The woman was riding the horse just past trail two when the incident occurred after 6 p.m.
West Barnstable Fire crews arrived on scene with an off road vehicle to stabilize the woman.
She was taken to the parking lot at the beach to meet a Medflight helicopter to an area trauma center.
According to Lt. Troy Jewett, there is no update on the woman’s condition.
Barnstable Fire crews also reponded to the call by boat but were not needed as West Barnstable crews were already on scene.
Sandy Neck beach staff also assisted.