What I expected to happen was...:
Crossing water with saddled Horse, too deep of water usually results in dismount and horse going nearest land.

What actually happened was...:
Horse completely disappeared with saddle. No drop, no EXP dropped.

Steps to Reproduce:
1. Ride horse (I was in 3rd person) Full health
2. Cross water (current river was ~10 blocks deep.
3. Horse disappears with any gear/ saddle. I have crossed water before always resulting in dismount and horse moving to nearest land.