I'd be guessing but maybe 1950's?
So what did they use them for? What are the modern equivalents? Are you even allowed to do the same thing to the animal these days? Thanks.
Fekin OuchFiring is (was) a practice of repairing injuries.
Say a horse damages a tendon on the back of its leg (very common injury) you would take that flat tool (top one in the op's photo) heat it in the forge, and run it round the back of the horses leg a few times.
The idea being that the burning would encourage blood flow to the area and the scar tissue would make a stronger repair.
Commonly done in race horses to get them back into work quicker.
That's bar firing that leaves a set of stripes on the back of the horses legs.
The middle tool is for pin firing, same idea just done in multiple spots.
The top tool is a tail iron.
If you find an old picture of a race horse often they have very short tail with a square end. You cut the tapered tip off the boney bit of the tail and then put the hot iron on it to stop the hair growing back tapered.
Tendon firing is not a reccomend practice under uk veterinary rules but I'm not sure if it's actually banned.
Tail manipulation for cosmetic reasons has been banned.
I still see plenty of "fired" horses about, normally ex-racers that have come from Ireland. It's done with cryogenics now, much the same as a freeze brand marking.
No real supporting evidence of it being effective.
Vetinary preference currently in the uk is shockwave or ultrasound therapy with some offshoots of cold laser, magnawave and so on. Shockwave has some decent research results. The others are not so well proven but none are invasive/painful/distressing for the horse so nothing to loose trying them really.
Fekin Ouch
(anastasia to numb the leg)