Man's Best Friend is a Side Quest in Velen.

Travel northeast of the Inn at the Crossroads and eventually you will come across a cottage. Upon arriving you will see a wild dog outside trying to get into the house. Kill the wild dog and listen to the whispers coming inside.

You will soon find out that a couple of kids are living there alone and they're hungry. You can choose to give them food or 25 in coin. They will give you a small prize in return and the quest will end.