It should be noted that no concrete evidence exists for a clear health benefit across the board for these conditions. However, from a gastrointestinal prospective, raw food has been
documented to be highly digestible and may lead to alterations in bacterial flora, both having potential benefits in modulation of enteropathies. Additionally, they are generally a single protein source, which could be beneficial for both allergic enteropathies and cutaneous adverse food reactions. Fatty acids provided in raw diets could result in improved coat quality, as both omega 3 and omega 6 fatty acid have dermatologic benefit. From a urinary prospective, idiopathic cystitis could theoretically be manipulated by increasing the water content within the food and reduction in stress of the cat (eg. palatability), factors shown to be important in its management. Urolithiasis could be influenced by changes in mineral composition of the diet, changes in water content and manipulation of urinary pH. Recent evidence suggests that changes in the microbiome (gut flora) could potentially influence systemic inflammation in some models suggesting potential benefits for inflammatory conditions. Dental hygiene could be influenced by direct abrasive effects of bone and the addition of oxtail (shown to reduce periodontal disease). Therefore, while the evidence is lacking, it is easy to see that dietary influences on disease expression is plausible.
It should be noted that the veterinarian could be held legally responsible for zoonotic or outbreaks within animal populations. The veterinarian and staff should be aware of this concern and should ensure proper client education.
Veterinarian's Checklist for Education
- Hands should be thoroughly cleaned after handling raw meat
- Raw meat not come into contact with other food items (during storage, handling, etc)
- All items that contact the food should be disinfected after use
- Use dedicated cutting boards for raw meat
- Remind owners tha bacteria can grow quickly at room temperature (don't allow food to sit)
- Bowls should be cleaned thoroughly, shortly after feeding
- Remove remaining food in the bowl (scrub debris, disinfect)
- Eliminate exposure of high risk individuals (bowls, etc.)
- Water bowls should be treated with similar caution
- Feces should be handled with care
- Fecal contamination of the environment should be picked up quickly
Much propaganda exists amongst the raw food advocates including concerns regarding commercial diets including the use of fillers (eg. Grains), the reduction in digestive enzymes from cooking process and the presence of "by-products". These are misinformed, uneducated statements that are either proven false or do not have the meaning that is being claimed.
Finally, raw food proponents also claim that it is more natural, as it is what is fed in the wild. It is important to note however, that many wild animals have a shorter lifespan than those in captivity suggesting that being more "natural" may actually be inferior.
On the other hand, the opposition to feeding raw food frequently cites the following:
Human health concerns
Excessive hormonal exposure (ie. thyroid hormone)
Bacterial contamination of food is a major concern as they can both produce endotoxins and exotoxins that could result in disease or dissemination of infectious agents into the environment. The most common concerns include The bacterial pathogens that represent a potential risk include Salmonella spp, Campylobacter, Clostridium difficile, C. perfringens, C. botulinum, E. coli, Yersinia enterocolitica, Listeria monocytogenes and enterotoxigenic Staphylococcus aureus. Salmonella and Clostridium spp.are the most commonly documented infectious agents in raw food, however, all have been documented. This is more of a concern with raw food due to the lack of cooking and ease of potential cross contamination even when the preparer maintains a high level of attention to detail. In addition to contamination at home, contamination of food that is out of the consumers control (eg. contamination during slaughter, processing, packaging and handling of food) exists.
Less commonly discussed infectious agents that could be present in raw food diets include viruses (eg. Pseudorabies, Influenza), prions (BSE, CWD, Scrapie), protozoa (Toxoplasma, Neospora, Diphyllobothrium latum, Sarcocystis spp.), trematodes (eg. Opisthorchis tenuicollis, Nanophyetus salmincola) and nematodes (Roundworms, Dioctophyme renale). Avoidance of certain tissues including brain, intestine, bladder, fetuses, and condemned carcasses harbor will reduce potential exposure to many of these organisms. Additionally, utilization of commercially available raw food diets that employ freezing will also aid in reducing some parasitic contamination.
The raw food enthusiast should be aware that storage of food in cold environments (eg. Refrigerators, freezers) do not kill bacteria, only slow bacterial growth. Therefore, minimization of contamination can be achieved with preparation of individual meals rather than "making a batch for the week". The general principles for reducing potential for contamination include the following:
Minimal pre-preparation of meals
Proper cleaning/removal of residues
Appropriate sanitation of utensils, bowls, etc.
Purchase of meat sources with minimal pre-processing (ie. ground beef)
Rapid discarding of residual food
Removing uneaten food from the bowl/dish
Consider commercially available raw vs. homemade
Helpful Websites: http://www.fsis.usda.gov/fact_sheets/safe_food_handling_fact_sheets/index.asp
From a clinician's perspective, bacterial gastroenterocolitis is uncommon from food related bacterial contamination in our small animals patients. However, it should be noted that higher levels of bacteria have been appreciated repeatedly in studies and the potential for disease always exists. Noting that disease expression has to do with level of exposure/contamination and host related factors (immunity, concurrent diseases, etc.) and may not be expressed phenotypically. Additionally, patients eating raw food have been shown to shed infectious agents to the environment with higher frequency than those not consuming raw food. This can act as a potential vector for zoonosis and companion animal infection. Particular concern exists in households with immunosuppressed individuals or animals, therefore raw food cannot be not recommended in these situations.
Concerns regarding infectious disease
Bacterial shedding of infectious agents in stool: environmental transmission ***
- Salmonella sp. ***
- C. perfringens, C. botulinum***
- Clostridium difficile,
- E. coli
- Yersinia enterocolitica
- Listeria monocytogenes
- Enterotoxigenic Staphylococcus aureus
- Campylobacter sp. ***
An additional concern regarding raw diets is the nutritional adequacies of the diets. Many of these diets have been shown to have nutritional inadequacies with a large percentage being deficient in at least on nutrient and commonly being inadequate in protein or essential amino acids, like taurine. The taurine deficiency in these diets is critical in some cats, as dilated cardiomyopathy has been documented in cats fed raw food exclusively. Additionally, some evidence suggests that taurine availability, even when provided in sufficient quantities, can be altered, leading to decreased plasma taurine levels.
Recently, documentation of hyperthyroidism in dogs has been documented in pets fed rawfood suggesting that potential exposure to exogenous thyroid hormone exists. Therefore, owners/veterinary community should note signs compatible with excess thyroid hormone and consider this on the differential diagnosis.
An additional factor found in raw diets that include bone is the potential for the bone to result in complications to the consumer including esophageal/intestinal obstruction, gastrointestinal perforation and/or gastroenteritis.
As stated above, commercially available raw food diets exist and may by "safer" than homemade diets as the manufacturers typically purchase meat from known sources, need to meet AAFCO standards, often provide instruct owners on packaging of proper handling/preparation (limiting contamination) and employ freezing practices that may kill some potentially pathogenic organisms. These diets will always be preferred to homemade diets for these reasons.
In addition to raw diets, other unconventional diets exist including: vegetarian and homemade diets. Vegetarian diets are not optimized for obligate carnivores like the feline species and may not be ideal for the canine, either. Several commercially available vegetarian diets exist however, they have not been evaluated over a long time period to appreciate health benefits or complications. Nutritional supplementation is likely necessary to meet all demands in the feline species (eg. retinol, cholecalciferol, taurine, and niacin). No proven health benefits exist for these diets at this time.
Homemade diets have become more common place over recent years for multiple reasons. Homemade diets can have potential advantages through reduction in preservatives, control of ingredients and the ability to tailor diets to the individual animal. However, they are very commonly shown to be nutritionally inadequate. While veterinary nutritionists are very capable of formulating a balanced homemade diet, they are uncommonly utilized as the majority of homemade diets are prepared by pet owners with little to no training and lack of understanding or validation of the "recipes" they prepare. These diets have been commonly shown to be commonly deficient in calcium, zinc, iron, linoleic acid, choline or other trace minerals/vitamins. Additionally, it is common to add supplements to these diets, which occasionally can lead to excessive concentrations of various minerals with vitamin A and D excess being documented most commonly. Supplementation of these diets may be inadequate as many veterinary supplements are designed to be fed with a concurrent commercially available diet, rather than homemade.
It is the author's opinion that all pet owners insisting on feeding an unconventional diet should consult a veterinary nutritionist for guidance and validation of the diet. Additionally, veterinary nutritionist can aid in manipulation of the diet to suit the needs of patient and their concurrent disease processes. Veterinary nutritionists can be contacted by contacting the American College of Veterinary Nutrition (www.acvn.org).
In conclusion, many dietary options are available to pet owners including home cooked, raw and vegetarian based diets. Little to no scientific evidence exists to date supporting these diets either as being nutritionally optimal or providing any added benefits to the pet. Additionally, many factors exist that could pose a threat to an animals health. These diets cannot be wholeheartedly recommended at this time but the author maintains an open mind to potential benefits that these diets may have within an individual patient. If these diets are to be fed, utilization of a veterinary nutritionist for consultation regarding the formulation of an individualized diet and/or evaluation of an existing diet.
The author would like to point out that if benefits exist, they are likely to occur in individual patients and not within a population. The individual patient is critical to the veterinarian where pet owners seek a resolution to a problem. It is unlikely that the health benefits would be noted across a population when compared to a control group. Additionally, many of these conditions noted above may be modified with dietary intervention in general, both commercially processed or alternative diets.