Cat spraying, need advise

[Joe Provateare]

Tenant tried to have a cat without putting on the lease. I confronted the tenant and we decided she'd pay the cat deposit and monthly pet fee. Cat is now spraying as it wasn't fixed. They have since taken cat in to be fixed, but feel damage is already done and smell is bad. Am I stuck in this scenario until lease is up, since I allowed tenant to keep cat even though she originally broke the lease agreement? Will be visiting with my attorney on options, but curious if others have ran into this scenario. This is within my apartment complex in IL and is impacting tenant below.