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Raw feeding
Raw feeding is the practice of feeding domestic dogs, cats and other animals a diet consisting primarily of uncooked meat, edible bones, and organs. The ingredients used to formulate raw diets can vary. Some pet owners choose to make home-made raw diets to feed their animals but commercial raw food diets are also available.

The practice of feeding raw diets has raised some concerns due to the risk of food borne illnesses, zoonosis and nutritional imbalances. People who feed their dogs raw food do so for a multitude of reasons, including but not limited to: culture, beliefs surrounding health, nutrition and what is perceived to be more natural for their pets. Feeding raw food can be perceived as allowing the pet to stay in touch with their wild, carnivorous ancestry. The raw food movement has occurred in parallel to the change in human food trends for more natural and organic products.

Rationale
Feeding raw pet food is a new trend among pet owners and can be correlated with the increased consumption of organic food in humans. Some owners that humanize their pets, may feel more connection to their pets as they are more involved in the feeding process by preparing the food. Many dog owners choose to feed a raw diet as they feel it better fulfills their dog’s natural predator instinct. Feeding a diet that resembles what the wolf, the domesticated dog’s closest ancestor, would eat is a more "natural" feeding method. ] Supporters of the raw food diet movement cite many beneficial health claims in feeding raw food over processed commercial pet food.

Bone and Dental Health
Diet plays a significant role in promoting both good bone and good dental health through the maintenance of the calcium to phosphorus ratio. Up to 99% of a dog’s calcium and 85% of phosphorus are found in bone and teeth. An ideal ratio of calcium:phosphorus in dogs is 1.4:1. Maintaining an optimum ratio allows for the continued tight regulation of calcium metabolism, which is important to many normal physiological functions throughout the body.

Phosphorus is easily available in many food sources, however, phosphorus bound to phytates has much lower bioavailability. Finding foods that provide sufficient amounts of calcium to maintain a good ratio is challenging, as many food that are high in calcium are also high in phosphorus. For this reason, creating a homemade raw diet with an appropriate calcium:phosphorus might prove difficult, especially without the analysis techniques that are available to the commercial food producers.

Including bone in raw diets is commonly practiced, as it is a good source of both calcium and phosphorus. Feeding raw bone can have some adverse effects on a dog’s health if fed in whole form. Whole bones in the diet increase the risk of dental fractures, intestinal obstructions, gastroenteritis, and intestinal perforations. Feeding ground bones instead of whole bones reduces the risk of these adverse effects.

Skin and Coat Health
Many raw diets focus on promoting a healthy skin and coat, mainly through the supplementation of essential fatty acids. Fatty acids play an important role in the structure and function of cells, while also improving palatability of the diet. Omega-6 (n-6) and omega-3 (n-3) are especially important for normal skin function and appearance. The skin’s ability to produce long chain fatty acids, such as linoleic acid (18:2n-6) and linolenic acid (18:2n-3) is limited. For this reason, these fatty acids are especially essential for skin health and many raw diets make sure they are properly supplemented.

To improve skin and health coat, essential fatty acids are supplied in excess of the Association of American Feed Control Officials (AAFCO) requirements, which results in improved coat sheen and skin health. Omega-6 fatty acids, linoleic acid in particular, play an important role in skin barrier function. Omega-3 fatty acids also plays an important role in skin health as they help reduce inflammation and can even protect against UV damage.

Fatty acids supplemented into raw food diets often are seen in a variety of forms. Common sources of omega-6 fatty acids in raw diets often include flaxseed, pumpkin and sunflower seeds. All these ingredients can be fed as whole seeds or as oils. The best sources of omega-3 fatty acids are fish oils, which are usually found in most raw diet formulations.

Protein Availability
When commercial pet food is made, ingredients in the food are exposed to high temperatures, creating a risk of maillard reaction. Maillard reactions are problematic as when this reaction occurs, a reducing sugar binds to the amino group on the amino acids, making the amino acids unavailable to the animal. The amino acid most affected by this reaction is lysine, which is an essential amino acid and the first limiting amino acid for the dog and most other vertebrates. Lysine plays a major role in the body including in protein synthesis, as well as carnitine synthesis and obligatory oxidation. Thus, some forms of food processing may reduce the amount of available essential nutrient in a dog's food.

Due to the fact that raw diets do not exposure the meat to any high temperatures, the chance of the maillard reaction happening is greatly decrease. This means that the amino groups of the amino acids in the meat will be unbound and nutritionally available to the dog for use. However, the risk assumed by not cooking or processing meat is an increased chance of bacterial infections to the pet or the owner handling the food.

Raw diet type
There are various differences in opinion within the raw feeding community. Issues include whether dogs are omnivores or carnivores, whether dogs need plant material in their diet and if so, in what quantities. The safety of whole bones use is also a frequent topic of discussion. Raw diet recipes can range from meat with a wide selection vegetables and grains, while other are more minimalist, using only meat, bones, organ meat, and necessary supplements. An example of an minimalist approach to raw feeding is the Meat with Bone diet advocated by Michelle T. Bernard. Critiques of raw diets include the concern with the possible nutrient imbalances that can arise feeding any type of raw diet.

Raw-Meat Based Diet
Raw-meat based diets (RMBDs) are composed of uncooked ingredients derived from animal species that are fed to dogs in home environments. Ingredients can include a variety of animal parts including muscles, organs and bones. RMBDs can be designed commercially or home-prepared by the owner. Commercial RMBDs are typically formulated to meet AAFCO nutrient requirements although some products are designed for supplementation and are not nutritionally balanced.

BARF
The BARF diet was originally defined as Bones And Raw Food diets but has since been changed to Biologically Approved Raw Food. The original BARF diet was popularized by Dr. Ian Billinghurst, advocating feeding 60% raw, meaty bones. The rest of the diet is to be composed of a wide variety of foods including vegetables, grains and legumes.

Prey model diet
The "prey model" diet attempts to create a diet that simulates the proportions of ingredients and nutrients seen in a prey animal's diet. In the wild, a predator gains nutrients not only from the meat and organs of the prey they are eating. A wild animal would also gain nutrients from the food their prey has previously consumed. This diet aims to simulate all the nutrients that the wild animal would obtain.

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 natural carnivores and do not have any nutritional needs besides what is found in meat, bones, and organs. The supporters of the prey model also focus on feeding meats from a wide variety of animals. Some also add small amounts of vegetable matter to simulate the consumption of stomach contents of prey animals.

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. This problem can be partially mitigated by using grass-fed meat, which has more than double the omega-3 content as grain-fed meat.

In addition, very little scientific data exists to back-up that the prey model diet, especially in terms of ingredient composition and ratios, is actually beneficial for the dog's health.

At home
At home preparation of raw food diets entails the use of wholesome ingredients that can be easily accessed by the owner. The main critique of homemade raw diet is that they are often formulated based on opinion rather than scientific research. Preparing of raw diets can be time consuming and requires the handling of raw meat.

Examples of homemade diet theories include: BARF, the Ultimate Diet and the Volhard Diet. Included ingredients are supposed to mimic the diet an animal would eat in the wild such as meat, bones, vegetables, and organ meats. Supplementation of vitamins, minerals, essential fatty acids, and probiotics are often included to provide the animal with a complete diet or to offer a variety of benefits to the animal.

In most dog homemade diets, a variety of ingredients are included which may include: Pet owners are advised to keep in mind that homemade diets can be hard to balance properly and can be associated with poor nutrition. Proper research and understanding of what nutrients the homemade diet offers is crucial. It is also important to recognize the nutritional needs of the animal, which can change given factors such as life stages, breed and overall health.
 * Fresh raw meat (mostly lean meat with the exception of pork for some dogs, beef is the most commonly used)
 * Vegetables such as: squash, pumpkin, leafy greens, carrots, parsley, etc...
 * Offal such as liver
 * Fruits such as: apples, cranberries, blueberries, etc...
 * Stocks, soups, milk or water for added moisture
 * Some cereal foods such as: barley, flax, etc...
 * Some supplements
 * For dogs: uncooked bones in the diet or allowing the animal to play with raw bones as a treat

Commercial
After the 2007 Pet Food Recall, interest in homemade pet food (both cooked and raw) grew tremendously. As a result, several pet food manufacturers now offer frozen raw diet products for pet owners. The commercial raw pet food market is estimated to be worth $169 million a year, less than 1% of total pet food sales figure in North America ($18 billion). Growth is estimated at 23% per annum.

Many consumers prefer raw commercial diets over raw homemade diets due to its convenience. Most commercial diets are formulated to meet the requirements of AAFCO Dog or Cat Food Nutrient Profiles. The diets are formulated to satisfy values needed for the different life stages whether that be adult maintenance, growth, gestation or lactation. Some raw products are meant to be used as supplemental feeding only as they are not nutritionally complete or balanced. Raw commercial diets are usually pre-packaged and can be fresh, frozen or freeze-dried. Commercial raw diets are easy to handle, include feeding instructions and enable the owner to avoid touching raw meat Most, but not all, commercial raw diets include all the essential nutrients that the animal requires.

Many commercially sold raw food diets are treated by high pressure pasteurization (HPP). HPP sterilizes the food from pathogenic bacteria and extends the shelf life of the product. During HPP, the food is placed in a water-filled chamber and intense pressure is applied. High pressure pasteurization is a USDA-approved food processing technique. Although this method helps kill most bacteria, HPP cannot destroy all pathogens.

The FDA has released a document that gives guidance for the raw pet food industry on preparation, labelling, storage and transport.

Supplements
When feeding raw diets, considering adding supplements to the animal’s diet may be very beneficial. Supplements aid in providing the animal with a high quality, complete and optimal diet. Supplements may also be useful in improving an animal’s health, especially when that animal has specific health issues. Some raw dog diets have been found to be low in the following nutrients such as vitamin E, zinc and iodine, hence why supplementation can be advantageous. There are a variety of supplements that can be given to and animal and getting the opinion of a veterinarian or an animal nutritionist may be helpful.

Example of vitamin supplements: Example of fatty acid supplements: Example of mineral supplements: Example of probiotics supplements:
 * Vitamin E is an antioxidant that is not present in raw meat. It is acquired from plants. Providing Vitamin E supplementation may benefit the dog as it is theorized to reduce inflammation and help aging dogs with brain cognition.
 * Fish oil supplements aid reach the ratio needed for omega-3 and omega-6 fatty acids.   Omega-3 fatty acids are anti-inflammatory and therefore help improve coat help, reduce intestinal inflammation and more.
 * Zinc is essential for maintenance and supplements may be needed in some raw diets
 * Kelp supplements are given to increase the iodine that the animal gets.   Iodine is essential in the production of thyroid hormones.
 * FortiFlora is a commercially available supplement that aids in decreasing gastrointestinal problems in addition to supporting immune health.

Nutritional balance
Further information: Pet food § Labeling and regulation

The nutritional balance of a raw diet can vary greatly depending on the diet formulation. Some raw diet proponents prefer to use a variety of ingredients to provide a more balanced diet than a single food source. It is possible to meet all nutrient requirements feeding a raw food diet, but it is essential to know what ingredients are included in the diet and how they all contribute to meet the dog's nutrient requirements.

The following table provides a list of potential ingredients that may help contribute to a balanced diet and ensure that a dog's nutrient requirements are met:

Deficiency Problems
According to a study on homemade raw diets, very few owners follow a recipe, therefore, resulting in a risk of nutritional imbalance.

In terms of vitamins, the presence of avidin in raw eggs can bind to biotin and make it unavailable for absorption which can lead to a deficiency. Raw fish has high level of thiaminase activity that can breakdown thiamine and lead to a deficiency. Liver, often used in raw diets, is rich in vitamin A. High amounts of liver can cause vitamin A toxicity, called hypervitaminosis A.

The Association of American Feed Control Officials (AAFCO) provides standards that guides many commercial pet food companies, a level of supervision that does not occur with homemade food. One study 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, showing nutritional imbalances in the homemade diets. Three of the diets had inadequate calcium-to-phosphorus ratios, which may lead to hyperparathyroidism and fibrous osteodystrophy in puppies. As well, homemade diets were proven to have deficiencies in vitamin D, important for bone health by facilitating calcium absorption in the gut, which contribute to storage in bone, and vitamin E, which improves overall immune function by reducing oxidative stress. Oxidative stress happens when free radical formation, which is a natural process, excess the body’s ability to destroy them, resulting in cellular damage and inflammation. Antioxidants improve the destruction process by scavenging the free radicals. Many macro-minerals were also undersupplied such as, Zinc, Potassium and Sodium in the homemade puppy diet.

Another issue with raw diets is the non-inclusion of carbohydrate sources, due to the common misconception that dogs cannot digest starch. According to a paper published in Nature, dogs have acquired the ability to digest starch and it can be used as a readily available energy source. Furthermore, the inclusion of dietary fiber sources is important for a dog's gastrointestinal health and stool quality. The moderately fermentable fibers will form a gel in water and have a lower transit time in the intestines, which will give the microbiota more time to ferment the fiber into short chain fatty acids, used by the enterocyte as energy. The net result of this will be a healthier villi which will maximize absorption.

Some proponents of raw diets recommend consultation with a veterinarian or animal nutritionist to verify that the raw diet includes proper nutrients that can be properly digested. Others dismiss the importance of AAFCO standards, claiming that AAFCO certification is not indicative of the quality of a diet.

Food Safety
While the intense heat used in manufacturing pet food or cooking meat destroys bacteria, raw meats may contain bacteria that can be unsafe for both dogs and cats. The United States government reported that in 2006, 16.3% of all chickens were contaminated with Salmonella. 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. 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. A contributing factor might be that racing greyhounds are typically fed raw meat classified as "not for human consumption", which may contain higher than normal levels of bacteria.

Another study performed to assess the risk of dog feed analyzed 240 samples from either raw meat dog diets, commercial dry dog food or commercial canned food. Salmonella enterica was found in almost 6% of the raw diets, while Escherichia coli was found in almost 50% of the raw diets. E.coli was also found in the commercial dry and wet dog foods, but in lesser amounts. This study determined that bacterial contamination is more common in raw meat diets than commercial dry or canned foods.

Supporters of raw feeding, Dr. Richard S Patton, report that the stomach enzymes and short intestinal tracts of dogs and cats allow them to handle harmful bacteria. Most dogs that carry salmonella are asymptomatic. In one reported case, two cats fed a raw diet developed salmonellosis and died as a result. 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. Bacteria proliferation in any meat can be reduced by following proper food safety practices such as defrosting meat in the refrigerator or by cooking raw meat, both of which reduce the risk of pathogens.

Raw meats may also contain harmful parasites. As with bacteria, these parasites are destroyed during the heat processing of cooking meat or manufacturing pet foods. Some raw diet recipes call for freezing meat before serving it, which greatly reduces (but does not necessarily eliminate) extant parasites. According to a former European Union directive, 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. The most common parasites in fish are roundworms from the family Anisakidae and fish tapeworm. While freezing pork at -15 °C (5 °F) for 20 days will kill any Trichinella spiralis worm, trichinosis is rare in countries with well established meat inspection programs, 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.

Zoonotic Risk
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. A small study investigated the levels of salmonella in the stool of 10 dogs that ate a raw diet. It was found that 80% of the raw diets tested positive for Salmonella and 30% of the stool samples from dogs fed raw food contained salmonella. None of the control dogs fed a commercial feed contained Salmonella. The authors of the study concluded that dogs on a raw food diet may be a source of environmental contamination, although they caution about the generalizability of their results due to the small number of dogs studied.

While raw dog food can contain Salmonella, commercial dog food is not also free from the bacteria. Centers for Disease Control and Prevention released a general warning about contamination of commercial dry dog food and treats by Salmonella.

As a result of the potential animal and human health risks, some agencies assert that the risks inherent in raw feeding outweigh the purported benefits. Despite such concerns, there is no known incidence of humans being infected with salmonella by cats and dogs fed a raw diet. There has been isolated cases of humans contracting salmonella from from household pets, but it is undetermined whether raw food was connected to the salmonella infection. The FDA recommends cleaning and disinfecting all surfaces that come in contact with raw meat, as well as thoroughly washing hands your hands, to reduce the risk of coming in contact with harmful bacteria.

Veterinary Position
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. Dr Tom Lonsdale in Australia has been a long-time and prominent veterinary advocate of raw feeding.

Veterinary associations often organize debates and panel to further the understanding of health and nutrition when feeding dogs. In 2016, the British Small Animal Veterinary Association Congress, discussed the health implications and nutritional balance of raw feeding. The main ideas resorting from this panel were that raw feeding could potentially lead to health and nutritional imbalances when owners did not comply with guidelines such that education of owners was critical.

There are now considerable numbers of veterinary surgeons who advocate species-appropriate diets including raw feeding dogs and cats. The Raw Feeding Veterinary Society (RFVS) was founded in the UK in 2014 and organizes conferences and discussions regarding raw feeding and related issues for Veterinary Surgeons and Nurses.