Untrained is a pet trait featured in The Sims 3: Pets. This trait is only available for horses.
Untrained horses aren't accustomed to having saddles and Sims on their backs. They need to spend some time saddled and being ridden by a trusted Sim to accept any rider.
Attributes[]
Horse requires more relationship to Saddle or Ride them.
Horse receives a price penalty if you are selling the Horse.