A woman attacked by what she described as “a large, red/brown dog that is just smaller than a Shetland pony,” was seriously injured, Gatesville police said in a Facebook post Wednesday.

Officers responded to a report of the attack last Friday in the 1600 block of Waco Street.

The woman’s injuries included a large laceration to her head that will require surgery to repair, police said.

Police believe the dog could be a Mastiff, Great Dane mix or similar large breed dog that weighs more than 100 pounds.

Gatesville Animal Control officers and police have been unable to locate the dog since the attack.

They are asking any who sees a dog matching the description to not approach or try to catch the canine, but call police immediately.