The midfielder was hurt after just eight minutes of the game when he appeared to collide with a team-mate after stopping a run by Bristol City's Lee Tomlin.
A post on Huddersfield's official Twitter account read: "Break in play as Hogg receives treatment moments after he stopped Tomlin running at the Town goal."
After a lengthy delay, which led to 15 minutes of added time at the end of the first half, he was carried off the pitch on a stretcher.
A further Twitter post read: "Jonathan Hogg is replaced by @BillingPhilip; we wish him help and hope he has a speedy recovery."
A spokesman for Huddersfield confirmed Hogg had been taken to hospital with an injury to the head and neck region.