Look at the abandoned dogs makes more sense because it states that the dogs are ownerless. "Deserted" indicates more of an empty setting like "the town is deserted" meaning there is no one there.
So 1 is better than 2.
3 would work. It strongly suggests you rely on the dogs for physical or even moral guidance rather than simply having two dogs as pets.
1. Look at the abandoned dogs.
2. Look at the deserted dogs.
(Which one is a correct term? Can we use both expressions? Do you have some other terms?)
3. A dog is a companion animal. I have two companion dogs.
(Is this expression right?)
2 answers
Yes, 1 and 3 are fine.