tests. The beaver tested positive for rabies virus on August 3, and the visitor was referred to a hospital for postexposure prophylaxis that same day.
Because the incident occurred in a rabies-endemic area with a high visitation rate, messages were posted in the park to inform the public of potential health risks. Park employees were instructed to increase their surveillance of wildlife and were provided information about personal protection and proper procedures if additional suspect animals were encountered. A risk assessment of the beaver lodge and surrounding areas was made in consultation with biologists and rabies experts at the CDC.
Soon after the beaver tested positive for rabies, a press release was distributed to state and local media by the NPS in cooperation with state and local officials. The entire investigation, response, and final press release were completed within 36 hours after the incident.
In the response to this incident, the combined efforts of public health, wildlife health, occupational health, resource management, and communications experts ensured that the health concerns of humans, wildlife, and the environment were addressed in concert, without compromising the perspectives of any single discipline. The proactive release of information may have prevented misinformation or undue public fear, while educating the public about the potential danger of rabid animals in the area and what to do should an encounter occur, thus reducing the risk of additional exposures and adverse outcomes. Input from rabies experts prevented unnecessary extermination of the beaver colony, benefiting wildlife as well. Preexisting interdisciplinary partnerships and networks improved the response, allowing for effective communication and flexibility.
The best means for translating one health into practice will differ from agency to agency, but the foundation should always include building interprofessional relationships and trust. The ability to tap into broad expertise quickly and efficiently allows a more synergistic response to issues affecting the health of all species.
Danielle E. Buttke, dvm, phd, mph
Kevin Castle, dvm, ms
Margaret Wild, dvm, phd
Wildlife Health Branch National Park Service Fort Collins, Colo
David Wong, md
Charles Higgins, ms
Office of Public Health National Park Service Washington, DC
Larry Hilaire
Delaware Water Gap National Recreation Area National Park Service Milford, Pa
Faye Sorhage, vmd, mph
Infectious and Zoonotic Disease Program New Jersey Department of Health Trenton, NJ
Bryan Cherry, vmd, phd
Surveillance Unit Bureau of Communicable Disease Control New York State Department of Health Albany, NY
