Einstein isn’t technically the smallest stallion, but he is the smallest healthy horse. Both of his parents were small miniature horses. Genetically, Einstein is perfectly normal, with all of the desired proportions of a typical miniature horse.
The current record holders, Thumbelina and Bomel, are smaller than him by a few inches, but both of them have dwarfism. Mini horses with dwarfism have numerous health issues and often require surgery to survive.
Einstein, however, is perfectly healthy. When he was 2 months old, he required a historic surgery after a life-threatening spinal cord injury, but he made a full recovery.
