Tenant complaining about other tenant's dogs barking

[Polo Vazquez]

I bought a duplex with one tenant on it and she has two dogs. From her contract I can tell she paid pet fee to have the dogs. I recently moved in another tenant and she keeps complaining about the dogs barking next door when she enters her apartment. The tenant with the dogs swears her dogs don't bark that much. Tenant number two is threatening to leave if I don't tell the other tenant to get rid of the dogs. Should I hold her accountable for her lease even if she leaves or should I let the tenant with the dogs lease expire and take the property? this are townhome style duplexes so I can't control all the neighbor's dogs. If the neighbor on the other side had a dog barking there would be nothing I could do. please share what you would do