Part of the problem of being an apex predator like a lion or cheetah, is that any broken bone is a death sentence. A water buck with a broken bone can still eat grass while it heals. A cheetah with a broken bone is going to starve before it heals. So cheetahs are very very careful about situations where they might get hurt.
A cheetah lives by running down it's prey. Even a small injury that slows it down like a sprained foot, means it doesn't eat until it can get up to speed again.
The cheetah decide it wasn't worth the risk to continue to pursue that animal.
Maybe because the cheetah wants to run away from the water buck.
I think the cheetah is scared of water bucks whether or not they have horns.
Because it doesn't want to get trampled. An animal doesn't need horns to trample or fling and animal to its death. Water bucks are large animals, cheetah's stick to Thompson's gazelle and similarly sized animals, though males though can often take down wildebeests, especially if there is more than one of them, the majority to not go for larger prey like that or even the larger antelope unless desperate(and sometimes they pay for that mistake wasting energy trying to take down something they just can't).
A cheetah going after a water buck is extremely rare because of their size, and also because they have foul, musky, oily meat. Was likely a desperate ploy, especially to waste so much time and effort on it. NO lone predator like that will stand in the way of a charging, much larger animal. Would you not run? lol It happens!
And if it had no horns, it was a she. Even the females are heavy and can give a fatal kick, cheetah's do not get in the way of those kicks if they have a choice.
*ADD* I did NOT say they cannot, I said they often don't. lol I've seen males do it, I've seen larger bachelor groups take down even zebra. Females though, they normally can't take down anything much larger than themselves and often don't try unless desperate. This doesn't mean they don't try sometimes anyways, and it also doesn't mean they don't succeed, it's just rare!
The answer to your question is this: The water buck could have killed the cheetah simply by trampling it and beating it down with its sharp hooves. Very few animals are stupid enough to stand in the line of fire unless they're like the ever arrogant leopard who can and often does stand in the way for a quick throat snag in the....most interesting circumstances(unlike most predators, excluding lions who may also do this, I've seen leopards jump in front of stampeding wildebeest and catch one). Of course, cheetah's are the smaller and less powerful of the African cats, next to ones like the Serval and such of course, but of the cats around their size, they have the least power and are built for speed, not battle.
I saw a female cheetah and her cubs(almost her size, two or three I can't remember if it was the two brothers, or the one who had two boys and one girl, was featured on Big Cat Diary) try to take down a wildebeest, they fought with it for something like 20 minutes before discovering they not only couldn't hold it down, but mom was unable to properly get her mouth around it to suffocate it since she was too small.
just because it didn't have horns doesn't mean that it couldn't hurt or kill the cheetah. it could have easily trampled it especially if the cheetah was already worn out from chasing it
I was watching a cheetah documentary, a cheetah tried to take down a water buck five times it's size but couldn't. The water buck ran into water about knee deep and there was a stand off, because the cheetah didn't want to go into the water.
The water buck charged the cheetah a few times, the last time being the most aggressive and the cheetah took off for good.
How could the buck have hurt the cheetah if he or she didn't have horns?
