Horses are just big doggies.

well, the horse is a non ruminant herbivore that has an entirely different digestive system than a dog. The horse also lacks the ability to vomit, which is why they colic all the time. Lets see, the horse also essentially is walking around on one toe, while the dog course has 5. Should I go on?

Try to get a horse to fetch a stick....

here is a horse with a dog mouth...

Entirely different families