LDennis,
Coat the horn caps with a liberal amount of WD-40....it will make then shiny until it drys fully. You can buy commercial horn oil solution, but it is essentially the same exact stuff as WD-40. I don't know where your heard not to oil them....that's really the only way to keep them hydrated. The long term care of those types of horns is the same...just apply a liberal amount to a rag and wipe down once a year. The synthetic oils in WD-40 keep the keratin preserved and helps to no crack, split, or flake.
Rule of thumb....'Oil horns, Wax antlers'.
Joel-BRT