Why risk salmonella? There are many equine specific coat supplements.
The contents of eggs are normally bacteria free. The salmonella would come from using an egg with a dirty shell with which the albumen and yolk has come in contact with. Eggs bought at grocery stores go through a cleaning process before they are put in the carton so he risk is very low. Eggs bought from farmers ect. Have usually not gone through the cleaning process however that doesn't mean they carry the bacteria but could carry a higher risk of it. I have heard of using them before as a feed additive for horses but I don't think that my current horse would touch his food if I were to try it. To me is sounds like a lot of hassel and mess. Could you imagine how nasty the feed pan would look?