I have 11 horses, 5 trained ridding horses. I unfortunately can't afford right now to buy them each their own set of brushes. So they share. I never had a problem untill recently one of my mares developed a fungal infection on her back. A few weeks ago four of the trained horses went out working cattle, they came back and brushed Trapnet (horse with fungal infection) and my pinto mare with the same brush. Week later Rainbow had a bald patch on her flank, thought it was a bite mark, doctored it, went away. About a week later she had some balding patches on her neck, that's when I knew... For Rainbow thankfully it only took a few applications of wound oil, she's in good coat condition, unlike the other mare who is not a good doer and has trouble keeping weight on. Now if Trapnet worked all brushes gets disinfected before they get used on another horse. I just have a can of general purpose disinfectant I bought from the local co-op, throw a bit into a bucket of water and all brushes gets a vigorous swril thru that bucket before being used on the next horse. No further problems.