Five fire departments from Drayton, Linwood, Moorefield, Milverton and Sebringville responded to the scene on Wellington Road 86 just before 12:30 this morning.
The barn contained some horses, dogs and puppies and was fully engulphed when they arrived.
The road remained closed for fire operations but has now re-opened.
No injuries were reported however 3 horses, 2 dogs and 11 puppies are reported to have been lost in the blaze.
The damage is estimated at $500,000.