If you have a Schnauzer, it's likely you are familiar with the term Schnauzer bumps. Schnauzer bumps are similar to blackheads and are found all along the Schnauzer's back and rump. They are somewhat raised, and they are itchy and can have red pustules along with the blackheads.
Schnauzer bumps is a common problem among Schnauzers, partly due to genetics and partly because this breed is meant to be hand stripped and not clipped. When you clip a dog and you don't card out the excess hair, the hair follicles clog with oil and excessive undercoat hair, and the follicles become infected. Stripping out undercoat or hand stripping the coat can stop this problem.
Benzoyl peroxide shampoo is helpful to use on this condition. It helps flush out the hair follicles and dry up the oil. When you use a medicated shampoo, be sure to let it sit on the skin for the recommended amount of time before rinsing. Then be sure to card out the hair after trimming it to help alleviate this problem in the future.