Raw feeding is the practice of feeding domestic dogs, cats and other animals a diet primarily of uncooked meat, edible bones, and organs.
Supporters of raw feeding believe that the natural diet of raw meat, bones, and organs is superior nutritionally to highly processed commercial pet food. They mimic a similar diet for their domestic companion, as it is believed that a balanced raw diet has the benefits of giving the animal a healthier coat, cleaner teeth and breath, reduced stool volume and odor, and better overall health. They are commonly opposed to commercial pet foods, which they believe are detrimental to an animal's health. Opponents believe that the risk of nutritional imbalance, intestinal perforations and foodborne illnesses posed by the handling and feeding of raw meat and bones would outweigh any benefits. The assertion that raw feeding is inherently better because it is natural has also been criticized.
Few studies have been done to prove or disprove the numerous beneficial claims of a raw diet.
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Raw food proponent Dr Ian Billinghurst (owner of the registered trademark 'Barf Diet' and the BARF World Distributor Network) argues in his books that the dog has evolved over many million years on a natural raw diet and logically, this is the ideal food source. He claims that processed foods are "not what [the] dog was programmed to eat during its long process of evolution" and says that foods similar to those eaten by the dog's wild ancestors are more biologically appropriate.[1]
Proponents have also pointed at the practices of some modern zoos which feed their captive carnivores raw meat and bones or whole carcasses.[1][2] The curator of the Folsom City Zoo Sanctuary has said that "Common sense suggests that there is no more nutritious food we can offer to a carnivore than the entire carcass of their natural prey type." While raw feeding is generally well accepted in European zoos, it is a controversial topic within American zoos.[3] Concerns are similar to those expressed by opponents of raw feeding and includes dental impactions, airway obstructions, intestinal perforations, food contamination and social aggression. Benefits include better oral health, mental stimulation through processing of carcass (see Behavioral enrichment) and higher activity level. [4]
Critics have pointed out the flaws in associating "natural" with better[5] and Billinghurst himself warns against that stating "There are grave dangers that go along with the natural diet and natural conditions the ancestors or wild cousins of our dogs live with."[1] Katie Merwick, who runs an animal rescue sanctuary cautions against "making a fetish out of what animals eat in the wild"(paraphrased)[5]
The intense heat used to process commercial pet food destroys and reduces nutrients like vitamins, minerals, and enzymes.[6] Studies with rats showed that the digestibility of amino acids in cat food is changed significantly by heat processing.[7] Pet food manufacturers must supplement the food after heat processing to replace those nutrients. Most raw feeders believe that supplements have reduced nutritional value compared to the same nutrients in raw food and that possible nutrients not yet recognized as essential by nutritional science cannot be replaced. The same rationale is used by some to reject supplemented home cooked pet food. Most owners claim a distinct change in pets' general health once shifting towards a raw food source.
Commercial pet foods, dry foods in particular, often contain a large amount of grains, which proponents of grain-free food feel are inappropriate for dogs and cats. Because cats are obligate carnivores, it is believed that a switch to a predominantly meat based raw diet would be especially beneficial (as compared to a raw diet for dogs) due to cats' relative inability to digest grains. Studies comparing the source of protein in dry cat food concluded that the digestibility of meat-based protein is superior to corn-based protein.[8]
Veterinary surgeon and raw feeding proponent Tom Lonsdale states that food from dry or canned commercial kibble sticks to teeth and enables bacteria to proliferate, causing "sore gums, bad breath and bacterial poisons that affect the rest of the body". Lonsdale further states that dogs lack the necessary enzymes to digest grains and plant material and claims that grains cooked at high temperature can cause starch, proteins and fats to become "denatured or toxic in variable degrees." The poorly digested grain is said to support toxin-producing bacteria in the lower bowel which may eventually lead to "poisons pass[ing] through the bowel wall into blood circulation" creating further problems in other organs.[9]
Herbalist Juliette de Bairacli Levy is credited with starting the holistic pet care movement in the 1930s. In her books, she preached, amongst other things, that dogs require a natural diet of raw food.[10] Australian veterinary surgeon Ian Billinghurst, who published "Give Your Dog a Bone" in 1993 credited de Bairacli Levy's book as an inspiration.[11]
There are various differences in opinion within the raw feeding community. Issues include the question of whether dogs are omnivores or carnivores. Also, whether cats and dogs need plant material in their diet, and if so, the proportion of such material. The safety of whole bones is also a frequent topic of discussion. Recipes that are advocated range from those that include vegetables and grains, to a minimalist approach using only meat, bones, organ meat, and necessary supplements such as the Meat with Bone diet advocated by Michelle T. Bernard.[12]
The "BARF" diet, an acronym for Biologically Appropriate Raw Food or Bones And Raw Food was created by Billinghurst. A typical BARF diet is made up of 60-80% of raw meaty bones(RMB), that is bones with about 50% meat,[13](e.g. chicken neck, back and wings) and 20-40% of fruits and vegetables, offal, meat, eggs, or dairy foods.
This acronym was originally coined by Debra Tripp to mean "Born Again Raw Feeders". Debra later changed it to "Bones and Raw Food" after trying the diet on her own dogs. Debra met Dr. Billinghurst later at one of his seminars and he signed a copy of his book (Give Your Dog a Bone) thanking her for the BARF acronym.
The "Prey model" diet attempts to simulate the proportions of an actual prey animal in a pet's diet. Actual whole prey are used whenever possible, including whole rabbits, chickens, game hens and turkeys. Generally, the diet recommends 80% meat (including some 'meaty' organs such as heart), 10% bone and 10% organs (of which half is liver). Proponents of the whole prey model diet believe dogs and cats are both natural carnivores and therefore there is no nutritional or dietary need for anything other than meat, bones, and organs,.[14][15] The supporters of the prey model also focus on feeding meats from a wide variety of animals, and some add small amounts of vegetable matter.
Supplements are generally not used in a prey model diet although some followers do add fish oil to the diet to compensate for the reduced amount of omega-3 fatty acid in commercially raised grain-fed livestock.[16]
As raw diets can range from meticulously prepared and tested to diets composed of a variety of meats and butchers' scraps, the nutritional balance of a raw diet can vary greatly depending on the recipe. However, supporters of raw feeding believe that not every meal needs to be "complete and balanced", and that nutritional balance can be achieved over time by feeding a wide variety of meats, fats, bones and organs from several sources, such as chicken, turkey, lamb, cattle, pigs, fish, rabbits, etc., and even wild game. The general belief among the supporters of raw diets is that pets have no more complex nutritional requirements than humans, and that a variety of ingredients over time will provide the pets with a sufficiently balanced diet.
Many who oppose raw diets believe that the Association of American Feed Control Officials (AAFCO) standards that many commercial pet food comply with gives an assurance of quality that homemade food cannot give. One study that analyzed the nutritional content of three homemade diets (BARF, Ultimate and Volhard) and two commercial raw food diets (Steve's Real Food and Sojourner Farms) and compared it to the AAFCO standards, showed that nutritional imbalances occurred in multiple areas.[17] Three of the diets had abnormal calcium-to-phosphorus ratios which can lead to hyperparathyroidism and fibrous osteodystrophy in puppies.[18]
A 12-month study undertaken for the Winn Feline Foundation by researchers from the UC Davis School of Veterinary Medicine sought to compare the effects of a whole ground rabbit diet with a high quality commercial diet on 22 kittens and adolescent cats. The ground whole rabbit diet (including fur and organs) was frozen in small batches and thawed prior to feeding. The researchers noted the superior palatability of the raw rabbit diet. Significant stool quality improvements were seen in the raw rabbit diet group after one week. After one month, the raw diet group had firm, non-odorous and well formed stools while the commercial diet group had soft formed to liquid stools. The raw diet group also appear to have better coat quality. There were no differences between the groups in terms of growth rate, degree of inflammation in the intestinal tract and the numbers of bacteria in the upper small intestine, although a slightly higher number of cats in the raw diet group were shedding pathogenic organisms (Giardia and Cryptosporidia) in their stools. Ten months into the study, one cat in the raw diet group died suddenly from dilated cardiomyopathy due to a severe taurine deficiency. 70% of the group had heart muscle change compatible with taurine deficiency. The researcher ascertained that the raw rabbit diet contained the minimal requirement of taurine but speculated that bacteria in the rabbit carcasses might have broken down some of the taurine. The processing and grinding of the rabbit might have also caused some of the taurine to be destroyed due to the low level of vitamin E in the diet. The authors conclude that "a natural diet may not always be as healthy as imagined, and that even measuring nutrient values may not predict how a diet will perform after being fed for many months."[19]
While some proponents of raw diets recommend consultation with a veterinarian or animal nutritionist to verify that proper nutrients are being ingested,[20] others dismiss the importance of AAFCO standards, claiming that AAFCO certification is not indicative of the quality of a diet. An AAFCO panel expert has stated that "although the AAFCO profiles are better than nothing, they provide false securities."[21] Many cite that the oldest dog ever recorded, a 29-year-old Australian cattle dog named Bluey, died in 1939, several years before commercial pet food was invented, and that, of the two oldest dogs in recent years, one was fed primarily on kangaroo and emu meat.[22]
Some proponents of raw diet claim noticeable benefit to the dental hygiene of pets who eat raw bones, while others believe that ground bone should be used instead, to prevent the possibility for intestinal puncturing and dental fractures. The abrasion between bone and teeth when chewing is believed to scrape off dental plaque. Cartilage, ligaments, and tendons are thought to act as a natural dental floss.[23] The chewing and tearing action is also believed to strengthen the jaw, neck and shoulder muscles, keep the digestive juice flowing and boost the neurological and immune system.[24] Proponents of ground bones believe that the chewing of muscle meat may also assist in keeping teeth clean.
The use of whole bone creates a risk of dental fractures,[25] intestinal obstruction, gastroenteritis, and intestinal perforations.[17][26] Wolf care managers questioned on the topic of feeding bones identified the presence of animal hide with hair as offering some protection from intestinal perforation in the wild.[27] An analysis of the skulls of African wild dogs showed that the natural diet of wild carnivores does not prevent them from suffering the same oral disease as their domestic counterpart, although other studies have had results that claim otherwise.[28] Raw diet proponents note that the same risks of obstruction, puncturing, and dental fractures are present in dog chews, with little evidence indicating that this is a serious problem particular to raw diets with bones. Some veterinarians state that chewing raw bone is an inadequate substitute for regular dental cleaning and tooth brushing.
While the intense heat used in manufacturing pet food destroys any potential bacteria, raw meats may contain bacteria that are unsafe for both dogs and cats.[29] The US Government reported that in 2006, 16.3% of all chickens were contaminated with Salmonella.[30] A study on 25 commercial raw diets for dogs and cats detected salmonella in 20% and Escherichia coli in 64% of the diets. However, the E. coli strain that can cause severe illness O157:H7 was not tested for.[31] An example of the severity of E. coli H157:O7 infections can be seen in affected greyhound racing dogs fed raw meat as part of their diet. Known in greyhounds as "Alabama rot", the disease causes severe vasculitis, cutaneous necrosis, renal failure and death. It should be noted that racing greyhounds are typically fed raw meat classified as "not for human consumption", which may contain higher than normal levels of bacteria.[32]
Raw feeders consider the risk overblown and claim that the stomach enzymes and short intestinal tracts of dogs and cats allow them to handle harmful bacteria.[33][34] For example, an outbreak of salmonellosis caused by tainted commercial dry dog food led to 62 cases of human infection but no reports of the disease affecting animals fed the tainted food.[35] On the other hand, there has been a reported case where two cats fed a raw diet developed salmonellosis and died as a result.[5] A veterinarian from the National Animal Poison Control Center suggests that the diarrhea in animals that raw feeders attribute to detoxing could be caused by pathogens such as Salmonella, E. coli, Clostridium and Campylobacter.[5] The purchase of good quality meat from reputable sources and proper food safety practices such as defrosting meat in the refrigerator and not leaving food out for too long can reduce the proliferation of bacteria present in the meat.
Raw meats may also contain harmful parasites. As with bacteria, these parasites are destroyed during the heat processing of manufactured pet foods. Some raw diet recipes call for freezing of the final product, which greatly reduces (but does not necessarily eliminate) the potential for parasites. According to a former European Union directive,[36] freezing fish at -20°C (-4°F) for 24 hours kills parasites. The U.S. Food and Drug Administration (FDA) recommends freezing at -35°C (-31°F) for 15 hours, or at -20°C (-4°F) for 7 days.[37] The most common parasites in fish are roundworms from the family Anisakidae and fish tapeworm.[38] While freezing pork at -15°C (5°F) for 20 days will kill any Trichinella spiralis worm,[39] trichinosis is rare in countries with well established meat inspection programs,[40] with cases of trichinosis in humans in the United States mostly coming from consumption of raw or undercooked wild game. Trichinella species in wildlife are resistant to freezing. In dogs and cats symptoms of trichinellosis would include mild gastrointestinal upset (vomiting and diarrhea) and in rare cases, muscle pain and muscle stiffness.[41]
A survey of accredited zoos worldwide showed a slightly increased risk of parasites and diseases in animals that are carcass fed as compared to commercial food fed. However, the researchers suggested that that may be caused by increased opportunistic preying and infected live preys may be the source of contamination.[42]
A possible risk of raw feeding is that of human infection caused by direct or indirect exposure to bacterial pathogens in raw meat and animal stools. For example the British Veterinary Association warns that humans "risk exposing themselves to bacteria like Salmonella".[43] A small study on the levels of salmonella in the stool of 10 dogs that ate a raw diet found that 80% of the raw diet tested positive for Salmonella and while 30 percent of the stool samples from dogs fed a raw food diet contained salmonella, none of the control dogs (commercial fed) contained Salmonella. The authors of the study concluded that dogs on a raw food diet may therefore be a source of environmental contamination, although they caution about the statistical significance of their results due to the small number of dogs studied.[44]
Because of the potential animal and human health risks, veterinarian organizations and public health agencies believe that the risks inherent in raw feeding outweigh the purported benefits.[45] Despite such concerns, there is no known incidence of humans being infected with salmonella by cats and dogs fed a raw diet.[46] Again, proper food safety precautions such as wiping down preparation surfaces and careful disposal of stools can reduce the risk of infection.
After the 2007 pet food recall, interest in raw and cooked homemade pet food grew tremendously.[47] As a result of that, several pet food manufacturers now offer frozen raw diet products for pet owners. Some consumers believe that many of the same issues they find with commercial pet foods exist with packaged raw diets, others use it due to its convenience and for products with AAFCO certification, its assurance of a nutritionally balanced product.
The commercial raw pet food market is estimated to be worth $169 million a year (2007 figures), less than 1% of total pet food sales figure in North America($18 billion). Growth is estimated at 23% per annum.[48]
Many commercial raw pet food manufacturers now use High Pressure Pasteurization (HPP), a unique process that kills pathogenic bacteria through high-pressure, water-based technology. High Pressure Pasteurization is a USDA-approved, 100% natural process, and is allowed for use on organic and natural products.
Veterinary associations such as the American Veterinary Medical Association, British Veterinary Association and Canadian Veterinary Medical Association have warned of the animal and public health risk that could arise from feeding raw meat to pets and have stated that there is no scientific evidence to support the claimed benefits of raw feeding.[43][45]
More recently in 2007, The Sydney Morning Herald (paraphrasing RSPCA Australia President Dr Hugh Wirth) reported that "the 'compromise attitude' of veterinary associations in Britain and Australia is that raw meaty bones should be fed to pets a minimum of three times a week for dental health."[49]
It is believed by many raw feeders that veterinarians are influenced by academic departments and professional associations that rely upon funding from pet food companies.[50] For example, Hill's Pet Nutrition, makers of Science Diet and a range of prescription-only food, is a major sponsor of the American Veterinary Medical Association.[51] Another common belief is that veterinarians lack adequate education on raw diets or nutrition in general.[43] Frequently, veterinary schools receive nutrition training that is sponsored or directly provided to students by pet food manufacturers.[52] The Wall Street Journal reports that Hill's "spends hundreds of thousands of dollars a year funding university research and nutrition courses at every one of the 27 U.S. veterinary colleges" and that vets profit as much as 40% from sales of Science Diet and other foods sold from their offices.[53] Raw feeders are often skeptical of the motives that some veterinarians have in recommending the commercial foods they sell, pointing out the conflict of interest in them doing so.
One study used by many people feeding pets a raw diet to back up their claims of raw food being superior to cooked food is Francis M. Pottenger, Jr.'s study of 900 cats over a period of 10 years from 1932 to 1942.[54] His results showed that cats that were fed 2/3 raw meat, 1/3 raw milk and a small amount of cod liver oil were disease free and healthy while those fed the same food with the meat cooked developed degenerative diseases and reproductive difficulties, with new generations plagued with health problems. The study was done before the importance of taurine in a cat's diet was known and it has been suggested that the group of Pottenger's cats on cooked food simply suffered from taurine deficiency as heating or cooking food causes a reduction in taurine content.[55] Pottenger himself concluded that there was likely an "as yet unknown" protein factor that may have been heat sensitive. In a study on feline maternal taurine deficiency, the group of taurine-deficient cats exhibited symptoms similar to the Pottenger's cats on a cooked diet.[56]
In another study, the cats were fed 2/3 milk and 1/3 meat. All groups were fed raw meat with different groups getting raw, pasteurized, evaporated, sweetened-condensed, or raw, metabolized vitamin D milk. The cats on raw milk were the healthiest while the rest exhibited varying degrees of health problems similar to the previous cooked-meat study.[57] This study has been cited by raw milk proponents as evidence of the benefits of raw milk.