I live on a farm with multi rentals. I aske dhte landlord if I could get a puppy. I was told no because they think the living space is too small for a dog. Only to find out that the landlord had aloud one of the other tenants to get a dog. This dog is 3x bigger than the dog we wanted to get. The tenant and the landlord have been hidding the dog so we don't know that they have one. We were also offered not to pay rent for a month to make up for the fact that we can not have a puppy. Is there something I can do? Is the discrimination?

I would say it is discrimination on an ethical level; not much I think you can do about it though other than work something out or move and state that IS exactly why you are moving.

You need to look for a landlord who will accept a "puppy" and then give notice where you are and pay your rent... your landlord is LEGALLY discriminating and you will be evicted for non-payment of your rent.