We are probably all aware that there are a number of safe human foods that are poison for dogs and/or cats, but what about the opposite direction–are there known substances perfectly safe for dogs and/or cats to consume that are deadly poisons for humans?
Maybe rotten meats. Humans can get very ill from eating turned meat. Dogs on the other hand the nastier the better.
Dogs eat dog shit and cat shit (and other shit?) with some regularity. I think that would make a human very sick; kilt dead, I dunno.
The issue is dog and cats are carnivores. Carnivores are much more susceptible to toxins found in plants. Humans as omnivores can handle a much wider variety of plant toxins. Herbivores can eat all types of things that are very bad for humans.
A dog or cat can be sustained on an all meat diet, something humans can’t do. The high pH found in their stomach allows them to eat all types of bacterial laden food with very little risk. Their specialty is meat, there are plenty of meats they’d happily eat that humans wouldn’t consider, but I don’t know of any meat that humans can’t consume.
Not sure about deadly, but most of what my dogs choose to eat on their own would make humans sick (long-buried bones, cat shit, hedgehogs, CD cases, etc.)
Cats are obligate carnivores. Dogs, although they evolved from carnivores are actually omnivorous.
While I’ll concede that we can throw disagreeing cites back and forth all day, the more rigorously science backed cites will overwhelmingly be on the “dos are omnivores” side.
Our new dog, Tuxedo, has found that his favorite snack flavor is Deer Pellets!
I’ll have to check on line because the locl store doesn’t carry that flavor.
A lot of the things that dogs eat that would make humans sick, also make dogs sick. They just eat them anyway.
And not really something “ingested”, but humans specifically are a lot more vulnerable to brown recluse spider venom than most mammals.
My friend and I walk our dogs together every morning on trails in the woods where they’re off leash. All three of them spend the entire walk eating deer and rabbit poop. It must be good roughage!
Like all that I’ve ever had my dog thinks going for a walk is a trip to the poop buffet, where he gets to sample the shit of several different species of animals.
Never had it make any of my dogs sick.
Yet my current dog won’t eat the vomit flavored Jelly Belly. :rolleyes:
While dogs and cats more tolerant things that would make us ill, it’s primarily the fact that they generally don’t associate what they ate with feeling ill. Dogs may vomit and get the runs after eating something that made them ill and happily eat it again with the same results.
Trixie ate the head off a very large pack-rat yesterday. Dirty girl.
As the OP is specifically asking about cats and dogs, this is maybe a bit of a sidetrack; but I remember I’ve read (probably in some book by Matts Bergmark) that the anticoagulant dicoumarol was, for some reason, originally tested on rabbits (instead of the usual rats) to establish the toxicity index before being tested on humans for medical use. As much later turned out, rabbits have an exceptionally high tolerance for the drug; while rats have an exceptionally low (with humans somewhere in between). Had the first test been done on rats, the substance almost certainly would have been considered too dangerous to try on human subjects…
Penicillin kills guinea pigs, and we can all be grateful that early testing was not done on them.
Many animals, not just the dung beetle 
, eat excrement, their own or others’, to get the extra nutrients.
Back when I had two cats, one of them would eat the others’ vomit. :eek: At first, I shooed him away, and then decided that if he wanted this partially digested $40-a-bag cat food, he could have it. I mean, he’d hear his “sister” horking, and his kitty face would light up.
Our two current dogs do NOT eat poop – they’ve even turned up their noses at goose poop.
But Ginny eats socks and tried to eat a roofing shingle once.
I dunno about that, it seems humans can subsist on a all meat diet.
But yes, meat that is “off” can be consumed safely by dogs but often not by humans.
And of course extending beyond cats and dogs:
Birds don’t detect capsaicin (the stuff that makes hot peppers hot). Mammals, on the other hand… so some bird feed has it added to keep the squirrels from chowing down.
Cattle can eat grass. I don’t think grass is poisonous to humans, per se - but we can’t really digest it. An ecological argument for using grazing animals is that they can take unusable acreage and turn it into food for humans.
I don’t think anyone has yet to come up with an example of something that’s truly poisonous. I mean, poop might make you sick due to the bacteria it contains, but that’s not the same as “poison”.
I don’t know if cattle can safely eat plants that are toxic to us - but I wouldn’t rule it out. That would be a good example of something that meets the OP’s criteria.
Perhaps part of the issue is that if there was such a thing, unless a cat or dog needed it, it would not be marketed due to fears that a person, especially a child, would ingest it, and lawsuit fear. I’ve heard that all pet food is made to human consumption standards.