Depends on which engine and gearbox have been fitted. The figures below come from the link further down . If the horse float does not have brakes then the weight of the float + horse is likely to exceed the 750 kg limit.
TOYOTA HILUX SR 4x2 - TOW CAPACITY
Towing capacity - trailer with brakes (kg) 2250
Towing capacity - trailer without brakes (kg) 750