Q. I have 6 cats, my 2 black, male, cats have small eruptions on the furry bridge area above & to the side of the nose. They dry and form crust scabs.
DR. CHRISTIE LONG, D.V.M., C.V.A.
A. I do agree with the answer below that any time more than one animal in a household is affected with a skin condition we have to rule out contagious disease - even if not every animal in the house in infected. The changes you are describing to your cats' noses definitely sound compatible with infectious diseases like ringworm and mites (mange). However, if your cats stay indoors and don't have contact with cats outside of your other cats, and if none of your cats (not just the infected ones) came from a shelter recently it's probably not something contagious.
I will add that I have seen non-affected cats that carry ringworm and pass it to other animals in the household, so if you have any new cats check for ringworm.
Once infectious causes have been ruled out you can think about strange things, like immune-mediated skin disease (lupus) and solar dermatitis. Diagnosing what exactly is causing the problem and how to treat it may require taking a biopsy from one or preferably both cats.
A. Please have your cats seen by a veterinarian. Their condition sounds highly contagious - as it is apparent in numerous animals. They may have mange, which requires medical intervention.