Doggie germs
January 24, 2017 1:43 AM   Subscribe

Humans are innately repelled by things like rotten food and bodily fluids - partly because of social taboo, but also as a way of stopping us eating/handling things likely to make us very sick. Why aren't dogs repelled by 'harmful' things in the same way?
posted by mippy to Pets & Animals (14 answers total)
Dogs and the wolves they descend from are natural scavengers; in the wild, they will eat whatever is available at any opportunity, except plants. Most of what is poisonous to a dog is plant-based and human-made, like raisins and chocolate. A dog won't eat cocoa seeds in the wild but will of course eat your chocolate brownie.
posted by DarlingBri at 1:58 AM on January 24, 2017 [5 favorites]

I believe one reason dogs can handle carrion and such is just that the digestive tract is so much shorter - there's a much shorter time for microbes/bacteria (whatever - I'm no expert) to multiply to harmful levels.
posted by quinndexter at 3:14 AM on January 24, 2017 [3 favorites]

A big part of this comes down to differences in how dogs and humans learn. Because we can write and speak, we can pass down lessons about foods to avoid to future generations. Dogs don't do those things, though, so they can't benefit from previous generations' experiences unless they're living in a group with multiple generations present. I know not to eat certain mushrooms not because I've eaten them and gotten sick, but because my parents told me not to eat them.

Additionally, dogs have very different memories than we do. If I eat a piece of rotten food and get sick hours later, it will be pretty easy for me to make the connection and realize that the rotten food made me sick - especially if this happens more than once. However, dogs aren't retrospective, so by the time one is getting sick, he or she has long since forgotten the piece of rotten food they ate earlier.

Also dogs are not descended from wolves. Dogs and wolves share a common ancestor.
posted by schroedingersgirl at 4:14 AM on January 24, 2017

Also dogs are not descended from wolves. Dogs and wolves share a common ancestor.

Absolutely. My apologies for being lazy with my language.
posted by DarlingBri at 4:17 AM on January 24, 2017 [1 favorite]

"Rotten" meat and bodily fluids aren't typically harmful to dogs. They have a much shorter and more acidic digestive system than we do.
posted by fshgrl at 5:29 AM on January 24, 2017 [2 favorites]

Domestic dogs have been bred for a few thousand generations to be trainable -- that is, completely obsessed with getting as much food as possible. Wild animals and some specific dog breeds are much more picky about their food.
posted by miyabo at 5:57 AM on January 24, 2017 [4 favorites]

Also better noses help them sort out the good from the bad. (And DarlingBri had it right the first time...dogs are most definitely decended from wolves (humans and apes share a common ancestor, millions of years ago, dogs are much much more 10-20k years), and share nearly identical mitochondrial DNA, meaning probably just one common female ancestor, likely a pregnant grey wolf somehow separated from her pack...despite however many people the scientist interviewed in that Atlantic article got drunk. If the dog DNA shows recombination with wolf DNA (which could probably also come just from interbreeding between dogs) it would have to be exclusively male wolves interbreeding with female dogs to preserve the mitochondrial DNA. I'm surprised they didn't mention mitochondrial DNA at all...smells like bad science. /derail, sorry)
posted by sexyrobot at 7:58 AM on January 24, 2017 [3 favorites]

Thanks for the answers so far. So is it less likely with dogs that eating excrement, urine or vomit will make them sick? I believe human urine is sterile, so drinking your own won't make you sick, but drinking someone else's is likely not to end well. My understanding was that the visceral reaction humans feel to things that are 'disgusting' is mostly to keep us away from them?
posted by mippy at 10:02 AM on January 24, 2017

The problem is really - okay, so I have a large breed dog, roughly the size of a wolf. He can really eat a lot of things and be fine. At worst he will throw up. I cannot tell you how many times I've been on a late night call to a vet only for them to say "No, actually him eating half of your medication is not actually toxic to him."

But I also have a friend who's a vet, and he says that a lot of the stuff my dog merrily chomps down on if unprotected will actually kill smaller dogs.

So I think it's likely that with dogs of the original size, eating those things may not make them as sick - but breeds we've messed with more may well.
posted by corb at 11:19 AM on January 24, 2017 [1 favorite]

Human urine is not sterile.
posted by agregoli at 12:16 PM on January 24, 2017

The sterility of urine came into question about 3 years ago. Prior to that, it was believed to be sterile.
posted by talex at 12:21 PM on January 24, 2017 [1 favorite]

I don't know but as the mother of children, humans are not always innately disgusted by consuming all kinds of things - including dog poop, own poop, own pee, crayons, styrofoam, rocks, and shampoo, to name some of the things my friends and I have had to call poison control or my doctor about. Humans also fight their way through consuming things that are disgusting at first try like smoking or in my case, beer, that may kill them.

It seems like of what you seem to be assuming is innate is learned behaviour.
posted by warriorqueen at 12:54 PM on January 24, 2017 [6 favorites]

Dogs will eat their own poo if they are nutritionally deprived enough - that's why it's a symptom of parasites. They'll go back for that second round and leach out the remaining nutrients because they're SO HUNGRY. It must be something evolutionary for a species that has no control over food production and is subject to diseases in the wild. Like some kind of fail safe for staying alive. It's actually kind of awesome! It is actually bad for them though, it's a sign they need treatment.
posted by benadryl at 1:30 PM on January 24, 2017 [1 favorite]

Dogs have a higher internal body temperature and acidic level in their stomach which make eating carrion not a big deal. Their bodies take care of it. There isn't a selective pressure to make eating it disadvantageous.

In regards to the "dogs are not wolves," that is false. Dogs and wolves are the same species. If you take, for example, a Golden Retriever and a Gray Wolf and mate them; they will produce fertile offspring. Yes, they do share a common ancestor -- because they are the same species.
posted by jms18 at 10:07 PM on January 26, 2017

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