Laurie Goldstein, CFA Analyst
Letter to the AVMA, 3 August 2012 (Posted with permission.)
The AVMA Facts page states, “This proposed policy is about mitigating public health risks, not about restricting or banning any products. Our policies are intended to present the scientific facts…”
I fear that all that will be achieved in adopting this policy is to further alienate raw feeders from their pets’ health care providers with the focus on pathogen avoidance as opposed to methods of proper hygiene. How can that possibly be in the pets’ or the public’s best interest?
It also seems that the body of literature considered for this proposed policy is lacking. The issue of pet-human transmission does not appear to have been considered; the fact that our pets irrespective of diet are already carriers of many pathogens does not appear to have been considered.
The risk of pet-human transmission. As to the hypothesis that our raw fed pets are a reservoir for transmitting salmonella to humans, there are studies that call this into question. After examining canine zoonoses and their risk to man Baxter and Leck  state that direct canine-human transmission has occurred in a relatively few cases. Pelzer (1989) states that although salmonella has been isolated from dogs, it is difficult to assess the risk of humans acquiring infections because the infective dose is difficult to define, and in most cases the number of organisms isolated from the animals is not provided. Finley 2006, a reference piece for the proposed Policy, indicates “no confirmed cases of human salmonellosis have been associated with these diets.” Yet there have been 128 confirmed cases of human salmonellosis associated with dry pet foods (CDC 2012, AVMA Aug 9 2010).
In fact, our dogs and cats are already carriers of Salmonella, E. coli, and other pathogens. “The intestinal carriage of Salmonella by dogs and cats is more common than the prevalence of clinical disease, with numerous serovars being isolated from each animal species. Prevalence of isolation of Salmonella spp from feces of healthy dogs is reported to be between 1 and 36%, and from healthy cats between 1 and 18%. (Sanchez 2002).
Beutin (1993) found verotoxin producing e. coli in 4.8% of apparently healthy dogs and Dahlinger (1997) cultured various types of bacteria, including some forms of e. coli and salmonella from the lymph nodes of 52% of apparently healthy dogs brought in for elective spays.
If the AVMA wants to protect Public Health, utilizing the logic employed as outlined in the proposed policy and this follow-on “Facts” clarification, combined with the studies referenced here, the AVMA ought to create an official policy recommending that the elderly, those families with young children, and immune-compromised individuals should not own pets.
Sources of pathogens. While undercooked and raw meat is sometimes implicated in food poisoning cases, there have been an enormous number of cases of salmonella and e. coli reported from fruits and vegetables. Bean sprouts have been linked to many outbreaks of food poisoning, as have melons, salads, and apple cider (Health Canada, 2002, and USDA 1995) and almonds (Chan 2002 and Outbreak of Salmonella Serotype Enteritidis Infections Associated with Raw Almonds). In other words, while raw meat is a risk, so is almost ANY uncooked food. Galton et. al found that infections in their study were in part “either derived from common sources, spread from animal to man or possibly the reverse,” and Mackel et al suggest that the instances of infection also relate to the numerous reservoirs of Salmonella in both human and animal environments.
There are also critical problems with at least one of the reference studies used in the development of the proposed Policy.
Joffe & Schlesinger 2002.
“[Joffe] proposes that dogs fed a raw meat diet are a “public health concern.” Looking objectively at his methods and results fail to prove this to be the case. His study used 10 client owned raw fed dogs and 10 client owned dogs fed a dry food diet as controls. One meal-sized food sample and one stool sample were collected from each dog and tested for salmonella. The owners were responsible for the collection of the samples and as is stated in the paper “were aware of the purpose of the study prior to collection.” This alone is questionable and can create bias. Controlled scientific studies should be set up so that they are blind to the participants in order to prevent their influence on the results. Nowhere in the paper does it mention control measures surrounding feeding (including, but not specific to sanitation), storage of food, collection procedures or sample handling (temperature regulation, time between collection and testing). There is also no information given with regards to the subjects (age, breed, and/or clinical history). Were any of these dogs previously treated for the presence of salmonella in their stool prior to the onset of the study? Were any other environmental exposures considered as the source of the salmonella (especially in the cultures that did not directly reflect the bacteria seen in the food)?
“The …conclusions drawn … do not necessarily fit with the breakdown of the facts. In fact Joffe helps to prove that dogs can deal with salmonella in their system. He states that 80% of the raw food samples tested positive for salmonella. Of those eight dogs two of them showed salmonella in their stool, only one of which was the same serovar that was present in the food. How can he then dismiss the suggestion that dogs fed infected food do not necessarily shed salmonella in their stool? Interestingly none of the dogs were reported to show clinical symptoms of Salmonellosis even though they were fed food that contained the bacterium. This is further supported by Ettinger and Feldman  who state that “isolation from gastrointestinal tract or its secretions does not indicate that the organisms are causing clinical disease.” (New, L (n.d.)).
Schlesinger and Joffe 2011, “Raw food diets in companion animals: A critical review.”
In the discussion for evidence of infectious disease risk to pets or humans sharing the same environment (in animals being fed raw food), the authors found no “Level 1” evidence. (“Level 1 studies include systematic reviews of multiple studies which have limited variation in their results, randomized controlled clinical trials (multiple), or an individual randomized trial with narrow confidence interval (very little if any overlap between groups). Also included in this group would be an “all or none” study where all patients died before treatment was available, but some now survive or some died before and now all survive with the treatment. Level 2 studies are systematic reviews of cohort studies with consistent results or individual cohort studies, including lower quality randomized clinical trials (< 80% follow-up). Level 3 studies include systematic reviews of case control studies with consistent results or individual case-control studies. Level 4 studies are a case series or poor-quality cohort and case-control studies. Level 5 studies include expert opinion without explicit critical appraisal; or the conclusions are based on physiological research or principles.”)
The bulk of the infectious disease risk-related studies are based on pet food/raw meat sampling. We know that proper handling of raw meat mitigates the risk in human transmission of bacteria.
Stiver et al. 2003 (Identified as a “Level 5” study in Schlesinger and Joffe 2011.)
- 1) Proper handling and storage of raw meat products should minimize Public Health risk of pathogens;
2) As outlined above, pets exposed to the pathogens infrequently develop illness associated with the pathogens;
3) As outlined above, despite being exposed to the bacteria via food, our pets do not necessarily shed the bacteria in their feces (for instance, Joffe 2002, where 80% of raw chicken diets were culture positive for Salmonella serovars, yet just 25% of the stool samples of the raw chicken eaters were also positive);
4) Dry pet food already is a proven source of pet-human transmission of pathogens, yet the AVMA addresses the problem with safe handling suggestions;
5) Our pets are already carriers of numerous pathogens;
6) The source of the pathogens in animal-human transmission is generally proved to be feces (Morse 1975, Pelzer 1989, Sanchez 2002)
It would seem that as regards raw feeding of pets, the primary concern is one of hygiene management, not pathogen avoidance.
Thank you for your consideration of public input.
Laurie D. Goldstein, C.F.A.
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AVMA 2010. Public Health: “Frequently Asked Questions about Dry Pet Foods and Salmonella.”, Aug 9, 2010 (accessed July 21, 2012).
Baxter DN and Leck I (1984). “The Deleterious Effects of Dogs on Human Health: 2. Canine Zoonoses.” Community Medicine 6:185-197.
Beutin L, Geier D, Steinruck H, Zimmermann S, Scheutz F. (1993). “Prevalence and some properties of verotoxin (Shiga-like toxin)-producing Escherichia coli in seven different species of healthy domestic animals,” Jour Clin Microbiology, 31(9):2483-8.
CDC 2012. “Multistate Outbreak of Human Salmonella Infantis Infections Linked to Dry Dog Food (Final Update)” (accessed July 21, 2012).
Chan ES, Aramini J, Ciebin B, et al. (2002). “Natural or raw almonds and an outbreak of a rare phage type of Salmonella enteritidis infection,” Canadian Communicable Diseases Report 28(12):97-99.
Dahlinger J, Marks SL and Hirsch DC (1997). “Prevalence and identity of translocating bacteria in healthy dogs,” J Vet Int Med 11(6):319-322.
Ettinger SJ and Feldman EC (1995). “Textbook of Veterinary Internal Medicine 4th Edition.” Harcourt Brace. Pp 336-368.
Finley R, Reid-Smith R, Weese JS, et al. “Human health implications of Salmonella-contaminated natural pet treats and raw pet food,” Clin Infect Dis 42:686-691.
Galton MM, Scatterday JE and Hardy AV (1952). “Salmonellosis in Dogs I: Bacteriological, Epdiemiological and Clinical Considerations. J Infect Dis 1952; 91:1-5.
Health Canada (2002). “Risks associated with sprouts.”
Joffe DJ and Schlesinger DP (2002). “Preliminary Assessment of the Risk of Salmonella Infection in Dogs Fed Raw Chicken Diets,” Can Vet J 43:441-442.
Mackel DC, Galton MM, Gray H and Hardy AV. (1952). “Salmonellosis in Dogs IV: Prevalence in Normal Dogs and Their Contacts,” J Infect Dis 91:15-18.
New, L. (n.d.). “Salmonella and the raw diet,” Mountain Dog Food website (accessed July 21, 2012).
Pelzer KD. (1989). “Salmonellosis.” JAVMA 195:456-463.
Sanchez S, Hofacre CL, Lee MD, Jaurer JJ and Doyle MP. (2002). “Animal Sources of Salmonellosis in Humans,” JAVMA 221:492-497.
Stiver SL, Frazier KS, Mauel MJ et al. “Septicemic salmonellosis in two cats fed a raw-meat diet,” J Am Anim Hosp Assoc 39:538-542.
USDA (1995). “An outbreak of E. coli O157:H7 How could it happen?” Food Safety and Inspection Service Flyer, July 1995
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Created 09/13/12; Updated 08/11/14