Humans have intelligence and are able to reason like no other animal. We do not rely on insticts any more and have no real need to harm other animal. With that it is cruel to eat meat and grow live stock just to slaughter and eat them. We can get all of our nutrients by other means and have no use in meat.
I definitely think that there are some ethical problems to eating meat. While I do not see a problem with it, some people do. I think that a lot of the arguments against having meat in a diet is that it is no longer necessary to eat meat for protein since a lot of foods have it.
From a modern ethical point of view, yes, eating meat would be a problem, because animals are living beings with feelings and the ability to experience pain.
From a biological/evolutional point of view, eating meat is perfectly normal, every animal does it. And what else are humans than animals with aspirations?
So to solve this conflict, we have to look at what is different between our meat "production" and animals eating other animals:
First of all, we do not use everything of an animal. We pick out the most tasty parts and throw away the rest.
Secondly, we often keep animals massively caged to maximize production efficiency.
Thirdly, we produce way too much meat and throw away a lot of stuff simply because no one eats it before it becomes inedible.
So what can we do to eat meat with a clear conscience?
Eat animals that live happy lives in the wild or on large meadows.
Eat meat especially from larger animals, since it's more meat per life taken.
Use as much of the animal as possible. If you have dogs, this is easy.
The easiest method would be to buy a whole deer from a hunter, take out all the meat and preserve it, give the rest to your dogs and have only very little to throw away.
People promoting vegetarianism or veganism for ethical reasons should start blaming predatory animals too, if they want to be consistent in what they do.
It is natural though, mankind would not have evolved this far if we never ate meat. The protein in meat is very good for our brains. While I would not recommend eating your own dog. We can raise certain animals and treat them humanly to feed us are required meat.
A balanced diet is very important, and that means both meat and plants. There are humane ways to raise and kill animals for eating. In general it is absolutely fine. The human body is designed to digest it and runs better with meat than it does on just fruit and vegetables.
The world is set up in a way where we take what we need from our surroundings. Animals just so happen to be part of those surroundings. Meat taste amazing and is a very good source of calories when needed. Animals kill for food and humans are just glorified animals.