Are there any clues to suggest that your horse is a particular type?
Apart from trial and error. Obviously I imagine when breeding then the sire/dams history can have a strong indication.
Do the weight or build or anything else point to one or the other?
In real life you can have a horse that looks like a chaser or is built like a strong hurdler.
I know it's close to SO5 (highlight of my 2012) in which I believe there are extended and more detailed horse attributes.