Dog situation between tenants

[Irving Rivera]

Here for some advise: 

I'm a landlord of a multi-unit property in Chicago. Last week, one of the tenants' dogs bit another tenant at the entrance of the property, as they share the entrance space and their doors are next to each other. The injured tenant was taken to the hospital, and based on the footage from my security camera, which I have because I live in the same building, there was no provocation for the attack. Animal control was called, and I decided to issue a 10-day notice for the tenant to remove the dog.

The tenant with the dog is now upset because they want to make things right with the injured tenant, who is refusing to have any contact with them. Due to this, the tenant with the dog wants to break the lease because they do not want to get rid of the dog. They still have 7 days to comply with the notice I gave them.

What to do as a landlord in this situation?

TIA