Kicking out dog vs. Increased policy coverage

[Lauren Kelley]

My husband and I just bought a duplex and moved into one of the apartments two weeks ago in Middletown PA. There is a large dog that lives upstairs that was friendly when we met it originally in the tenant's apartment. Since buying we have learned that the dog is friendly inside, but aggressive if approached outside. Two days ago the dog bit my husband when he reached out to pet it. Our homeowners policy does not cover bites from aggressive breeds (she is an akita/pitbull mix). 

Do we kick the dog out, or require an umbrella policy paid for by the tenants? 

They are model tenants otherwise...