What do you do with a pony that is 1/4 to 1/2 inch over a small, medium or large size? Is the measurement really exact?
Yes, it is. We have one pony showing who’s measurement card is 13.1 1/8 and another one at 14.1 7/8.
In my opinion, if a pony is slightly over height, it really depends on the individual pony in regards to whether you can get them to “measure” or not. If you have the chance to speak with a few pony hunter owners and trainers, there are an abundance of tips and tricks that can be used to help get a pony to measure. This can range from exercising them before the measure in order to relax the withers, pull the shoes for measurement, shave the withers, etc. The most important element for a pony who is a hard measure is to practice, practice and practice measuring at home so that they are 100% comfortable and relaxed when being measured, no matter the time and place. If a horse or pony is tense when they are measured, the height will almost certainly be taller than expected.
1/4 inch can be just the Pony stiffening up, being fresh, cold, scared or needing its feet trimmed or shoes pulled. Which is perfectly legal and safe for the Pony. 1/2 inch is pushing it but might still be doable with a good handler and a lot of pratice swinging the stick over and placing the level on the wither.
And, yes, the measurement is really exact so if you are close, you should seek pro advice and hire one to present the Pony for measure. Yeah it costs but it makes a huge difference in how competitive the Pony can be and hence it’s worth. Unless it’s a one in a million superstar, it’s pretty important.
Assuming it does not have a permanent card already? Correct?
Yes, it does not have a permanent card. Thank you very much for your replys Daventry and findeight. I will use all of your suggestions and hopefully have a shorter pony. 
measure right after its hooves have been trimmed (no shoes), stand on soft level ground, and get the pony to relax.
