Police officers received a report of the collision, which occurred on the Antrim Road in Newtownabbey shortly before 1.45pm on Saturday, January 14.
Commenting on January 16, a PSNI spokesperson said: “It was reported that a horse, with a male on the cart, lost control, causing damage to two vehicles, with one woman reporting minor injuries.
"One boy, aged 16, was cautioned for failure to stop and remain at the scene of a road traffic collision and being in charge of a horse drawn vehicle without due care and attention/without reasonable consideration."
Providing an update today (Friday), Chief Inspector David Gray said: “Our investigation remains ongoing.
“We are pursuing a number of lines of enquiry at this stage and we would reiterate our appeal for anyone with information, mobile or dash-cam footage to make contact with police.
“Sadly, the horse involved in this road traffic collision had to be euthanized by a vet due to the extent of its injuries and a number of vehicles were also damaged. Thankfully there were no serious injuries reported.
“Anyone with any information that could assist with our investigation is asked to contact police on 101, quoting reference number 810 of 14/01/23.”
A spokesperson for Antrim and Newtownabbey Council added: “Council is liaising with the PSNI in relation to an incident involving a horse in the Antrim Road area of Glengormley on January 14.”