The horse's legs swell

Doberman, bulky? Maybe the same way? A pushtisch is a belt on which the stirrup is held
Bandage tight on the swelling is by no means possible, you can only put quilted jackets after work (most often with iodine compress, sometimes with a cooling or warming gel)
The causes of edema can be very different - injuries (bruises, strains) Excessive or abrupt data of the load, hard ground, opiates, slimyards, etc.
If the swelling is not only on the legs, but also on the sternum - problems with the heart are possible.
In any case, contact a vet or a vetka.
And for prevention - and really you can smear cooling gel after work, without quilted jackets

from injury to infection.

Fresh filling - to cool. Next is a double action gel.

Threat worst ligament rupture or infection in the bag.