I have a draft mule that on her front feet the heels are splitting. Also the heels appear to be contracted a bit. What can I do for this?

Can you trim a lot more heel on a mule than a horse?

Ball park, what is the trimmed length of a 1300 lb. mules hoof? Is it the same for front and back?

I wish it were so easy to put the rules for horse, mule and draft trimming into simple enough terms that I could answer your questions exactly. Unfortunately, what you are wanting to know comes only from lots of exposure to competent farriers who can explain what they are looking at when the trim a foot. "In general" a mule or donkey will have a lot more heel than a horse, and should be left that way since it will correspond to the natural angle. The trimmed length should be somewhere between 3.5" and 4" in most cases, but that has a lot to do with exatly where you are measuring to. It is not always the same from front to hind, depending on the wear and growth patterns. If the heels are contracting, this is usually from an animal trying to use the heels less from soreness. This will cause atrophy. If they are contracting, I would get some professional farrier and/or vet help to make certain that you are not dealing with a lameness. As to the heel splitting, I would need to see it to comment on it. My best advice to you is to hire a good farrier, or better yet, become trained to be a good farrier. It is not an easy trade to learn, but the rewards that come from helping horses in pain are immense.