A cordless gas dehorner with a pistol grip. The trigger lights it and shuts it off, and a gas cartridge gives at least two hours of work. The tip reverses between 17 mm and 19 mm to suit the calf.
It heats up in under 3 minutes, to a maximum of about 700 °C. Use it with the gas cartridges it is made for, in a well-ventilated place, and keep it away from walls and anything that burns.
Ask your vet about age limits and pain relief before dehorning.
