Hair Pore Infection
In this condition pimple-like bumps or blackheads are found along the back, the sides of the body, and the stifles. It is more common in shorthaired dogs and affects dogs of all ages. Some causes may be due to grooming too vigorously, causing injury to the skin.
Once established, the infection bores down into the hair pores and causes a deep-seated disease in which draining sinus tracts appear and the hair is lost in small patches.
A condition called "Schnauzer bumps" is common in Miniature Schnauzers. Dogs suffering from this condition have many large blackheads running down the middle of their backs. Mild cases are treated in the same way as acne. Treatment is sometimes prolonged, requiring the addition of oral antibiotics. Pustules or small abscesses should be left alone. If you squeeze them you might cause the infection to spread downward into the tissues.