As the comments pointed out, horns aren't very ideal as a cooling device for a fair few reasons.
Horns are nowhere near as efficient at cooling a creature as opposed to ears for example. As ears have a constant flow of blood, the blood can carry the heat directly to the thin outer edge with the biggest surface area and airflow, where it quickly gets dissipated. Horns don't have a constant blood flow in them, unless you have the velvet-covered horns deer have, which can get caught in branches and tear easily. Besides, bone is thick, so it has less surface area and airflow, so retains more heat naturally. You would need a tree like structured horn, with thick base to carry the heat, into smaller branches with more airflow and surface area. The outcrops would need to be thin, and hence won't be very strong. If you would need them to be strong, you would need a lot of surface area still, making the horns unnecessarily big and unwieldy.
All in all, the horns would be big, velvet covered, and tree-like. A lot of disadvantages for something like a cat-like predator, and don't make sense from an evolutionary standpoint as there are a plethora of better options available.