Cant ride my horses or any animal i had prior to and update that happened 1 month ago

After an update to Minecraft that happened 1 or 1 1/2 months ago i wasn't able to ride any of my horses or any other rideable animal i had prior to the update, i can ride new freshly spawned animals but i need and want to use my old animals which is around 5 horses and llamas. Please help this is pretty annoying

From, an avid minecrafter

To: The great people at Mojang