Oh, yeah. That was the other part. Benzoyl peroxide bath, mitaban dip. Andy had it everywhere but worst on his face and feet. The benzoyl peroxide is horrible, dries out the hands something awful.... and the lincocin tore up his stomach unless I gave him yogurt every day.
But we survived.
Immune support. There are so many things that can be done, including astragulus, vitamin c, bovine colostrum, mushroom extract.... that is just a few of the ones that I can remember off the top of my head. As far as probiotics, I've used several and recently found one that goes in the drinking water that seems quite helpful to the cats, but it's for dogs as well. I only got the sample bottle but am going to go ahead and order the 8 oz to give it a proper try. The idea is to improve mouth health, but the litter box seemed less stinky in the am when all the cats were on it. I tried it on me first, of course, and it worked well.
http://www.piphealthyproducts.com/Pet_Water_Additive_8_oz_p/pip36080h-8z.htm They have it on amazon as well, but it doesn't seem to be on prime, sadly.
You can research immune support for dogs and decide which you'd like to implement, or you could consider a consult with a holistic vet and come up with a specific plan (and dosages) that way. Homeopathics can also be really useful, and a good holistic vet will be able to identify what would be needed. Acupuncture could also be used to balance the system out and thus improve immune response.