Most landlords either allow pets or they don’t with no middle ground. If you’re a landlord that really doesn’t want pets on your premises then you’ve got to hold a firm ground because you can lose your legal rights if you tolerate a tenant having a pet for a significant period of time.
Your first step is making sure your lease clearly states that pets will not be allowed or you can specify that you will accept certain pets, like fish, and that others will not be tolerated. If you’re very strict about this rule you can even ask your tenants to sign or initial this part of the lease.
Then, when you become aware of a pet violation you must act immediately and inform the tenant in writing that you’re aware that there is a pet on the premises and that this will not be tolerated. You may want to give them a warning or notice initially or you can dive right in to a Cure or Quit notice which basically lets the tenant know that if the pet isn’t removed you will begin eviction proceedings.
If it does come down to an eviction situation make sure you have written documentation that the tenant was informed about your policy, the date you realized there was a violation, your efforts to notify the tenant of the problem and the Cure or Quit notice.