A. Typically nipples can have small raised black things encircling the nipple called comedones. These are blocked hair follicles that become clogged with keratin (skin debris). Typically if this is mild it can be controlled with cleansing the area with benzoyl peroxide or salicyclic acid (i.e. Stridex Pads are a good OTC source for this).
IF the skin appears infected (draining yellow discharge or painful/itchy) then I would consult with your vet to get antibiotic treatment as well. And as always when in doubt if this is truly a comedone or not, have a vet take a look to confirm.
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