Neighbor is complaining about my Tenant's Dog Barking

[Chris MacCary]

My tenant has a dog that they keep in a large pen in the large side lot to our rental property. The neighbors in the house that borders the side lot are complaining that their dog "barks all night and causes our dogs to bark as well."  Since my tenants moved in a few months ago, they have had several issues with the neighbor (all the neighbor's fault) over dog issues.  The complaints did not start until my neighbor had an argument with the tenants over said dog issues. None of the other neighbors have complained and the other neighbors I am still in contact with said they haven't noticed any excessive dog barking.

Current tenants pay the rent on time, maintain the property, and have not received any complaints from others around them. This feels like a neighbor issue moreso than a tenant issue. How would you handle this? Ask my tenants if they can keep an eye on the dog barking and leave it at that?