Before I continue I would like to point out that these photos may not represent the true conformation of each horse. I am not sure that these photo's represent the true way in which each horse naturally sets up . Many times this is not the true structure of a horse, but the way a handler has set the horse, however we will take advantage of this for the benefit of learning.

One or both hooves toeing out or deviating as far as splay footed, can cause interference with the opposite front leg. In some cases a horse can cause hard or soft tissue damage by hitting the opposite leg. This type of tracking or stance can often be seen in a narrower chested horse. It is also not uncommon to see foals stand and move like this simply because the body has not yet finished growing and widening out, hopefully the youngster will out grow this and straighten out in the fronts. When toed out or splayed foot  is present in the mature horse the joints do not move squarely, putting more pressure on the inside of the knee which can cause stress or strain to ligaments, tendons and joints. The toed out horse can develop splints both from striking the leg and from the extreme pressure to the inside, where the splint bone is located. 

Hoof Angles

1-B shows a pastern that is too sloping which can cause stress and strain to the suspensory ligaments, tendons and fetlock joint. 1-C shows a closer to straight up pastern, the extreme of which could be seen on a clubbed hoof. This type of angle sends all weight of the fronts straight down into the hoof. This causes little to no shock absorption, depending on the degree. The heels of these horses tends to be longer to keep a straight line in the pastern to the hoof. Often these horses have a shorter pastern and tend to have a shorter, choppier gait. It is not uncommon to see a horse tend to have or easily get a contracted heel (also can be cause by improper trimming and shoeing) which in turn causes internal pressure to the soft and hard tissue inside the hoof.

Broken Axis as shown in 2-A through 2-C is when there is no straight line through the pastern continuing through the hoof. This can be downward as shown in 2-A and 2-B or upward as shown in 2-C. The break in the angle being at the coronary band. This can be structural, but is also so very often seen in many of the gaited breeds due to specific trimming and shoeing to effect gait in an individual. Long toes with short heels being the most common trimming method used to break up an undesired timing of gait. In the case of a heel not growing, a  wedge pad would be more desirable to correct  angle to pastern. This is preferable over a turn back on a shoe which can create a hard concussion when the hoof hits the ground and can often cause sore heels.

In some gaited breeds it is very common to see 2-A which is considered acceptable, to those breeds, as long as the pastern does not break below level at set down of the hoof. In any other breed this is coon footed and should be considered as such in any gaited breed. It is a structural defect and does not support the pastern correctly. The  pasterns on theses horses are many times too long. This can be a cause of broken sesamoids, stress and strain to the  fetlock joint, flexor tendons, suspensory ligaments and to the joints between the cannon bone and P1, between P1 and P-2. In some cases owners are trying to correct this by trimming with a steeper angle hoof  with a shorter toe and longer heel. These methods  just create stress in a different way and it is common to see some horses knuckle over forward at the fetlock when the hoof starts foreword and set down (if it is a horse that does not have the long pastern but the pastern does stretch down to a broken angle at  complete set down) creating again joint stress and change of gait that is not natural to an individual.

Breakover

#1 shows the ideal breakover in which the horse makes a nice arc in the lift off and set down of the hoof. 
#2 shows the break over of a straighter up and down angle of the hoof where at the start of lift off it arcs and then drops down at the half way point sending the weight straight into the hoof causing greater concussion to the hoof and making for a short choppier stride. 
#3 is the long toe and low heel. At the half way point the heel will start to drop because the toe has to lift off sharply and more to clear the ground at which point the heel will be over extended causing stress to the joints and soft tissue.

It is rare to see the ideal in any horse from front to back of the horse. This is what makes each an individual. The terms and standards for ideal gives us a starting point in evaluation. It is when a deviation extends to the point of detriment to a horse's well being if that individuals limitation are not recognized and utilized correctly that we must take care. It is then that we as the owners are short changing a horse of having the chance at a long useful life.

In some cases these deviations occur naturally from birth but often it occurs due to improper care through out the growing years. Inconsistent or incorrect hoof care or lack of funds comes to mind first among other reasons.

I feel it is so important to get any corrective work done early in their youth but be realistic in what can be corrected. In some instances it can be due to a set in structure problem. Trying to correct some deviations can do more harm than good. Consult a veterinarian or farrier for help.

When trimming and shoeing do what is correct for the horses natural angles, balance the hoof from side to side and lastly remove excess toe. Long toes are not necessary to achieve a natural gait when it is developed through strengthening and teaching a horse to carry it's self in the correct frame for it's structure, while carrying the weight
of tack and a rider.