Horses, Donkeys and Pigs float above water when dismounted underwater

Rideable animals float above water when dismounted underwater. If you mount horses and donkeys they correct but if you mount a pig it stays floating until you bring out a carrot on a stick. 

Steps to re-create the issue:

1. Create a 4 block deep water pool
2. Build above the waters surface at least 5 blocks
3. Mount and tame a rideable animal
4. Walk the animal into the water