Schnauzer skin problem

Question
QUESTION: I have a mini schnauzer we adopted from a rescue, he is about 18 months old.  For the past two months he has had developed a series of crusty bumps that started on and around his back near  his tail. They did not appear to itch him but he did not like them to be touched   Our vet treated him with a 10 course of cephalexin it had no effect.  We used a medicated shampoo again with no positive results. The bumps have now shown up on the ends of his ears and the tip of his (docked)tail.  The scabs on his tail are causing him a great amount of discomfort. We did another 10 run of the cephalexin with no change.  The bumps on his ears and tail are irregular, very crusty (as if they are weeping), they are very hard and of mixed coloration, the bumps on his back are the same just not as tall.  Any ideas on what they may be and where to go from here?  Thank you

ANSWER: I think your vet proved that this is not a bacterial skin infection.  It could be many other conditions including sarcoptic mites, Schauzer Comedo Syndrome, allergic reaction to anything including fleas, molds, foods, etc. , or even a fungal infection.  You might ask for a referral to a dermatology specialist or call around and find someone that does lots of skin work and get a second opinion.

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QUESTION: Thank you, we are trying to eliminate a few of these other possibilities now.  We have him on Prednisone for the allergic reaction and Cefpodoxime for another shot at any possible bacterial infection.  But so far after two days of prednisone there is no improvement in his condition.  Next we are going to treat him with Revolution for the possibility of sarcoptic mites, but honestly his bumps do not look like any of the pics online for mites.  Thank you again for uyour help.

Answer
Revolution will take a long time to kill any sarcoptic mites.  I would recommend having him dipped in an insecticide solution containing either amitraz or phosmet to rule out sarcoptic mites.

Being a young dog, he may have an underlying food sensitivity.  You might ask your vet about that as a possibility.  A dietary trial with a new type of protein that he has never before eaten (like deer meat or salmon), or or a hydrolyzed protein (Hill's z/d diet) for 6-8 weeks may give you a clue.