I’ve heard that horses are actually omnivores instead of herbivores, or at least there is/was some debate about it. Is there any semblance of truth to that or are people just being assholes and spreading ridiculous “facts”? Also I was not aware that horses had horizontal pupils like goats.

drferox:

Well, most of the ‘horses are omnivores’ argument comes from a guy that wanted to sell his book about ‘deadly horses’ around 2012, as if having a taste for flesh is required to make these creatures deadly.

But no, a horse is still a herbivore even if it eats the occasional meat, just like a cat is still a carnivore even if it eats a potato chip.

Many stories of horses being fed meat or fish (like Iceland, Tibet) involve feeding relatively soft meat products to horses in otherwise austere conditions, eg not much grass. Horses are a monogastric animal, they absolutely are capable of deriving nutrition from meat that they eat. However, their enormous gastrointestinal tract requires a minimum amount of plant fiber to not do something catastrophic and fatal. Seriously, colic is bad news.

A horse is a highly adapted herbivore and it’s quite capable of happily living its life on a 100% plant diet. Most of the meat eating horse stories seem to be extreme conditions where the horse will eat something to not be hungry, or humans have deliberately exaggerated an otherwise natural survival behavior.

If you give the horse free choice and plenty of food, I’d not expect it to go for the hamburger terribly often over lucerne and molasses. If it’s ‘eat meat or starve’ then yeah, just about everything will give meat a go.

Horses are a lot of things, but I’m not about to stop calling them herbivores.

You know those fish that stick onto the sides of aquariums, plecos? Those guys eat nothing but algae and the bio-film (bacteria) that grows on various hard surfaces, as well as occasional soft plants. You can keep one in an aquarium and it will live its whole life happily eating nothing but plants and bacteria. 

They will, however, chew on dead fish if they get the chance. Not just if they’re starved,they’ll chew on fish for no other reason than because it’s there and has a lot of energy in it.

Meat has plenty of energy in it. Even herbivores can benefit from a bit of protein sometimes. Doesn’t make them not herbivores. 

Also worth mentioning: giraffes and some other ungulates will chew on bones, probably to get minerals. I’m not certain if this counts as eating meat or not, we’re talking about very dry, bleached bones. It happens, though, and pretty regularly.