FRUIT COVE, Fla. -- A 2-year-old boy bitten by a dog inside a St. Johns County home on Friday morning will need surgery but should make a complete recovery, officials said.

Officials said the child visiting a home of a relative in the 900 block of Fruit Cove Road was bitten on the face by a 100-pound bullmastiff dog.

"A toddler was placing his head on the stomach of a sleeping mastiff, and when the child did so the dog swung around and bit the child on the face," said Paul Studivant with St. Johns County Animal Control.

The boy was transported to Wolfson Children's Hospital. His name and condition were not released, but Studivant said the toddler will need serious reconstructive surgery.

Animal Control took custody of the dog, named X.B., which officials were told had never shown aggressive behavior before.

"Any startled animal, regardless of how passive it is, if you startle it, the animal will react. This animal very well could have been startled," Studivant told Channel 4's Laura Mazzeo.