I have a short SH she is 14.3. Where is the cutoff between the PON and the SH. I would like to breed her back to a PON and wondering if I use a Stallion that is 13.3 or under will raise the chances of a PON foal?
In all honesty, it's just luck xD You can definitely get a PON from her. I bred a 15 hand SH mare with a 14.2 PON stud and got a PON filly. I got lucky but to better your chances use shorter studs.