Highmore sustained an upper-body injury during Saturday's preseason contest against Montreal and won't return.
Highmore was limited to 1:39 of ice time due to the injury. During the 2023-24 regular season, he recorded nine goals and 31 points in 43 contests with AHL Belleville and had two assists in seven NHL outings with Ottawa. Highmore has been competing for a bottom-six role during training camp.