Pros and cons of raw food diets (Proceedings)

August 1, 2011
Kate KuKanich, DVM, PhD, DACVIM

When a new pet is acquired, numerous factors become part of the owner's decision of which diet to select. A pet owner may consider feeding advice from family, friends, the pet's breeder, trainer, or their local veterinarian. The internet has also become a large available source of information for pet owners regarding feeding options and other health issues for pets.

When a new pet is acquired, numerous factors become part of the owner's decision of which diet to select. A pet owner may consider feeding advice from family, friends, the pet's breeder, trainer, or their local veterinarian. The internet has also become a large available source of information for pet owners regarding feeding options and other health issues for pets. Pet owners can find information on a full spectrum of dietary options online, from traditional commercial diets to non-traditional homemade diets. Raw food diets especially have gained popularity because of various perceived holistic and natural benefits. It is important for veterinarians to understand the rationale behind why owners choose to feed raw food diets, the differences between various diets, and safety concerns involved, so they can provide solid and trustworthy advice to clients.

Rationale behind raw food diets

Raw food diets are touted for being more natural, healthier, and more economical than commercial cooked dry or canned pet food. A common cited rationale is that dogs and cats are carnivores and evolved eating raw and natural foods, while the processing of foods may destroy or alter nutrients. Proposed benefits of raw food diets include: improved immune function, improved coat appearance, preventing dental disease from chewing on bones, eliminating bad breath, improving body odor and fecal odor, minimizing risk of gastric dilatation and volvulus, preventing cardiac disease, increasing energy levels, controlling growth levels of puppies and kittens, optimizing weight management, decreasing risk of pancreatitis, promoting longer lifespan, improving reproductive success, reducing arthritis, and decreasing veterinary costs (due to fewer allergies and other diseases). However, to the author's knowledge, there is no evidence-based research to support any of these health claims. In some cultures or religions, homemade diets with raw foods may have a spiritual significance. Raw food diets may also be in favor because they give owners control of exactly what their pets are eating, allowing hand-picking of produce and meat, and the option to choose local or home-grown foods.

Types of raw diets

There is no standardized raw diet; instead there are many such diets that fit within two general categories: homemade raw recipes and commercially prepared raw diets. Recipes for homemade diets can be found in numerous books and websites. The strictest of raw diet feeders are considered purists who feed only raw meat, bones, and eggs, but no fruit, vegetables, or grains; these diets rarely include supplements to make them balanced or complete. Many raw diet proponents believe that dogs and cats are not capable of digesting grains, and that diets containing grains have led to allergic and digestive diseases in companion animals. There are several well-known homemade raw diets, including the BARF homemade diet (standing for bones and raw food), the Ultimate diet, and the Volhard diet. In many diets each meal is not meant to be balanced; however, over time the diets aspire to provide balanced nutrition. Many pet owners have amended these popular raw food diets to create their own recipes with or without additional supplements. For all raw diets, meat can be purchased in bulk at local butcher shops, co-ops, and grocers. Commercially prepared raw food diets are typically sold frozen, although refrigerated diets are also available. One example is Dr. Billinghurst's commercial BARF diet marketed as frozen patties that are to be thawed and fed raw. Most commercial diets contain meat, bones, produce, and supplements to make a complete and balanced diet. The act of freezing is suggested to kill most bacterial contamination; however many bacteria are known to survive the freezing process. Although commercial diets may be a more convenient way to feed raw, they may also be more expensive than homemade diets and are considered "too processed" for many purist raw diet proponents. Due to the large variety of raw diet options, it is important for veterinarians to review with clients homemade recipes or commercial labels from raw diets fed to their patients, so that they can make recommendations regarding any safety concerns or need for supplementation.

Safety concerns with raw diets

Although raw diets may be perceived as very natural, there are several health concerns to consider with these types of diets. Bacterial and parasitic contamination is one potential problem which has been researched yet remains a point of contention. Proponents of raw food diets explain that dogs are scavengers and are able to tolerate a certain amount of bacteria that they may encounter in the routine raw diets without becoming ill; however other raw food supporters suggest not feeding pork, venison, or rabbit, because these animals may have parasites that companion animals cannot tolerate. Concern of bacterial contamination is not limited to raw diets. In recent years, there have been multiple recalls of commercial (cooked) pet foods and treats that have been contaminated with Salmonella due to cross-contamination at manufacturing plants. While commercial food is regulated by the FDA and closely monitored for contamination, components of raw diets may not be subjected to regulation. Weese et al evaluated 25 commercial canine and feline raw diets and isolated coliforms from all diets, including E. coli (64%) and Salmonella (20%), as well as Clostridium perfringens (20%), and Staphylococcus aureus (4%); Campylobacter was not isolated from any of the tested diets. Salmonella is commonly isolated from raw meat intended for canine consumption, found in 80% of BARF diet samples and 30% of canine fecal samples in one study (Joffe 2002), and isolated from 45% (50/112) commercial raw meat used in Greyhound diets in a second study (Chengappa 1993). Furthermore, feeding raw meat contaminated with Salmonella has been directly associated with outbreak of gastrointestinal disease (Morley 2006) as well as septicemia (Stiver 2003). Campylobacter is also a concern because of recognized prevalence in raw poultry and eggs, which are common components of raw diets for companion animals. Other bacteria of concern include: Yersinia enterocolitica, Listeria, Mycobacterium, and Francisella tularensis (LeJune 2001). Potential parasites that may contaminate raw diets may include Diphyllobothrium latum and Nanophyetus salmincola from fish, Toxoplasma gondii, Sarcocystis spp, Neospora caninum, and Trichinella spiralis from infected meat, and Cryptosporidium from meat contaminated with infected intestinal material or feces. While laws are in place to minimize contamination of meat intended for human consumption, these laws do not protect meat intended for pet consumption. Therefore, owners who elect to feed raw meat and eggs should be careful to purchase only products of quality acceptable for human consumption from a clean and trusted source.

A second health concern to consider with raw diets is the possibility of fractured teeth, gastrointestinal obstruction, or GI perforation from ingestion of bones. Raw diet proponents recommend feeding raw vs. cooked bones, as raw bones are softer, easier to digest, and less likely to cause gastrointestinal problems. Even raw bones are hard enough to cause fractured teeth. Gastrointestinal obstruction or perforations are considered by raw diet proponents to be extremely rare, while processed kibble is considered just as likely to cause obstruction. The actual incidence of GI obstruction or perforation from eating raw or cooked bones (or kibble) is unknown. Despite a high proportion of reported esophageal foreign bodies being bone (48/65 in a review by Moore, 2001), most studies do not report whether obstructing bones were cooked or raw. If owners wish to feed bones as part of a raw diet, the risk of obstruction and perforation should be discussed. Options to minimize this risk could include supervision to allow chewing on large bones but prevent ingestion by timely removal, or only feeding bones that have been ground into very small pieces.

Finally, there is much debate about the overall nutritional balance of raw food diets. All pet owners want their animals to be as healthy as possible, but the nutritional needs of dogs and cats are complex. While some raw food diets may be balanced over time (although each meal may not be balanced and complete), others may have nutritional imbalances that could lead to malnutrition, secondary nutritional hyperparathyroidism, dermatoses, or other medical issues. The bottom line is that while it is recommended that all pet diets meet the Association of American Feed Control Officials (AAFCO) profiles for nutritional standards as well as undergo feeding trials designed by AAFCO, most raw diets have not undergone such testing or research trials. A study by Freeman and Michel (JAVMA 2001) performed a nutritional analysis of 5 raw diets (3 homemade and 2 commercial) and found that all had nutrient deficiencies or excesses "that could cause serious health problems when used in a long-term feeding program." While this was a limited study, research to support the use of raw food diets for specific health claims or as an overall maintenance diet is lacking.

Conclusions and safety suggestions

Inquiring about the reason why a pet owner is considering or feeding a raw food diet provides an opportunity for open discussion and may help a veterinarian suggest alternatives that both the veterinarian and client are comfortable with for feeding the pet. For example, if a pet owner would like their pet to have the natural benefits of fresh fruits and vegetables, proper selection can be discussed with their veterinarian (ie no raisins or grapes) and this produce can be added to a pet's meal, while keeping a (cooked) commercial diet as the mainstay for nutrition and safety. Properly cooked meat and eggs can also be added as a treat for pets. If a (cooked) commercial diet is not included for maintenance, and a homemade recipe comprises the majority or all of the pet's diet, then it is wise to consult with a boarded veterinary nutritionist to be sure that the recipe is providing a complete and balanced diet for the pet. Although there are no government standards for defining "human grade," clients who elect homemade recipes should be encouraged to feed only food they deem appropriate for human consumption. Commonsense safety precautions should be taken in the kitchen of all cooks to minimize risk of bacterial cross-contamination, especially of raw meat and eggs. This concern is magnified when groups of raw food supporters join together to make large "batches" of a raw diet in bulk and then divide it between families. Hands should be washed frequently, and bowls, utensils, and countertops cleaned thoroughly with bleach. Proper storage of raw food should also be emphasized; most refrigerated fresh or thawed meat products should be used within 3 days. Any uneaten raw food should be removed from pet bowls and properly disposed of as soon as the meal is over, and pet food bowls should be washed with hot soapy water daily. Children and people considered to be immunosuppressed should be discouraged from handling any pet food, especially raw diets.

Clients who choose to feed their pets raw diets have typically done much research on the potential benefits of these diets and are not interested in reverting to a more conventional feeding style. As veterinarians, we can help make certain that these clients are fully educated about the pros and cons of these diets, and focus on the need for safety precautions to ensure that both the pets and people within these households remain as healthy as possible.

Select references

Weese JS, Rousseau J, Arroyo L. Bacteriological evaluation of commercial canine and feline raw diets. Can Vet J 2005;46:513-6.

Joffe DJ, Schlesinger DP. Preliminary assessment of the risk of Salmonella infection in dogs fed raw chicken diets. Can Vet J 2002;43:441-2.

Chengappa MM, Staats J, Oberst RD, et al. Prevalence of Salmonella in raw meat used in diets of racing greyhounds. J Vet Diagn Invest 1993;5:372-.

Morley PS, Strohmeyer RA, Tankson JD, et al. Evaluation of the association between feeding raw meat and Salmonella enterica infections at a Greyhound breeding facility. JAVMA 2006;228:1524-1532.

Stiver SL, Frazier KS, Mauel MJ, et al. Septicemic salmonellosis in two cats fed a raw diet. JAAHA 2003; 39:538-542.

LeJune JT, Hancock DD. Public health concerns associated with feeding raw meat diets to dogs. JAVMA 2001;219:1222-5.

Moore AH. Removal of oesophageal foreign bodies in dogs: use of the fluoroscopic method and outcome. J Small Anim Pract 2001;42:227-230.

Freeman LM, Michel KE. Evaluation of raw food diets for dogs. JAVMA 2001;218:705-9.