Is it animal cruelty to feed a dog vegetarian diet?

I'm not sure where I got this screenshot from, but the post is only talking about animal cruelty to the dog, whereas feeding meat of other animals to a dog is cruel to those animals that are butchered.

So if someone said you have to feed meat to a dog otherwise this is cruel to animals, they are completely ignoring the animals being killed to feed the dog.
And no it is not cruel to dogs to only feed them vegetarian or vegan food. They can easily adapt to having no meat and can live the same length of healthy lives, and probably even longer.

What do you think?