The Evidence Based Nutrition

Published Date: 02 Nov 2017

Assignment One ~ Literature Review

Kimberley Williams

Evidence Based Nutrition: Raw meat and Bone Diets for Dogs

ABSTRACT

In recent years there has been an increase in the ownership of the domesticated dog and a change in the feeding habits of our canine friends. Around 60 years ago dogs were eating scraps, carcasses and whatever else they could catch, but as increased awareness of dietary requirements was forced into the open, the commercial pet food industry came to power encouraging all pet owners to feed what we thought was a balanced and nutritious diet for our dogs. With this increase in commercial pet food also came an increase in health problems, sensitivities to food, allergies, mal nutrition leading to growth deformities and also an increase in metabolic and other diseases (Boermans & Leung 2007; Freeman & Michel 2001).

On the other side if the nutrition debate is the raw meat and bone diet, which is becoming an increasingly popular choice when compared to the known, let downs of the commercial brands of pet food. This diet promotes increases in coat and skin condition, beneficial effects on the immune function and overall health, an increase in energy, and also positive effects on diseases like chronic digestive issues, allergic reactions and metabolic diseases. (Weese, Rousseau & Arroyo 2005; Freeman & Michel 2001). This diet promotes a natural and traditional diet in that it bases the ingredients on those that were a major part of the dog’s diet all those years ago. The major components of this diet are raw meats such as chicken, beef, turkey, pork, quail, venison, lamb or any other type of animal meat that is in supply and a mixture of vegetables, greens and roughage (usually being bones). Dogs have been eating raw meat for centuries even after they had been domesticated they were fed on raw meat, off cuts and human scraps and still did not have the number of health issues that exist in the canine community now. This very fact supports the belief that this diet is not only better than commercial pet food it is more nutritiously beneficial and a complete food source (Schlesinger & Joffe 2011).

There is only a small amount of literature that supports or negates an organic raw food diet there is a variety of conditions that are mentioned throughout the studies that have been attributed to poor nutrition either from a raw food diet or from the lack of proper nutrients available in commercial dog foods (Joffe & Schlesinger 2002). This review will look at the literature available on the topic of raw food and bone diets, highlighting the benefits and risks associated with a raw food and commercial food diets, the risk of bacterial contamination for both the dog and their owners as well as the implications of long term feeding a raw meat and bone diet.

INTRODUCTION

A raw meat and bone diet is becoming a popular trend due to the belief that this diet provides a more nutritiously complete food source. Currently there is little substantial evidence of this and only small studies have been conducted in the past few years due to either lack of funding or availability of test subjects. The small studies that have been conducted have produced both positive and negative results, unfortunately none of which had enough statistically important data produced to support either of the claims (Joffe &Schlesinger 2002; Weese, Rousseau & Arroyo 2005; Freeman & Michel 2001; Strohmeyer et al. 2006). Contamination risks in both the raw meat and bone diets as well as commercial pet food diets is also a highly discussed topic amongst the papers, contamination with Salmonellae and other pathogens from inadequately prepared have caused complications with human health risks and other canines through the shedding of these pathogens in fecal matter. The recent studies and advertisement has increased the awareness of owners to the risks of commercial pet food and its industry, the studies that have been reviewed all support the claim that heat processing that takes place to produce canned pet food alters or destroys the essential nutrients and enzymes, therefore making the argument that these meals may not be natural or nutritionally sound (Freeman & Michel 2001). While others say that when weighing up both the pros and cons of the raw meat and bone diet compared to the commercial, there will be a decreased risk of bacterial contamination due to the heat treating and therefore have a decreased risk of shedding and human health risks are minimised (Weese, Rousseau & Arroyo 2005; Strohmeyer et al. 2006; Hill 1998; Joffe &Schlesinger 2002; Schlesinger & Joffe 2011). There have been a variety of benefits published to encourage the use of raw meat and bone diets for both show and race dogs, none of which have provided substantial evidence within their individual studies. Although some say that meat remains an unbalanced food and is deficient in many essential nutrients and vitamins. If the majority of the canine’s regular diet is meat without adequate supplementation of vitamins it can lead to hyperthyroidism, poor bone mineralisation and increased risk of bone fracture in dogs (Hill 1998).

NUTRITIONAL BENEFITS

There are many studies that claim the positive benefits of a raw meat and bone diet. This diet is based on the traditional diets of the canine species long before they were domesticated. Raw meat, bones, vegetables, Greens, fruit and other types of herbs were a major part of the dog’s daily diet. In recent years with the domestication of the dog came the need for a nutritionally balanced and healthy diet. This diet has said to promote healthy coat and skin condition, aids in the elimination of bad breath and body odour, improvements in available energy which is very important in racing or high endurance dog breeds, also noted is an improvement in mood, overall health and reduced susceptibility to health conditions and disease. These improvements have yet to be substantiated with a large enough study (Freeman & Michel 2001).

There are many studies that frown upon this diet due to the risks of contamination, but there are also a few that have concluded a positive result even with their small survey group. A survey conducted on the feeding practises in the United States and Australia conducted a survey and found that 98.7% of dog owners and 98.5% of cat owners that fed their animals on an all raw meat and bone diet over a period of three months deemed their pets healthier after the trial period. The pets were all fed bones or raw food as part of the main meal and that less than 3% of the owners fed their pets exclusively home prepared diets. (Schlesinger & Joffe 2011; Laflamme et al. 2008). The conclusions of this study were not statistically reliable and the results were not measurable as the test was deemed a success by the individual owners which are open to bias, and the results were not able to be reproduced due to the small testing group and the lack a financial support.

A second study that also assessed the effects of animal by-products and processing temperature on amino acid digestibility, found that from the six home made products tested (that contained animal by-products, specific amino acids and products) there was an increase in the total digestibility of the amino acids and nutrients in the dogs fed a raw meat and bone diet whereas a canned food diet with meat which has been heat treated showed a decreased digestibility of the essential nutrients available (Murray et al. 1988; Johnson et al. 1988).

This same conclusion was also noted in a review by Schlesinger and Joffe 2011, they found evidence that digestive enzymes in fresh or raw food enhance biological availability when being digested and that heating depletes these enzymes and therefore the nutritional quality of the food. Murray et al. also supported this theory and found that the nutrient intakes were higher for all nutrients when the dogs were fed on an all raw meat diet these results were compared to commercial canned diets.

The benefits from this diet come from the fact that the raw food and its higher levels of fats are much more digestible by the ilium of dogs, and seeing as dogs have a high oxidation rate of fats means that the require higher amounts of natural fats in order to maintain condition.

Therefore reinforcing the belief that this diet is much more natural and healthier for the overall condition and maintenance (Hill RC 1998).

Although this diet has many proposed nutritional benefits it has been identified by several papers that the decision to feed dogs this type of diet must be well researched by the owner and that they should be formulated by a qualified nutritionist to ensure that minimal detriment is caused to the dog or cat (Freeman & Michel 2001; Murray et al. 1988; Johnson et al. 1998).

NUTRITIONAL RISKS

There are a number of sources and reviews that inform of the implications of feeding a raw meat and bone diet, most of these studies however have only studied the short term effects of feeding this diet and none as of yet have reviewed the longer term effects that could occur.

The Nutritional imbalances of vitamins and some essential nutrients are a highly discussed downfall in this diet. A small study that tested three dogs being fed a raw food diet for a 6 month period, found that the food contained low levels of calcium, phosphorus, potassium, manganese and zinc. They also noted that the diets contained unbalanced calcium to phosphorus ratios and higher than normal levels of Vitamin D (Freeman & Michel 2001). All of these deficiencies could lead to a variety of conditions including growth deformities, and even death.

A study in 2009 by Taylor et al. identified diffuse osteopenia and myelopathy in a puppy that was fed a raw meat diet. The findings were that the dog’s diet had caused an imbalance in both macronutrients and macrominerals. This is believed to have caused a series of problems including polyostotic deformities, osteopenia, cranial cervical myelopathy and a degree of hypocalcaemia and hypophosphatemia was also detected. The conclusion was that these problems were if not caused by were accelerated by the fact that the dogs was being fed a nutritionally unbalanced diet of raw meat and was not able to obtain the essential nutrients and vitamins necessary to grow healthily.

A study Johnson et al. identified that the nutrient levels and amino acids present in each sample they tested were highly variable and inconsistent which could create problems in maintaining a healthy diet and for substituting vitamins into the diet, as the levels would be forever changing in order to create a balanced and complete meal. It was also noted that although this variability exists it does not change the high digestibility of a raw food diet; however temperature plays an important role in the health of this diet.

CONTAMINATION RISKS

Bacterial and protozoal contamination is a commonly noted in the literature available on this diet. One study found that 80% of the homemade raw diets they tested contained a concern-able amount Salmonella spp. And that 30% of those cases also showed up in the fecal matter. The study also noted evidence of other types of bacteria present in raw food, like Campylobacter spp., Escherichia coli, Staphylococcus aureus, Clostridium perfringens and some other clostridia (Lejeune & Hancock 2001; Weese, Rousseau & Arroyo 2005; Brown et al. 2007).

Another study tested twenty five raw diets from eight different manufacturers. Thirteen of these were for dogs and eight were for cats the others were not intended for either. The study found that the most common of the meats found in these diets was chicken at 28% and the others were a mixture of beef, ostrich, rabbit, salmon, turkey, quail, goose, buffalo and venison. When the study tested each of the diets they found that coliforms were present in all of the twenty five diets, four of which had excess coliforms present. When tested for specific bacteria the study identified Escherichia coli in 16 of the diets, Monophasic S. Typhimurium was detected in 5 of the diets. Salmonella spp. was found in all of the diets containing chicken, beef, lamb and quail. This study was also assessing the issue of human exposure risks to these bacteria. The handling of food bowls and feces from animals being fed a raw food diet increase the risk of these bacteria being passed to the human. The shedding of bacteria in fecal matter also poses a problem, as this enables the bacteria to not only spread to the humans sharing the environment but also the other animals. Immune-compromised people and animals (The young, elderly or sick) are at high risk of picking up these pathogens and organisms from the ground or from surfaces that are contaminated. Therefore hygiene is of the up most importance when feeding this diet, removing of excess food from the ground, cleaning food bowls with bleach, and regular fecal disposal is key to maintaining a healthy environment for both animals and humans (Wesse, Rousseau and Arroyo 2005).

Finley et al. conducted a study on twenty eight dogs to determine the prevalence of Salmonella shedding. The shedding rate of 44% in this study was higher than the 30% observed by Joffe and Schlesinger in dogs fed homemade raw food diets. This difference may have been because of the large difference in time periods in which the studies were conducted (Finley et al. 2007). Another study who tested the same prevalence of this pathogen found that, Salmonella was obtained from 47.6% of the raw meat diets tested (Strohmeyer et al. 2006).

A review by Hill 1998, noted that food borne infection was a prominent risk in feeding dogs raw meat. The increased risk of infection when feeding meat that is uncooked and unpasteurised increases when the temperature rises, if this meat is then fed to the animal the risk of E. coli releasing a toxin which is responsible for severe vasculitis, cutaneous necrosis, renal failure is almost certain and can lead to death in some cases. Cooking the meat prior to feeding would eliminate this risk of pathogens and other organisms from surviving in any harmful number. There is evidence that this method of reducing bacteria in the raw meat would not be popular due to the evidence that suggests when the meat is cooked it would destroy the potentially beneficial nutrients and vitamins (Lefebvre et al. 2007; LeJeune & Hancock 2001). There are other methods available to reduce the risk of bacterial contamination of meat; things like defrosting the meat in the fridge, serving and preparing the meat at a low temperature will also help (Weese, Rousseau & Arroyo 2005; Strohmeyer et al. 2006; Hill 1998; Brown et al. 2007; Joffe &Schlesinger 2002).

However the risks are equally associated with commercial pet food, aside from the heat treating which destroys the enzymes and other nutrients, contamination risks also exist in canned commercial pet food. Studies have found that melamine and Cyanuric Acid have been found in many pet food brands and have led to renal failure, urinary tract problems and crystallisation of urinary tubes (Boermans & Leung 2007; Brown et al 2007). This risk would be highly unlikely in a raw meat and bone diets as there is no need for this chemical to be used in the packaging or else were, due to the natural nature of this diet and its unprocessed state.

CONCLUSION

The Canine species has been consuming raw meat and bones for centuries, regardless of the contamination that occurs, even today dogs dig up bones with an immeasurable amount of bacteria and organisms on them and they have been doing this without adverse effect. It is only now with evidence of the harm that bacteria can cause that there is concern for how many of these organisms they ingest. Many studies have pointed out that bacteria, enzymes and vitamins play an important role in the digestion of foods and maintenance of health within the system, and that many of these good bacteria, nutrients and enzymes are more prevalent in raw food that has been untreated (Murray et al.1988; Freeman & Michel 2001). There is little substantial evidence within these studies to prove that this diet is the best option, but they do provide adequate information to the benefits of such a diet and why it could be considered to be beneficial to feed dogs an all Bone and Raw meat diet. There also still remains little to no research into the benefits of a gene specific diet which would nullify the need for a raw food diet or a commercial diet. This type of diet would provide a species specific diet composition to meet all the individual needs and inadequacies of the dog, and is considered by most as the most promising option for complete diet plan that will meet all the needs of the dog without supplementation.

It is important to note that although there is risk of contamination that the raw food option contains a huge advantage in its ability to provide highly digestible amino acids, nutrients and fats. This enables dogs to have increased energy and condition improvement as well as the benefits of added amino acids that they would not normally absorb with other diets (Schlesinger & Joffe 2011; Weese, Rousseau & Arroyo 2005). The studies have only been small and have produced a balance of positive and negative conclusions, drawn from very different perspectives, there needs to be further investigation into the long term effects of this diet and the inadequacies that may arise when this diet is fed as a major proportion of the total diet. These studies however informative have still not been able to provide statistically significant data to either supports or deny the benefits of this diet and there still remains a lot of research to be done (Finley et al. 2008; Finley et al. 2007; Finley, Reid-Smith & Weese 2006; Lefebvre et al. 2007; Schlesinger & Joffe 2011).