Wednesday, March 12, 2008

It's A Dog's Breakfast - Part 2: Common Misconceptions

It’s time to set the record straight on some of the most common rationalizations used by people to justify the safety of feeding raw meat and poultry to their dogs.


Misconception #1. A dog’s stomach acid is stronger than a human’s. Therefore, all harmful bacteria will be killed in the dog’s stomach.

Stomach acid is an important defense against food-borne infection. The normal stomach pH* in humans while fasting (that is, with no food in the stomach) is approximately 2. Stomach pH rises (becomes less acid) for a period of time after a meal, because the stomach acid is diluted and buffered by food, then falls again.

The stomach’s digestive juices, which contain a combination of hydrochloric acid and the enzyme pepsin, will kill bacteria within 15 minutes when the pH in the stomach is lower (more acid) than 3. But if the pH rises above 4 for any reason, bacteria can survive – and even multiply – in the stomach.

The pH of digestive juices in the empty canine stomach – as in the human stomach – is approximately 2 at its most acid. As with humans, feeding alters the pH in a dog’s stomach, causing it to shift between strong acid and weak acid or even neutral conditions. But there is one difference.

In dogs, some of the contents of the small intestine are “burped” back into the empty stomach from time to time. This periodic “burp” raises the dog’s stomach pH to nearly 7 (the neutral point) – an ideal pH for bacteria to multiply.

Think about it. Dogs carry bacteria in their intestines, and dog poop is full of bacteria. There is only one way for bacteria to get into the intestines, and that is via the dog’s mouth and stomach.

*Acidity is measured by pH, which ranges over a scale of zero to 14, with zero being the most acid, 14 being the most alkaline, and 7 being exactly neutral.


Misconception #2. A dog’s intestinal tract is short. Stuff passes through too fast for bacteria to take hold.

The essential first step to infection - attachment to the cells that line the intestine wall - is very rapid. Salmonella and other pathogens can attach irreversibly to a susceptible cell immediately upon contact. It doesn’t matter how quickly the food passes through an animal’s intestine. Once attached to its target cell, the pathogen will stick like Krazy Glue and invade the cell at its leisure - usually, within one hour after adhering to the cell.


Misconception #3. A dog’s saliva contains lysozyme, an enzyme that destroys bacteria. Therefore, the bacteria get killed before they are swallowed.

Dog saliva and human saliva both contain lysozyme, an antibacterial enzyme, which is also present in some other body fluids, including tears.

Bacteria are divided into two major groupings – Gram-positive and Gram-negative – based on the chemical structure of their cell walls. Lysozyme destroys the cell walls of Gram-positive bacteria, but cannot harm Gram-negative bacteria, such as Salmonella, E. coli and Campylobacter.


Misconception #4. Dogs don’t get sick from bacteria and, therefore, can’t infect their human companions.

Dog may be less susceptible than humans to becoming sick from Salmonella, but they are not immune. And, just like Typhoid Mary, apparently healthy dogs can shed Salmonella in their feces. Furthermore, Salmonella isn’t the only pathogenic microbe that can infect dogs. Campylobacter, which is prevalent in raw poultry, can also be carried by dogs. Parasites such as Giardia can be spread from dogs to humans, too. I'll provide specific examples in Part 3 of this series.


Sorting through conflicting statements about health and safety issues can be both confusing and frustrating, especially when those statements are not backed up by independent scientific evidence. If you’d like to delve more deeply into the technical details, the links I’ve provided will give you a place to start.


Watch for Part 3 of this series, “Getting Down To Cases”, which will appear on Friday, March 14th.

26 comments:

  1. Is it possible for raw fed dogs and their owners to become less susceptible to certain bacterias because they are exposed to it and theoretically 'fight' it off more than kibble fed dogs and owners would,making the risk less as time goes on? Also I have read that kibble fed dogs feces contain salmonella also, not just raw fed dogs-any info on that? Does it really matter either way if you wash hands after picking up ANY feces, raw or kibble fed?

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  2. Anonymous is correct - kibble fed dogs can contract salmonella from their food. One of the many recent pet food scares was due to this issue. The media mentioned many times that this was a danger to humans. Anonymous is also correct that proper hand washing should be practiced after cleaning up dog waste. Finally, pets can pick up many "yuckies" like giardia, worms, and/or bacteria from sources other than a raw diet. If these problems could be avoided by simply avoiding raw diets it would be the first thing vets mentioned.

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  4. The information on this blog seems like vested interest fear-mongering to me. I have fed raw to my dogs for years and have found only benefits to my dog's health. I was so glad that I was not feeding processed pet food to my dog during the 2006-2006 recalls. I still am. If you want to split hairs over the 'science' of raw-feeding, be my guest.

    However, it would be a politcal mistake for the FDA to increase regulations upon the raw pet food industry such as requiring irradiation of the food. This would benefit only the manufacturers of such equipment and processed pet food manufacturers.

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  5. So, how come dogs eat poop (theirs and other animals) and do not seem to be adversely affected by the nasty habit? Feces as we all know is loaded wth all kinds of pathogens. My brother's dog would eat their cat's poop whenever he could - and that dog has never come down with any GI upset! And he is a small dog.

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  6. So, why is it many dogs eat poop (their own and other animals') and do not suffer any adverse effects? I don't think ou need to convence anybody that feces contain a lot of pathogens. My brother's dog is a case in point. This small dog eats his and the cat's poop as often as he could get away with it - and yet, has never suffered so much as a tummy ache from the nasty habit. This dog is presented to the vet only for his vaccines.

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  7. "And, just like Typhoid Mary, apparently healthy dogs can shed Salmonella in their feces. Furthermore, Salmonella isn’t the only pathogenic microbe that can infect dogs. Campylobacter, which is prevalent in raw poultry, can also be carried by dogs. Parasites such as Giardia can be spread from dogs to humans, too. I'll provide specific examples in Part 3 of this series."
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    I just noticed this and are you saying dogs that are raw-fed are 'unclean'? This reminds me of what some radical religious sects teach their followers about dogs in general.

    I think it is very irresponsible to compare raw-fed dogs to Typhoid Mary! This could panic the public. I just read about a foreign government causing many domestic cats to be abandoned because they spread an unfounded fear that they carry SARS.

    What is the purpose in portraying raw-fed pets as 'unclean' or dangerously contagious? Do you have any valid stats that show that raw-fed pets are more of a public health menance than pets fed processed foods?

    I hope you will rethink the wisdom of your next installment.

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  8. I can't find ANY research including the CDC that supports what you are saying. The only thing that supports what you are saying is the billions of dollars spent on commercial kibble every year by the public.

    The CDC lists all cases of salmonella contamination as ingested or food born, unless feces is ingested it seems raw feeding is an unlikely source. When 80% of the human food supply contains salmonella, listeria, giardia, and other pathogens it seems the problem is with the FDA and the human food supply, not dogs getting raw food.

    Again I see no, none, any support for your claims on any reputable national/govenerment sites.

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  9. Would you name your research sources please? I can't find any data that supports what you've written.

    See article dry food recall contaminated with salmonella [L=http://www.fda.gov/oc/po/firmrecalls/mars08_07.html]http://www.fda.gov/oc/po/firmrecalls/mars08_07.html[/L] in 2007

    Another recall of salmonella contaminated dry dog food [L=http://www.fda.gov/oc/po/firmrecalls/mars208_07.html]http://www.fda.gov/oc/po/firmrecalls/mars208_07.html[/L] in 2007

    It seems much of the salmonella contamination comes from people handling pig's ears and rawhide given as treats and from feeding human food, also the above kibble food. Not raw fed dogs. I've been unable to find a single reference to a raw fed dog relating to a human infection.

    The dogs sited as carrying salmonella (about 27%) have no statistics given on diet type raw or otherwise. And the transmission vector is fecal/oral. The human food supply has about 80% contamination and the bacteria is ubiquitous not from a single food source. It seems this topic is barking up the wrong tree. DNA testing of dogs and humans rarely finds the same strains in people as in their animals except where both ingested the same contaminated food source. This is consistent back to 1978 as far as I can tell.

    I find the below very interesting

    Here’s what the Merck Veterinary Manual says about Salmonella in pets:
    “Many dogs and cats are asymptomatic carriers of Salmonellae. Clinical disease is uncommon, but when it is seen, it is often associated with hospitalization, another infection or debilitating condition in adults, or exposure to large numbers of the bacteria in puppies and kittens.” 2

    To translate: Many dogs and cats carry Salmonella in their systems (as evidenced by the presence of Salmonella in their feces), but they rarely become ill. It is just a natural part of what lives in their GI systems. When illness does occur it is usually associated with an already ill animal who is already immune-compromised. Illness may also occur when young animals are exposed to very high numbers of the bacteria. This might happen if a puppy finds and licks the inside of an outdoor garbage can that has never been washed and is teeming with bacteria.

    Research indicates that approximately 36 percent of healthy dogs and 17 percent of healthy cats carry Salmonella in their digestive tract.3 The American Veterinary Medical Association (AVMA) agrees with these numbers.4 It is interesting to note that these numbers are based on kibble-fed dogs – which means that Salmonella is a natural part of life for our pets regardless of what they are eating.

    The resistance to illness in dogs from Salmonella is apparent in a study of raw-fed dogs in Canada. In that study 16 dogs were deliberately fed commercial raw diets contaminated with Salmonella. None of those 16 dogs became ill. Additionally, only 7 of those 16 dogs shed Salmonella in their feces.5 While it was not further studied, one might speculate that the 9 dogs who ate Salmonella-contaminated food but did not shed it in their feces effectively neutralized the bacteria.

    Even the FDA, in the FDA Consumer magazine, acknowledges that healthy pets rarely become ill from Salmonella contamination.6
    ---------------------------------------------------------------------------

    From JAVMA
    The CDC report approximately 40,000 confirmed cases of salmonellosis annually.1 Poultry, meat products, and eggs are most commonly identified as food sources responsible for outbreaks of salmonellosis; however, many other foodstuffs such as ice cream, vegetables and fruits, breakfast cereal, milk, juices, herbs, and spices have also been vehicles of large outbreaks.
    ----------------------------------------------------------------------------

    I set about to find support for what you are saying because I am concerned having been infected by salmonella twice from contaminated food traced to a multiple outbreak both times. The proof just isn't there; even for a biased eye the stats don't support. It is possible to catch salmonella from your dog if you eat his poo or contaminated food from his mouth, there has never been a saliva transmitted case I can find that was proven with DNA. It seems this chance is so remote for direct transmission that 3/100 ths of one percent were suspected but not proven transmitted to humans in the only study of size I could find. This compared to 8/10ths of all human food contaminated and no proven cases of human to human transmission.

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  10. Why is this a blog where your previous book was a peer reviewed publication? Those reviews seemed to indicated the writing was a novelized version leaving the sensationized idea that the food industry was out to get the consumer. It sounded like the brave researcher versus the world type of thing Jean Auel would write. This blog appears the same in sensationalizing fear among the raw feeding public. Again the lack of references as in your previous book are lacking and I frankly find little or nothing that supports your claims ANYWHERE reputatble including the NEJM. I guess that is what blogs ARE about though. I strongly suggest all raw feeders do their OWN research before changing to commercial food which is ALSO a huge source of salmonella and chemicals to kill the pathogens it contains. What are you really recommending it is NOT obvious. Should we not have pets or not feed them or what? I don't feel critical either way but this presentation does seem like fearmongering for publicity.

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  12. I shall be very happy to respond to the people who have taken the time to comment on my blog series. I prefer to wait until all five parts of the series are posted, so that I can consolidate the comments and responses in one or more follow-up posts. This is to avoid repetition.

    I will respond to one question though - regarding book vs. blog.

    I was invited by my publisher to write one or more additional books, and I might yet do so. But I find that there is a very frustrating delay involved. It took three years to write and revise my food safety book. I chose to write a blog in order to have a more immediate impact.

    It is my desire to inform, not sensationalize. Even though a blog, by its very nature is not peer-reviewed (which means independent review by experts in the field prior to publication, by the way), I am trying to document this blog as though it would be subject to peer review.

    Please continue to read and comment on the remaining parts of this series. I promise that I shall respond in an organized and documented fashion to the best of my ability.

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  15. Ms Entis what you are saying about giardia passing to humans also seems unsubstantiated unless you have other sources. The strains found in humans and animals have not been proven to be the same.

    Early in 1995, the kennel population of more than 100 dogs at the Guide Dogs for the Blind Association's Midlands Regional Centre in Leamington Spa was hit by an unusually severe outbreak of diarrhoea. The cause turned out to be an infection of the intestine by a commonly-occuring, single celled organism - or protozan known as Giardia. A combined treatment and disinfection strategy was then introduced that brought the infection under control.

    Maggie Fisher, a veterinary surgeon with a special interest in parasitology, was called in to help deal with the Giardia outbreak, and in the following paper she describes the infection and how it can be treated and controlled

    The division of Giardia into groups according to species is still somewhat confused; the organisms that infect mammals look very similar but it remains unclear to what extent they form one or a number of species. It is for this reason that, while Giardia infection in some mammals, including dogs, is suspected of being infectious to man (ie: a zoonosis), it has not been conclusively shown that the species in, for example, dogs and man is the same.

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  16. Another research case of raw fed dogs NOT spreading salmonella to their human feeders. No known cases of raw feeders catching salmonella. Though treats and kibble are often sources of salmonella once again.


    Finley R, Reid-Smith R, Weese JS.
    Foodborne, Waterborne, and Zoonotic Infections Division, Public Health Agency of Canada, Guelph, Ontario, Canada. Rita_Finley@phac-aspc.gc.ca

    Human salmonellosis occurs mainly as a result of handling or consuming contaminated food products, with a small percentage of cases being related to other, less well-defined exposures, such as contact with companion animals and natural pet treats. The increasing popularity of raw food diets for companion animals is another potential pet-associated source of Salmonella organisms; however, no confirmed cases of human salmonellosis have been associated with these diets. Pets that consume contaminated pet treats and raw food diets can be colonized with Salmonella organisms without exhibiting clinical signs, making them a possible hidden source of contamination in the household. Pet owners can reduce their risk of acquiring Salmonella organisms by not feeding natural pet treats and raw food diets to their pets, whereas individuals who investigate cases of salmonellosis or interpret surveillance data should be aware of these possible sources of Salmonella organisms.

    PMID: 16447116 [PubMed - indexed for MEDLINE]

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  17. Another research case of raw fed dogs NOT spreading salmonella to their human feeders. No known cases of raw feeders catching salmonella. Though treats and kibble are often sources of salmonella once again.


    Finley R, Reid-Smith R, Weese JS.
    Foodborne, Waterborne, and Zoonotic Infections Division, Public Health Agency of Canada, Guelph, Ontario, Canada. Rita_Finley@phac-aspc.gc.ca

    Human salmonellosis occurs mainly as a result of handling or consuming contaminated food products, with a small percentage of cases being related to other, less well-defined exposures, such as contact with companion animals and natural pet treats. The increasing popularity of raw food diets for companion animals is another potential pet-associated source of Salmonella organisms; however, no confirmed cases of human salmonellosis have been associated with these diets. Pets that consume contaminated pet treats and raw food diets can be colonized with Salmonella organisms without exhibiting clinical signs, making them a possible hidden source of contamination in the household. Pet owners can reduce their risk of acquiring Salmonella organisms by not feeding natural pet treats and raw food diets to their pets, whereas individuals who investigate cases of salmonellosis or interpret surveillance data should be aware of these possible sources of Salmonella organisms.

    PMID: 16447116 [PubMed - indexed for MEDLINE]

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  18. About Giardia.

    Your 1995 reference is a bit out of date. Please see the following:

    http://www.ncbi.nlm.nih.gov/pubmed/15940523?ordinalpos=16&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_RVDocSum
    "In this study, genotype A was associated with samples from children and dogs, and, therefore, we could infer zoonotic transmission as a way of getting the disease."

    http://www.ncbi.nlm.nih.gov/pubmed/15856905?ordinalpos=17&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_RVDocSum
    "The presence of cysts of the A1 and A3 genotypes in isolates from pet dogs is consistent with their role as reservoirs for human infection, although further studies are needed to confirm the occurrence of zoonotic transmission.

    http://www.ncbi.nlm.nih.gov/pubmed/15567577?ordinalpos=21&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_RVDocSum
    The greatest risk of zoonotic transmission appears to be from companion animals such as dogs and cats, although further studies are required in different endemic foci in order to determine the frequency of such transmission.

    http://www.ncbi.nlm.nih.gov/pubmed/12928889?ordinalpos=29&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_RVDocSum
    The zoonotic potential of canine Giardia was also investigated by characterising Giardia duodenalis recovered from humans and dogs living in the same locality and households, at three different loci. Phylogenetic and epidemiological analysis provided compelling evidence to support the zoonotic transmission of canine Giardia.


    Unfortunately, I can't post a link to the full articles, as these are by paid subscription only. I shall, however, attempt to obtain an electronic copy from the authors and, if successful, will share the articles by email on request.

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  19. Another research case of raw fed dogs NOT spreading salmonella to their human feeders. No known cases of raw feeders catching salmonella. Though treats and kibble are often sources of salmonella once again.


    Finley R, Reid-Smith R, Weese JS.
    Foodborne, Waterborne, and Zoonotic Infections Division, Public Health Agency of Canada, Guelph, Ontario, Canada. Rita_Finley@phac-aspc.gc.ca

    Human salmonellosis occurs mainly as a result of handling or consuming contaminated food products, with a small percentage of cases being related to other, less well-defined exposures, such as contact with companion animals and natural pet treats. The increasing popularity of raw food diets for companion animals is another potential pet-associated source of Salmonella organisms; however, no confirmed cases of human salmonellosis have been associated with these diets. Pets that consume contaminated pet treats and raw food diets can be colonized with Salmonella organisms without exhibiting clinical signs, making them a possible hidden source of contamination in the household. Pet owners can reduce their risk of acquiring Salmonella organisms by not feeding natural pet treats and raw food diets to their pets, whereas individuals who investigate cases of salmonellosis or interpret surveillance data should be aware of these possible sources of Salmonella organisms.

    PMID: 16447116 [PubMed - indexed for MEDLINE]

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  20. Here is a link to the full text of the article mentioned in the most recent comment posted by Anonymous.

    http://www.journals.uchicago.edu/doi/full/10.1086/500211

    I encourage everyone to read it in full and draw their own conclusions. The pet treats mentioned in the article are NOT kibble - they are natural (and not cooked or sterilized) treats, including bully sticks, pig ears, etc.

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  21. bully sticks and pig ears are sold dehydrated, not raw....

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  22. Just because something has been dehydrated does not mean that it has been cooked.

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  24. Food dehydrators work by removing moisture from food by heating them at 140 degrees Farenheit. That is certainly not raw. -M.A

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  25. To M.A.

    I agree. It is not raw. But 140F is also not enough to ensure destruction of pathogens. For example, when preparing jerky, USDA recommends cooking the meat first to a temperature of 160F before dehydrating at 140F. Here's the link to the USDA recommendations.
    http://www.fsis.usda.gov/Fact_Sheets/Jerky_and_Food_Safety/index.asp

    These recommendations are based on research studies reported in Journal of Food Protection, among other publications. Two articles on this topic are:
    http://www.ncbi.nlm.nih.gov/pubmed/15508655?ordinalpos=7&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_RVDocSum
    http://www.ncbi.nlm.nih.gov/pubmed/11510659?ordinalpos=1&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_DiscoveryPanel.Pubmed_Discovery_RA

    I am a subscriber to this journal and can provide you with a pdf file of the full text articles if you send me an email.

    My email address is phyllisentis@gmail.com

    Thank you for your post.

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  26. As a courtesy to all readers, I request that everyone identify himself or herself at least with some random initials so that a train of thought can be maintained. I have not blocked Anonymous posting, but I have enabled my moderation option and will block any individual posts that do not contain at least a minimal level of identification.

    Phyllis Entis, MSc., SM(NRM)

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