My horse use to get them really bad. I mean half way up the leg bad on both hind legs. I tried everything. Ointments, home remedies and numerous vet calls. All I can tell you is what worked for me.
You do need to get the thick scabs off because they are more callus then just a scab that forms on a cut and new skin/hair cannot grow under them. HOWEVER!!!! Do not just pick them off!!! First, wash the infected area. I use a medicated shampoo, but Dawn dish soap is suppose to be antibacterial too. Using a sponge, I gently scrub the area, then hose it off. Some of the scabs will come off with the sponge and I will also pick off the loose scabs. Anything that does not remove easily, I leave alone. Sometimes none come off, just stick with the program. I then dry the legs with a towel and let air dry. Once completely dry, I put triple antibacterial ointment on all of the infected area. I get a decent size tube for $1.00 at our local Dollar General. Repeat daily or every other day until gone.
I keep a close eye on my boy and the minute I see any scratches forming, I start to work on it immediately and it really nips it in the bud.