Okay, you need to be very careful when you were talking about dogs and whether or not you like them. If you are talking about living dogs, you absolutely MUST say the plural form – dogs. I like dogs. The reason is that if you say, I like dog, everybody will think that you mean that you like eating dogs.
If you want to talk about just one living dog, you can say – I like this dog, or, I like the dog. That's no problem. But you absolutely cannot say – I like dog. Unless, of course, you really do like eating dog.