Legally speaking, Can a landlord............

I think it depends on the lease you signed, if it is stated that you can have or not have and animal, I don't think he could just walk over and say what he feels in that moment.

if he paied some type of fee to keep his pets yes....did u like sneek ur dog in there with out permission and not pay a pet fee?

What does it say in yor lease? Did you pay a pet deposit? If you didnt mayybe you can offer him one to keep your pet. But yes he can if no mention of ok to have pet in lease.

If the lease, local ordinances, or apartment complex policy says something about restrictions on certain breeds of dogs and your dog is that breed, then yes they can. Also, some places have restrictions on size, though if the neighbor's dogs are bigger than yours that wouldn't apply.

As far as the barking and stuff though, you could try lodging complaints as far as noise violations go.

The lease does state that we can have a dog, within the weight limits (which he is.) Although we weren't required to pay a deposit or pet rent for him. Apparently there's a leak in the apartment below mine and the landlord seems to think that it's caused by my dog. Although, they have come to my apt and looked and it's the hot water radiator leaking, and not the dog. (I'm not real sure how a dog can create enough liquid to cause a leak though. He's barely 20lbs.)

The landlord was fully aware that we had a dog when we signed the lease. We informed him of the dog, knowing most places don't allow dogs in this area. He had no issue with him a year ago when the lease was signed.

he can't just change his mind.He'd have to draft a new lease for you to sign.

That's what I thought. And it would have to be the same for ALL the tenants, right?

If the terms of your lease state the policy is no dogs, your landlord can make you get rid of a dog...

If you think the tenant downstairs should also have to get rid of his dogs because the policy is no dogs, bring it to the landlord's attention.