I have used alongside veterinary treatment. It doesn't harm. Did it help, well my horse came sound, would she anyway, probably.
Interestingly my insurance covers me for alternative treatments, my vet doesn't believe in it though.
I have lent magnetic wraps to a friend who has noticed signs of improvement.
If it's a new injury, you need to make sure your wraps are not overheating the area. You meet be above or below the injury, not over it directly.
My old boy has worn one for years. It's £30 he has it on all the time. I know mine helps my arthritis so why not ease his.
It's not a miracle but easies the pain.