I ride jumpers and for me, there are quite a few faults that are real deal breakers.
back at the knee. As has been said it is a very serious fault that puts incredible strain on the tendons. The leg has a backwards curve to it where the middle of the knee falls behind the line from middle of shoulder to middle of fetlock. Ideally you want straight and correct forelegs.
Toed out in the front legs. I'm not a hundred percent sure WHY it's a deal breaker for me but if the horse is significantly toed out in front and the legs themselves are straight at the top then no thank you. The direction of the toe CAN be indicative of incorrect hoof balance which is where you need the experienced horseperson.
Upright shoulders - they limit reach and tuck over fences, and they limit the extension of the stride. The horse may be choppy and uncomfortable to ride. Ideally you want a shoulder with 45 degrees of slope from the vertical, though more is permissible.
Upright pasterns - limits shock absorption and therefore increases concussion on both horse and rider. Increases the likelihood of arthritis in the horse.
Low fetlocks/pasterns TOO sloped - this is a weakness increasing the likelihood of tendon and pastern injury, particularly if the horse is participating in high-impact sports such as jumping or galloping. It provides a smoother and more comfortable ride but is not ideal in a performance horse.
Long pasterns/cannons - a weakness. The longer the bone is, the more likely it will be to break. High-impact sports are a no-go.
Downhill built - the rump is higher than the shoulder, forcing the centre of gravity forwards. It puts more weight on the horse's front end therefore increasing the strain on the forelegs and front hooves, and as the front legs already carry 60% or more of the horse's weight this is undesirable. It also makes it harder for the horse to push with its hind legs, thus making jumping more difficult, and limiting collection and true extension in dressage.
Post-legged - the horse is overly straight through its hind legs with not much angle to either hock or stifle. This limits forward reach of the hind leg, makes for an uncomfortable ride, and severely limits scope over fences. It also increases the concussion on the horse's joints.
Base narrow - the horse stands with its hooves very close together and in severe cases may stand on itself. This CAN be a hoof balance issue but is more commonly conformational. The horse is far more likely to hit itself as it moves and is likely to have limited lateral reach, therefore limiting its dressage potential. It may paddle (swing the lower leg outwards) instead of coming in close as it moves.
Base wide - the horse stands with its hooves farther apart than necessary. The leg, when viewed from the front or behind, should sit on a line dropped from the centre of the leg vertically to the ground. If the horse stands wider than this, it is base wide. A base wide horse will not move straight and true and is therefore more likely to injure itself.
Neck ties in low - the horse has a low head carriage and the neck meets the chest and wither lower down than ideal. This is desirable in some disciplines but not in jumping or eventing as it limits the horse's ability to truly collect, and tends to put the horse's weight onto its forelegs.
Bull necked - don't get me wrong, I love a nice solid neck, but being 'bull necked' takes it to the extreme. This increases the weight on the forelegs and makes the horse more inclined to travel off balance with its centre of gravity forward of the rider.
Light on bone - this is the BIG one. Light on bone means the horse is not solid/strong enough through its leg bones to carry the weight of the animal on top of them. In high-impact sports it vastly increases the chances of a fracture.
Small hooves - also big. If the hoof is too small for the size and build of the horse it is more prone to concussion laminitis, navicular disease, and other disorders of the hoof, as it is not able to distribute the horse's weight correctly. I like a nice large hoof that is correct in structure and made of good hard horn. Ideally the hoof will be free of chips, cracks and unsoundnesses, and preferably not shod, as a shod horse costs a lot more to keep. I would rather have a horse shod because of the level it is showing at than a horse shod because it is not sound barefoot.
Large scars on the lower legs - this is NOT purely cosmetic! As a showjumper my horses' legs are at high risk of impact and the skin of a scar is only 70% as thick/strong as unblemished skin. If a scar is re-opened it is weaker still. If I can reduce the risk of my horse injuring himself if he knocks a pole then I will.
I haven't even LISTED anything to do with the back (long back is a no, overly short back is also a no) or the overall balance of the size of shoulder/barrel/hindquarter, OR the depth of the girth or anything like that! As a jumpers rider, I need a horse that is basically correct. I will excuse minor faults that do not affect jumping ability because no horse is perfect, but the basics need to be there. Good correct shoulder, correct hindquarter, nice deep and broad chest (heart and lung room, very important), and correct legs are first and foremost for me. Nice open nostrils are also important as in my discipline the horse is working hard so must be able to breathe in large amounts of air easily.
Unattractive heads are excusable performance-wise for a showjumper as the horse is judged on performance, not appearance... but I won't buy a horse that I don't think is beautiful, because I do not want a horse that I look at and think 'eww, ugly face' or anything similar.
Now, I actually have a horse with a few of the faults I have listed as deal-breakers! Monty has HUGE scars on both his hind legs, from fetlock to above the hock... his pasterns are almost vertical... he has HORRIBLE feet... and his shoulder is more upright than I would like! I had to excuse some of these faults if I wanted to be able to afford an experienced jumping horse with the temperament I was looking for.
If it's your first horse temperament is first and foremost. You don't want a horse that's going to break down in a month's time (I have a friend who had that happen!) but as a first horse it doesn't have to be pretty or talented or even particularly correct - just sound and sane and good to ride!
Last edited by blue eyed pony; 11-14-2011 at 08:05 AM.