There have been two bug reports regarding this issue so far MC-260974 which was fixed in the latest snapshot and MC-261909 which was marked as a duplicate of MC-260974  {}how ever I would like too point out that in it is referring to many more mobs than just the skeleton horse the spider jokey the zombie horse and the normal horse. in MC-261909 it also refers too mobs such as pigs, lamas, striders, etc... and in the recent snapshot only the ones reported in MC-260974 were fixed. Please do not mark this bug report as a duplicate as it is not, unless all of these have already been fixed in an unreleased version that I am not aware of.