Many Blues, R&B, etc. list horns as an instrument, i.e. the Memphis Horns. It can be a substitute for saxophones, trumpets, etc., but without knowing which instrument they are actually playing it is difficult to list on recordings. I see "horn" used for this a lot, however, that is actually for things like English Horn/French Horn, not really supposed to be for woodwind instruments like saxophone, which is sometimes listed as horns.