Paws In Progress: April 2014

We asked our Vet for more information on RAW feeding as we have found that many of our clients are now feeding it. These are the articles she forwarded on to us. We did not write them and do not claim them as our own. Each has the source attached or stated.

Raw Pet Food Diets: Parasites, Pathogens, & Perceptions

ACVIM 2008

Laura Duclos, PhD
Lincoln, NE, USA

18286523

Introduction

The issue of feeding dogs and cats raw meat diets has spurred much controversy and debate among the veterinary community, government regulatory agencies, and consumers. The recent melamine contamination has brought increased attention to raw diets and more pet parents are choosing to prepare raw food for their pets or to purchase commercially prepared raw diets. So, with the rise in raw food popularity and the availability of pet food cookbooks or commercial diets, the topic of raw food and potential zoonosis is gaining considerable attention.

Critics claim raw food diets are dangerous to pet and human health because of the risk of spreading helminths, protozoans, bacteria, viruses, and prions. They argue that raw diets represent a human and public health threat despite proper food handling and sanitation practices. Further, they state that pathogens in raw meat are capable of causing illness in dogs/cats and that bone leads to dental and gastrointestinal trauma. More importantly, critics are concerned about nutritional adequacy with regard to long-term feeding. Critics want scientific data supporting the health claims touted by raw food defenders.

Supporters of raw diets defend the health benefits of raw food, arguing raw diets are far superior to that of cooked food. While scientific data is lacking, they cite thousands of anecdotal reports and counter the critics with an explanation of dog/cat physiology, biology, behavior, and evolutionary ancestry. Proponents of raw food argue that many of the health issues facing pets today stem from the introduction of cooked pet food in the second half of the 20th century. They view raw diets as biologically correct nutrition, low risk, and are passionate about their beliefs.

Types of Raw Food Diets

1. Raw diets used at zoos, wildlife parks, wolf rescues, and greyhound facilities are usually fresh or frozen bulk raw meat purchased from slaughterhouses; meat quality is highly variable and may include 4-D (dead, dying, diseased, downed) animals, road kill, or other animals not fit for human consumption. Moreover, meat may be rotten and not handled/stored in a sanitary manner. Formulations may not include added vitamins and minerals and typically have not been through American Association of Feed Control Officials (AAFCO) feeding trials.

2. Bones and Raw Food (BARF) diets are consumer-bought meat and bones prepared at home; pet parents may or may not follow a recipe and meat quality/freshness is unknown. Bones are usually whole and purchased from butchers, which carries the risk of sharp edges and fragments. Raw meat and bones may not be handled/stored in a sanitary manner. Pet parents may or may not add vitamins and minerals and the formulation has most likely not been through AAFCO feeding trials.

3. Blends of dry fruit/vegetables/grains with added vitamins and minerals are designed to be purchased by the pet parent and combined with fresh meat from the grocery store to make a complete and balanced raw diet. Meat is typically human-grade and bones are usually not used unless as a treat. The raw meat may not be handled/stored in a sanitary manner. Formulations may or may not have been through AAFCO feeding trials.

4. Commercially-prepared raw diets are a mixture of raw meat, organs, vegetables, fruit, grains, and/or ground bones that may or may not include added vitamins and minerals. Diets are typically produced in accordance with Good Manufacturing Practices (GMP), are pre-packaged, and are sold frozen at specialty pet stores. The raw meat and bones are typically from inspected animals deemed fit for human consumption. If bones are included in the diet, they are usually ground; some companies sell whole bones that have been cut to minimize sharp edges or fragments. Some brands of raw diets, but not all, have been through AAFCO feeding trials.

Nutritional Adequacy of Homemade vs Commercial

Commercially prepared raw frozen diets typically do not contain raw soybeans or grains, sources of potentially anti-nutritive factors. As a commercially sold pet food, they must follow AAFCO guidelines, including a guaranteed analysis, feeding directions, and lifestage information. The issue of "complete and balanced" is less clear-cut since most manufacturers do not add vitamins and minerals; diets may not meet AAFCO nutrient guidelines for "complete and balanced" and must undergo feeding trials to carry such a claim. Conversely, homemade raw diets are typically formulated from recipes pet parents devise or glean from books and the internet. The source of the meat is often unknown and may be improperly handled/stored. Homemade diets have ambiguous nutritional profiles and are not consistent from batch to batch. Some owners may use added vitamins and minerals, but this poses a greater risk of nutrient overdose or deficiency; homemade diets are not complete and balanced unless a veterinary nutritionist has been consulted.

It is the veterinarian and pet parent's responsibility to discuss the issues of raw diets (dental and gastrointestinal trauma, nutritional benefit, pathogen risk) and whether such a diet is appropriate for the client. Pets that are immuno-compromised or are undergoing chemotherapy should not be fed raw diets. Moreover, households with immuno-compromised members should seriously weigh the risks and benefits of a raw pet food. Healthy dogs and cats, however, and pets with severe food allergies or those that require highly digestible diets may benefit greatly from a raw diet. When choosing raw diets, pet parents should contact and question manufacturers directly. This is not different from questioning kibble or can manufacturers. Currently, raw diets do not have specific regulations and are treated as any other animal feed, subject to FDA rules and state feed laws.

Commercial Raw Diets: Risk Assessment

Commercially prepared raw diets from large manufacturers with nationwide distribution typically utilize GMPs and quality ingredients; these diets pose little risk of pathogen transmission. Smaller, regional companies should be thoroughly investigated; these raw diets may pose a slightly elevated risk of pathogen transmission depending on manufacturer handling procedures and ingredient quality. The following discussion focuses on large commercial manufacturers of raw diets.

Helminths and Protozoans

Most diets are frozen at temperatures of -10°C or lower and are shipped and stored frozen. The average amount of time spent in the frozen state before consumption is about 18 days. It has been shown that most parasites (i.e., Toxoplasma, Trichinella,Tapeworms) cannot survive cold temperatures.^1-5 Similarly, the manner in which commercial raw diets are handled and processed also limits parasite risk. Tapeworms (Taenia, Echinococcus) and flukes that may occur in raw organs cannot be transmitted to pets because the lifecycle is broken.¹ Because brain, intestine, bladder, fetuses, and condemned carcasses harbor many parasites (i.e., Neospora, tapeworms, flukes), reputable commercial raw diets do not include these high risk parts. While raw fish is notorious for harboring a variety of parasites, there are few fish-based raw diets on the market and of those, grinding the muscle is sufficient to eliminate the risk of a pet contracting a parasite. Roundworms (i.e., Ascaris, Toxocara, and Baylisascaris) that inhabit the intestinal tract of mammals are not present in commercial diets. Wildlife passing eggs into the environment are of greater risk to pets.

Viruses and Prions

Viruses and prions are a minor concern in raw diets because commercial raw diets use only meat and organs from animals deemed fit for human consumption. Pseudorabies, associated with raw pork, is perhaps the most notable virus of concern. It is important to know that through vaccinations and culling, the US has successfully eradicated pseudorabies from all pork herds. Since 2003, no US-raised pig has tested positive for pseudorabies. Avian influenza is a worldwide concern and extends into the human food chain. In the US, surveillance systems and commercial flock testing ensures the poultry supply is safe and avian flu-free. Spongiform encephalopathies (i.e., BSE, CWD, Scrapie) may be contracted from infected animals when specified risk material (SRM) is consumed (tissue from the central nervous system of the ruminant). Most commercial raw diet manufacturers do not include SRM material in their diets. Moreover, lamb and venison (elk, deer) is typically purchased from Scrapie-free and CWD-free herds, respectively.

Bacteria (Focused on Human Health Risk)

All pet food may be contaminated with bacteria, both pathogenic and non-pathogenic strains. Pet foods that have been heat processed and considered "sterile" have been recalled due to pathogen contamination. The risk of pets contracting Tularemia (Francisella tularensis) from rabbit meat, Mycobacterium spp. from bovine organs, Anthrax (Bacillus anthracis) from sheep meat, Pseudomonas sp. from horse glandulars, and pathogenic strains of E. coli, Salmonella, Clostridium, Staphylococcus, Yersinia, Campylobacter, and Listeria is manageable when using commercial raw diets because of the source and quality of the meat. To illustrate, there are few documented cases of septicemia in pets fed raw diets. In one recent case, 2 cats died from Salmonellasepticemia after being fed a home-prepared raw diet.⁶ While this is a validated case of clinical salmonellosis due to diet, it appears to be a rare occurrence. Over 15 million pounds of commercial raw pet food is sold annually in the US. Despite the large number of dogs and cats consuming raw food, there are very few reports of sick pets and apparently no reports that link human illness with raw-fed pets. There have been no definite human illnesses linked to raw-fed pets despite the fact that approximately 50% of all pets share their owners' bed.⁷ Interestingly, pets are at greater risk of contracting disease from their human owners.⁸

Salmonellosis is a reportable disease; health officials and veterinarians have a legal responsibility to report human illness and probable source of infection. To date there is only one evidence based-CDC report of a dog/cat to human transmission of Salmonella⁹yet there are numerous Centers for Disease Control (CDC) reports detailing Salmonella transmission between reptile and child or rodent and child. Similarly, there are reports highlighting the potential danger of Salmonella and E. coli transmission at petting zoos. It is important to realize that pets, even those fed canned or dry food¹⁰ are at risk for bacterial septicemia and may be sub-clinical carriers. Feces from dogs fed conventional dry diets are rich in many bacterial pathogens.¹¹ Sanitation is critical. Along with proper handling of fecal material, food bowls should be stainless steel and scrubbed daily with bleach to remove any bio-film created by canned, raw, or dry food.¹²

Pathogen Risk: What We Know

There are relatively few scientific studies exploring the risks of raw diets and even fewer that have investigated the nutritional benefits of raw diets. The published papers discussing raw diets and pathogens describe findings from all 4 types of raw diets. Moreover, some of the papers are strictly reviews or opinions, not original research. Of those that are true scientific studies, a number of strongly worded "Letters to the Editor" resulted.^13-17 The following is a brief review of current literature on raw diets.

Stiver et al., 2003⁶

Two house cats were diagnosed with multi-organ septicemia following necropsy. Salmonella was found to be the culprit; the subtype in the food matched that from the cats. It was learned that the cats were fed a beef-based home prepared diet, not a commercial diet.

Strohmeyer et al., 2006¹⁸

This study evaluated the presence of bacteria and protozoa in commercial raw diets. Bacterial culture and polymerase chain reaction (PCR) was conducted on 240 raw diet samples and 20 dry/canned samples. Non-type specific E. coli was found in raw and dry/canned. Salmonella was found in raw but not dry/canned. PCR detected Cryptosporidium in raw and Campylobacter in canned. Authors concluded commercially prepared raw diets are a potential source of pathogens. This study did not feed the diets to dogs and therefore could not assess whether pets would shed pathogens. It is important to note Campylobacter was found in "sterile" diets.

Finley et al., 2007¹⁹

Dogs were fed Salmonella-positive raw diets or Salmonella-negative raw diets. Diets were purchased from pet stores and tested for Salmonella. None of the control dogs shed Salmonella. Of the dogs fed contaminated food, only 44% shed Salmonella; none showed clinical signs. Importantly, of the dogs shedding, not all shed the same serotype isolated from the food. The paper did not describe how the raw diet was handled, stored, or thawed prior to feeding.

Bagcigil et al., 2007²⁰

The degree of Salmonella shedding by100 dogs admitted to a European veterinary hospital or 100 dogs living in a crowded kennel was determined by a single rectal swab. Dogs showed no signs of salmonellosis and it was noted that they were fed "good quality food" that consisted of commercial food and table scraps. Results indicated Salmonella shedding was extremely low. It should be noted that rectal swabs were taken only once despite the intermittent nature of Salmonella shedding.

Morley et al., 2006²¹

Samples were taken from food, feces, and the environment at a greyhound breeding facility following Salmonella-related deaths of several puppies. Dogs were housed in outdoor dirt runs; fecal matter removed daily but runs were not disinfected. All dogs were fed a raw meat diet consisting of inedible meat thawed at room temperature for 24 hours. Food was provided ad libitum from stainless steel bowls cleaned only when new food was added. The facility lacked proper sanitation methods. Salmonella was isolated from many locations and insect vectors. This study clearly demonstrates the hazards that could occur when raw meat diets are not handled properly, husbandry practices are lax, and inferior meat from condemned or 4-D animals is used.

Weese et al., 2005²²

Commercially prepared and frozen raw diets were purchased and cultured for pathogens. The diets were thawed at room temperature before culturing. Several species of bacteria were detected. The raw diets were never fed to dogs to assess whether fecal shedding occurred. Meat quality was not specified. Furthermore, diets were not thawed in the refrigerator as is recommended.

Joffe and Schlesinger, 2002²³

After feeding a commercial dry or BARF diet for 2 months, food and feces were tested for Salmonella. Commercial dry food and dog feces were negative. Over 80% of BARF diets were positive for Salmonella but only 3 fecal samples were positive, and not always with the same serotype isolated from the corresponding diet. While they concluded that BARF is more likely to increase the risk of zoonosis, this study had several flaws: 1) clients made the diet and did not specify how it was handled, the meat quality, or the number of different batches of food, and 2) dog feces were sampled only once (Salmonella is shed intermittently).

Freeman and Michel, 2001²⁴

Three types of raw diets (BARF, Commercial, and Mix) were evaluated for nutritional adequacy and E. coli contamination. All failed to meet AAFCO nutritional guidelines. The Commercial was the most adequate and had a balanced calcium-phosphorus ratio. It was negative for E. coli. The BARF had major nutritional imbalances and was positive for E. coli. The Mix was nutritionally deficient but negative for E. coli. The authors did not feed these diets to dogs and conducted wet lab chemistry on a single sample of each diet. It was later found that several nutrient values were incorrectly reported; a correction was printed.

LeJeune and Hancock, 2001²⁵

This is a literature review of the public health concerns associated with raw diets (parasites, bacteria, etc). Authors assert that despite proper food handling, dogs fed raw meat may shed pathogens as subclinical carriers and represent a real risk to humans. They noted that there are several studies in which food and feces contained the same pathogen strain. Authors assumed raw pet food was made with low quality and less stringently regulated meat (condemned, 4-D, inedible offal).

Lewis et al., 2002²⁶

Following a Salmonella outbreak in zoo-captive carnivores, the zoo switched its feeding practices. Prevalence of shedding decreased to zero. It was determined that low quality raw meat was responsible for 94% of all the zoo's felids actively passing Salmonella. Previously, all felids were fed raw horsemeat and raw chicken (including condemned and 4-D animals) blended in a non-approved facility. The zoo switched to a raw horsemeat diet made in a USDA approved facility that banned 4-D and condemned animals. This study demonstrated that changes to meat quality without changes to husbandry practices are sufficient to reduce risk.

Conclusion

Home prepared raw diets pose a greater risk than commercially prepared raw diets because the source of the meat is often unknown. Meat quality, source, and processing are critical hazard points^2,21,26,27 that can be controlled or eliminated by purchasing commercially prepared raw frozen diets. Consumers need to use common sense when handling raw meat; many commercial raw diets have instructions printed directly on the bag of raw food.

Nutritional adequacy of home prepared diets will continue to be an issue. For pet parents wanting to feed raw diets, selecting a commercially prepared diet that has been through and passed AAFCO feeding trials is the healthiest option. Owners should contact the company and feel comfortable with the quality and nutritional adequacy of the brand--owners should not rely solely on blogs or similar websites to obtain company information or recommendations. Veterinarians should request a dietary history of each pet client in order to identify potential nutritional insufficiencies as it relates to the pets' medical condition.

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Alternative and Raw Food Diets: What Do We Know? (VT49)

Western Veterinary Conference 2012

Kara M. Burns, MS, MEd, LVT, VTS (Nutrition)
Academy of Veterinary Nutrition Technicians, Wamego, KS, USA

24026348

Every year in the US there are 76 million reported cases of food borne illness in people. Although the majority of these are self-limiting, 323,000 people are hospitalized and ~ 5,200 deaths are attributed to food borne illnesses each year. These figures are important because homemade and raw diets for pets are made with ingredients from the same food supply chain. In veterinary medicine few topics are associated with such strong opinions as the feeding of raw meat to dogs and cats. Both proponents and opponents are firmly entrenched in their views. Unfortunately, much of the information on both sides is based on anecdotes, theoretical concerns and personal opinion. Although objective information is increasing, this is still a field based largely on passion and opinion. This is an attempt to present a summary of the objective data for the nutritional adequacy, safety, and benefits of home prepared wellness and therapeutic diets and raw food diets.

Some health-conscious pet owners prefer preparing foods for their pets daily. Home preparation provides owners with a sense of involvement and allows them to select for or against specific ingredients. To maintain the nutritional adequacy and avoid contamination, owners must truly be committed to the long-term maintenance of proper hygiene and preparation methods. The meat and eggs produced for human consumption and used to prepare homemade pet foods are often contaminated with microbes.^1-3 Research indicates that many people are careless about cross-contamination during food preparation.⁴ The potential for food-borne illness in pets is reduced if owners use high-quality ingredients that have been stored properly, heat the foods to temperatures sufficient to destroy pathogens, and prepare only amounts that are readily consumed. Nutritional adequacy of home prepared diets is also of concern. Veterinary healthcare team members will inevitably work with pet owners that prefer alternative diets for their pets, and thus should be familiar with the objective data surrounding the nutritional adequacy, safety and benefits of home prepared wellness and therapeutic diets and raw food diets.

Raw Meat Diets

Raw meat feeding was popularized by Dr. Ian Billinghurst after the publication of his two books; Give Your Dog A Bone and The BARF Diet.^5,6 The latter book introduced the term "BARF", "Biologically Appropriate Raw Food' or "Bone And Raw Food", which has become widespread terminology. These books, which lack any scientific evidence, are based on the author's belief that commercial pet food is contributing to serious health problems in pets.

Many proponents have made very strong claims, including 'Dogs fed cooked and processed food and no bones will always develop a weakened immune system and poor dental health".⁷

Some have reported that raw diets are useful for the prevention or control of a wide range of conditions including chronic digestive, allergic and metabolic disease, bladder stones, feline lower urinary tract disease, intermittent vomiting or diarrhea, seborrhea sicca and recurrent ear infections.⁷ More specific claims of the 'disappearance' of many dental problems, many skin problems, ear infections, anal sac problems, arthritis, incontinence, keratoconjunctivitis sicca, diabetes and reproductive problems, and improvement of behavioral problems have also been made.⁸ An interesting claim is that: 'As a general rule, any genetic fault that your pet may have inherited will have minimum chance of expression when the BARF diet is fed.'⁸ There is frequent discussion about presumed negative effects of cooking, including destruction of vitamins, enzymes, 'anti-ageing factors', reducing protein value and availability, and production of 'foreign foods'.⁷

Proponents tend to dismiss infectious disease concerns, with statements such as 'Salmonella and Campylobacter are of absolutely no consequence to a healthy dog'.⁷ While Billinghurst claims that there are numerous feeding trials that show dogs fed raw foods are much healthier than dogs fed cooked foods, there is no objective evidence suggesting a beneficial health effect of feeding raw foods.

Nutritional adequacy, foreign body (i.e., bone) ingestion and infectious diseases are all cited as concerns regarding feeding raw foods. Infectious disease risks have received the most attention and is the area where more published research is currently available. As with any raw meat, there is the potential for contamination of raw meat-based pet foods. Salmonella spp has gathered the greatest attention as a possible risk; however Campylobacter, Clostridium difficile, C. perfringens, C. botulinum, E. coli, Yersinia enterocolitica, Listeria monocytogenes and enterotoxigenic Staphylococcus aureus are also of concern.^8-10 Recent studies also suggest that the potential exists for foodborne disease in pets eating raw meat but also disease in humans who are in contact with raw meat or the pet. Additionally pets fed raw meat are capable of contaminating the environment.

Bacterial contamination can be present in meat prior to slaughter in sick animals, however contamination occurs more commonly during slaughter, evisceration, processing and packaging. Ground meat, with its higher surface area to volume ratio and the need for additional processing, is more likely to be contaminated. The term 'human grade' has no regulatory definition and its use has been prohibited. However, since a significant portion of food sold for human consumption may be contaminated with a variety of pathogens, the use of 'human grade' meat does not indicate an absence of contamination. Once purchased, improper storage can result in bacterial growth. Some pathogens can grow at room temperature, while others can produce enterotoxins that cause disease.

In general, storage guidelines for raw meat are intended to prevent bacterial growth, not kill contaminants. Improper storage may create an environment which favors increases in bacterial numbers. As a result clinically irrelevant levels may become levels that can cause disease. Many organisms grow quickly at room temperature and sub-optimal refrigeration temperature highlighting the need for proper storage guidelines and concerns about growth in food residues in food bowls.¹¹

Ingestion of pathogens is the first step to developing disease. Many pathogens of concern, such as Salmonella spp, are dose dependent and large numbers are necessary to cause disease in most hosts, particularly if the host is otherwise healthy. However, some pathogens such as enterohemorrhagic E. coli can cause disease at very low doses and some individuals may be more susceptible.

Evidence Based Clinical Nutrition

Studies Documenting Nutritional Inadequacies

A 1992 survey of 200 homemade diets for both dogs and cats recommended by veterinarians for diagnosis and/or management of adverse food reactions found the majority to be nutritionally inadequate.¹² Another study compared 85 published home-cooked recipes for dogs and cats to AAFCO (American Association of Feed Control Officials) standards and found 86% inadequate in at least one nutrient, 55% deficient in protein and perhaps most importantly 77% of those diets deficient in taurine.¹³

Studies Documenting Contamination of Raw Foods

One study reported the isolation of a variety of serovars of Salmonella spp from 45% of raw meat samples.¹⁴ A more sensitive DNA probe detected Salmonella in 66% of samples. Salmonella spp were found in 56% of samples of meat fed to Greyhounds in another study.¹⁵ A small study reported isolation of Salmonella spp from 8/10 (80%) homemade raw meat diets.¹²

A study of commercial frozen raw meat diets in Ontario reported isolation of coliforms from all diets ranging from 3.5 x 10³ to 9.4 X 10⁶ CFU/g, Salmonella spp and Clostridium perfringens from 20% each, C. difficile from 4%, but no E. coli O157 or Campylobacterspp.¹¹ A larger Canadian study reported isolation of Salmonella spp from 22% of commercial frozen diets, spore forming bacteria from 100% and C. difficile from 8%. In this study, chicken diets were 4 times more likely to contain Salmonella spp than other types.¹⁶E. coli O157:H7 is a significant human pathogen with a very low infective dose, and it is has been identified in raw dog food.¹⁷

Studies Documenting Fecal Shedding of Pathogens

Joffe and Schlesinger 2002 reported isolation of Salmonella spp from 30% dogs fed raw chicken, but 1/10 dogs fed commercial diets.¹² Murphy reports that feeding raw meat or raw bones to dogs was associated with shedding of resistant E. coli.¹⁸ A recent study evaluated Salmonella colonization of dogs fed commercial raw dog food that was identified as naturally contaminated with Salmonella spp. Seven/16 (44%) dogs fed a single meal of contaminated raw meat shed Salmonella compared to 0/12 dogs fedSalmonella-free raw meat. No abnormal clinical signs developed in dogs that were shedding Salmonella, but they shed Salmonella for up to 11 days.¹⁹ Preliminary results of a prospective study of pathogen acquisition and shedding by dogs involved in therapeutic visitation programs has identified a high incidence of Salmonella shedding in raw meat-fed dogs, and a cluster of infected dogs that were fed meat from the same butcher. This group is of additional concern because of contact with hospitalized humans, who must be considered at higher risk of infection.¹³

Studies Documenting Clinical Infection

In one report, Salmonella spp were isolated from feces and food samples of Greyhounds with diarrhea, leading the authors to conclude that the diet is the primary vehicle for Salmonella infection in this breed.¹⁶ Fatal Salmonella Newport gastroenteritis and septicemia was reported in two cats fed a home-prepared raw-meat diet. An indistinguishable isolate was found in the diet, strongly suggesting it was the source.²⁰

Studies Documenting Environmental Contamination

A recent study of cleaning and disinfection practices for experimentally-inoculated food bowls reported Salmonella could be isolated from food bowls experimentally inoculated with a residue of Salmonella-containing raw meat for the entire 2 week study period. Further, this study reported that common cleaning and disinfection practices were inadequate for complete elimination of Salmonella from bowls.²¹

Studies Documenting Human Infection

The potential public health risks associated with handling and feeding raw diets may be of greater importance than disease in animals. One study has reported an outbreak of salmonellosis in people associated with dried-beef containing pet treats, indicating the potential for human disease from Salmonella-contaminated pet products.²²

Recommendations

There is no objective information indicating a health benefit of feeding raw diets. There is evidence to support concerns about raw diets with respect to nutritional adequacy, pathogen contamination, fecal shedding and environmental contamination. Veterinarians that recommend and / or sell raw meat diets should be consider their legal liability if either pet or human disease occurs and proper counseling of risks and infection control measures has not been performed and documented.

For those who wish to feed raw foods, careful consideration should be given to the individual circumstances. Raw food may be contraindicated in households where the implications of infection are particularly serious and situations where clinical infection is more likely to occur.

In humans, infants, the elderly and immunocompromised (disease or treatment) individuals are classified into these groups. The Centers for Disease Control and Prevention (CDC) guidelines for preventing opportunistic infections among high risk groups such as hematopoietic stem cell transplant recipients and HIV infected persons state that eggs, poultry and meat products fed to pets must be well cooked.^23,24 Similarly, feeding of raw meat is probably inappropriate in situations where animals in the household are likely at higher risk (i.e., breeding operations, immunocompromised pets).

Veterinarians and veterinary technicians should be responsible for carefully explaining household infection control practices to clients. Standard guidelines for handling raw meat and prevention of foodborne infections are available.²⁵ Hand hygiene is the most important general infection control practice. Hands should be thoroughly cleaned after handling raw meat. Raw meat should be stored so it will not come into contact with other food items. All items that contact the food should be disinfected after use. Cutting boards used for raw meat should not be used for anything else. Because many bacteria can grow quickly at room temperature, raw meat should not be thawed at room temperature or allowed to sit in bowls. Bowls should be cleaned shortly after feeding. Any remaining food should be removed; the bowl should be scrubbed to remove debris and then disinfected. High risk individuals should not have contact with food bowls. Water bowls should probably be treated with similar caution. Feces should be handled with care. Fecal contamination of the environment should be cleaned promptly, with hands washed thoroughly after contact with feces

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Raw Food Diets: The Dark Side

Atlantic Coast Veterinary Conference 2010

Anthony P. Carr, Dr. med. vet., DACVIM
Small Animal Clinical Sciences, Western College of Veterinary Medicine, Saskatoon, SK, Canada

20561421

Raw food diets have enjoyed some popularity, possibly even more so since the incidents with the contaminated dog and cat food. BARF diets (biologically appropriate raw foods) present a variety of problems, including that many are not well balanced. Of more concern is the zoonotic risk they represent.

Salmonellosis

Salmonellosis has received public attention on occasion. Most cases of this disease are acquired as a result of ingestion of contaminated food. Raw chicken and uncooked eggs are generally recognized as common sources of Salmonella infections in man. The risks of exotic pets, especially in regard to turtles have also been widely publicized. Another area that has received some media attention is rawhide chews which can be contaminated with Salmonella. Depending upon the source, a large percentage of rawhides and pig ears can harbor Salmonella. In one outbreak it was shown that contact with the treats or pets that consumed them was responsible for human salmonellosis.¹ Of 94 pig ear samples from retail outlets, 51% were harboring Salmonella. Salmonella was also found in other treats including beef hoof, braided chews and similar products. Of great concern were outbreaks of multidrug resistant Salmonella typhimurium in small animal facilities including an animal shelter and 2 small animal clinics in 1999.² In one veterinary clinic, the likely source of the infection was a kitten with diarrhea; 10 of 20 employees developed clinical signs. In another instance, one affected person was an employee and 2 were clients that had brought their cats to the clinic for treatment. After discharge, the cats developed diarrhea and the owners subsequently became ill. This obviously raises the specter of liability for the pet and owner's illness.

It certainly is not surprising that dogs can also harbor Salmonella species. Most recent studies have shown a prevalence of around 1 to 2 % in normal dogs and cats.^3,4 Percentages may be higher in animals with diarrhea. Very high prevalence had been found in racing sled dogs, where 69% of dogs without diarrhea were shedding Salmonella.⁵ In Greyhounds with diarrhea 61% were positive for Salmonella, in non-diarrheic dogs the percentage was 11%.⁶ The increased proportion of Salmonella positive animals in these dogs may relate to the stress of athletic performance or to their diets.

Raw meat can be a source of Salmonella infection in dogs. This has been shown in a variety of studies looking at athletic dogs such as Greyhounds and sled dogs that routinely receive uncooked meat as part of their diet.⁶ Recently, there has been considerable interest in raw diets for pet dogs, the most popular called BARF (biologically appropriate raw food). The internet is replete with sites that popularize this type of diet and its supposed health benefits. It does however mean that owners are routinely contaminating their environment with potentially infectious materials such as raw chicken. Dogs are not known to be especially clean eaters and it is highly likely that infectious organisms are disseminated throughout the home. In a recent study on a small number of dogs, 30% of dogs fed a BARF diet were shedding Salmonella, 80% of the food samples were positive.⁷ This has also been my personal experience where dogs fed BARF diets are positive for Salmonella (2 of 3 tested) even without clinical signs of diarrhea. Recent work has suggested that sterilizing food bowls is very difficult and under most conditions Salmonella can still be cultured (even after bleaching and use of a dishwasher high heat cycle).

Campylobacter

The prevalence of Campylobacter closely parallels that of Salmonella in cats, with approximately 1% harboring this infection.⁴ The prevalence in dogs is considerably higher in some studies where up to 28% of dogs are infected.³ Other studies however show the prevalence to also be around 1%.⁸ The majority of human cases are acquired by ingestion of contaminated food. The percentage of poultry with Campylobacter is higher than the percentage with Salmonella. There is the possibility of spread from dog or cat to man. The majority of dogs will not show clinical signs if infected.

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Raw Food Diets: Fact versus Fiction

ACVIM 2006

Ann Wortinger, LVT, VTS (ECC)
Belleville, MI, USA

18282310

Introduction

It is generally accepted that dogs were domesticated from wolves; the period of this evolution ranges from 10,000-135,000 years ago. Accordingly, some recent DNA research shows that this occurred in stages in different areas, not all dogs breeds came from the same wolf or from the same geographic area.¹ The primary ancestor of the domestic cat is believed to the African wild cat, Felis libyca. Domestication started for cats much later then it did for dogs, ~8,000 years ago with full domestication taking place only 4,000 years ago.² The time difference is reflective in what these animals were domesticated for, dogs were hunters, cats were vermin killers on the farms. As we evolved from a hunting society to a farming society, our needs changed also.

With this history in mind, we need to look at what food these animals have consumed since they joined us in our homes. Dogs did not continue to hunt and eat raw foods once domesticated; they primarily ate our leftovers and scraps. Since we have not consumed a raw food diet since fire was discovered, our dogs did not eat raw food either. Since cats were domesticated for their ability to control small vermin, they have continued to eat a raw food diet for a much longer period of time.

Myth: Raw food diets are nutritionally superior to processed diets, and is "what nature intended dogs and cats to eat".

There is no scientific evidence showing that raw food diets are nutritionally superior to processed foods. All processed foods are required to conform to AAFCO (American Association of Feed Control Officials) standards for sale in the United States. These standards can be met in one of two ways. The food can be "formulated" to meet AAFCO standards, or feeding trials can be done. Feeding trials are the preferred method of substantiating AAFCO certification.⁵ This takes into account not only nutrient content, but nutrient loss due to processing and digestibility.

Raw food diets overall are not marketed as "complete and balanced" and therefore not need to meet AAFCO standards. Some of the frozen diets however are marketed as "complete and balanced" and have AAFCO statements on the labels, but have not undergone feeding trials. The claim is that these diets are "complete and balanced" over a period of time, but not for each meal. There are three main types of raw food diets.

Commercially available complete raw food diets.

These diets are intended to be complete and balanced without the need for additional supplements. They are typically sold in frozen form.

Homemade complete raw food diets, many recipes for homemade raw food diets are available in books, article and on the Internet.

These diets expect the owner to balance the diets out in the long term as each meal is not in itself balanced.

Combination diets.

These consist of commercially available mixes of grains and supplements. This mix is in turn combined with raw meat.⁴

Granted, raw food diets may be nutritionally superior to some commercially processed foods. Those would be the poor quality foods that have not gone through feeding trials, use lower grade ingredients, and have high cereal contents. Feeding any premium quality food would show an improvement just due to the increased quality of the ingredients used.

Since raw food diets have not gone through feeding trials, it is difficult to know if they are nutritionally balanced or not. One study has been done looking at the nutrient content of a variety of raw food diets, both home prepared and commercially available. None of the diets studied were balanced, and all had nutrient deficiencies or excesses. These deficiencies and excesses may have been balanced out in the long term, but this is not guaranteed.⁴

Pet food manufacturers know what changes occur with their foods with the various processing methods, and supplement as needed to maintain optimum nutrient levels. As with any science, we continue to discover every day new ways to use diet to modulate various disease or conditions--and the manufacturers continue to change and improve their foods.

Myth: Domesticated species tolerate bacterial contamination in food without problems, even if they are pediatric, geriatric, or critically ill animals.

There is not scientific evidence to support this claim, and in fact three studies have found either bacterial contamination in the food or dishes, or death related to pathogenic bacteria directly related to the diet being fed.^4,5,6

The study looking at nutrient content of the diets also looked at microbial analyses. One of the five diets yielded growth of E. coli 0157:H7.⁴This strain of E coli has been connected to E. coli infection in people, and is one of the more pathogenic strains.

Another study presented in JAAHA reported two cats presenting for necropsy that died from septic Salmonellosis. In one of the cases it was directly traced back to the raw food diet fed. The two cases were 9 months apart in presentation, but from the same household. Healthy adult cats appear to have high immunological resistance to the development of clinical Salmonellosis. Cats that are immune compromised or otherwise ill would be at increased risk of infection due to contaminated food stuffs.⁵

Animals that are not sick themselves can also pose a public health concern due to shedding of bacteria into the environment. There are a number of bacteria that can be found on raw meat and transmitted to animals and subsequently to their owners or others in contact with the animal or their stool.

20-25% of poultry carcasses intended for human consumption test positive for Salmonella organisms, the raw meat used for feeding dogs is even more frequently contaminated. Most raw poultry is also contaminated with Campylobacter species, primarilyCampylobacter jejuni, so food borne infection is highly probable for dogs fed raw chicken.

Shiga toxic Escherichia coli strains are routinely isolated from fresh ground hamburger. Escherichia coli 0157 has been identified in dog feces.

Yersinia enterocolitica, can frequently be isolated from raw meat, especially pork. As much as 89% of the commercially available raw meats may be contaminated with this organism.

Numerous food-borne parasitic infections can also affect dogs and cats. Feeding raw fish can result in infection with a variety of organisms including Diphyllobothrium latum, the fish tapeworm; Opisthorchis tenuicollis, a trematode that infects the bile duct, pancreatic ducts and small intestines; Dioctophyme renale, the giant kidney worm; and Nanophyetus salmincola, the vector for Neorickettsia helminthoeca, the agent responsible for salmon poisoning in dogs.⁶

Dogs routinely fed raw meat are commonly infected with the protozoan Sarcocystis spp., and infected dogs may excrete sporocysts in their feces and contaminate the environment. Dogs can become infected with Toxocara canis and with the raccoon ascarid,Baylisascaris procyonis as a result of eating raw meat. Infected dogs can develop enteritis and shed infective eggs into the environment. In humans these two parasites cause visceral larval migrans. Dogs are also susceptible to infection with Trichinella spiraliswhose larvae in found encysted in meat. Undercooked or raw pork is occasionally contaminated with this parasite.⁶

Myth: Raw food diets improve the health of their pets.

The primary claim from raw food proponents is that this diet improves the health of their pets. While this is fairly nebulous and hard to prove, very few medical conditions can be directly traced back to nutrition.

On average a wolf in the wild only survives to 8 years old, wolves in captivity can survive up to 16 years. Most deaths are attributed to predation, disease and starvation. As Darwin showed us, life in the wild is survival of the fittest. An animal with many of the diseases we treat for commonly in small animal medicine would not survive in the wild. That, to our pets would be the benefit of domestication. Until fairly recently, we did not have the medical knowledge to treat these conditions either, but as human medicine progresses, so does veterinary medicine.

It would be presumptuous to think that the conditions that we see and treat our cats and dogs for do not exist in the wild, and that this is solely due to the diet they consume. Furthermore, what would be the hunting ability of many of our current breeds? Could a Persian administer a cervical bite to a mouse, or is their breeding induced malocclusion too severe to do this? What are the chances that a Yorkie would be able to catch and kill anything to eat, and considering the variety of foreign objects that a Labrador eats, would it be able to find the right food to kill and eat?

Myth: Uncooked food is more easily digested because it contains enzymes that cooking destroys.

Some nutrients are destroyed by heat, but not all heat-sensitive nutrients are eliminated during cooking. This is dependent on what the nutrient content of the food was initially and how the food is processed, stored and cooked.⁷

Heat can also affect proteins. Proteins can be "denatured". Their physical and chemical properties can be changed or altered. This happens with egg whites when they are cooked, the albumin becomes denatured and easier for the body to digest. Some proteins in meat also exist as enzymes, proponents of raw food diets contend that these enzymes become inactive when the meat is cooked. These proteins would also become inactive in the stomach when they meet up with the digestive enzymes. There are also other enzymes that are resistant to digestion (digestive enzymes) and may or may not be affected by stomach acid or heat from cooking. For the enzymes that are affected by heat, there is little evidence to suggest that they are more beneficial to animals that eat them raw.⁷

Due to the cellulose layer found in all plant based compounds, digestibility of these nutrients is difficult until the cellulose layer is broken down. This can be accomplished either through chewing, grinding of the food or cooking. Plant based materials are the primary source of carbohydrates for the body; these carbohydrates in turn are used for glucose production. If insufficient carbohydrates are available for energy, the body can also use glucogenic amino acids or glycerol from fats. If adequate dietary carbohydrates are not available, amino acids will be directed away from muscle growth, fetal growth and milk production to be used for glucose production.³

As carbohydrates are heated or cooked with water the starch contained within the cells undergoes a process called gelatinization. The greater the degree of gelatinization, the greater the degree of digestibility. The central nervous system and the red blood cells required glucose for their energy needs. Glucose consumed in excess of energy needs can be stored as glycogen. After glycogen stores are filled, any extra carbohydrates are converted into long-chain fatty acids and stored as fat.³

Conclusion

Since feeding trials have not been done on the majority of raw food diets, their nutrient content, digestibility and supplementation levels are for the most part unknown. By using raw meats, clients are leaving their pets and themselves open to bacterial and parasitic infection from possibly tainted meats. And there is no guarantee of improved health, what are the options in treating these pets?

First and foremost, do not ostracize these clients; most people opting to feed a raw food diet are conscientious owners looking to do the best thing for their pets. They, unfortunately, do not have a nutritionist in the kitchens. Most importantly, try to get them to cook the food being fed to their pet--this will at least address the bacterial and parasitic problems. Find out what they don't like about commercially available diets, if they are misinformed on any issues gently guide them in the right direction. If clients insist on continuing to feed raw food diets, or homemade cooked diets, recommend 2-4 yearly visits for complete physical exams and blood screens to detect any problems before they become severe.

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