Tenants with Dog Became Service Dog Issue

[Chan K.]

Hello Everyone, 

I have a situation where tenants moved in without a dog. 

In the ads and when they signed the month-month lease (also in the lease paperwork), I told them that no dog is allowed in the building. 

Lately, they have been bringing a very big dog around, and we have been given them timeline to get ride of the dog. This morning I got a surprise text stating that "my wife is really sick, and she needs a service dog ... we will get you proper paperwork for the dog from the doctor". They just moved in about 2-3 months ago ... I feel like that they are slipping this in. They also live in the second floor with a very big dog (one of my long term tenants complaint about it) .... any suggestion on how to get around this [I don't want to have dog and don't want to loss my nice long term tenant]? I was thinking about issuing the people with dog 30 days notice to quit.... any thought ??