In the new 1.11 snapshot (16w32a). When spawning in a Horse/Mule from a Spawn Egg, then trying to ride it by right-clicking crashes the game. For me at least Right-clicking on Donkeys, Skeleton and Zombie Horses does not crash the game. But the other people on my server crashed due to right-clicking on these animals.
Environment
Java Version: 1.8.0_25, Oracle Corporation
Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
Linked issues
is duplicated by 7
MC-106052
game crashes when trying to breed horse and donkey
Resolved
MC-105957
Ride Donkey and Mule crash the game
Resolved
MC-105999
Potential crash when attempting to tame a horse
Resolved
MC-106007
When riding the mule and donkey crash the game
Resolved
MC-106015
Donkey Crash
Resolved
2 more links
Can confirm for donkey and mule; cannot reproduce for regular horses, zombie horses, and skeleton horses.