All horses, regardless of when they were actually born, are considered to have a common birthday of January 1. This is one of the reasons most horsemen don’t like their foals to be born late in the year: Even if a foal is born on December 31st he or she will have their first birthday the very next day.

So there’s your answer, we are all celebrating our horse’s birthday on 1st January regardless - assuming we don’t have a hangover of course!