When buying your Falabella you must consider its conformation. Too many people are putting too much emphasis on size (the smaller the better) and pay little or no attention to the fact that the confirmation is altogether wrong. Bad conformation will cause various problems such as premature arthritis, difficult breeding and possible pain and depression.
There are many good books that will tell you about the correct conformation of horses, but there are other points that occur in all miniature horses that they will not mention in your average book. The legs should be longer than the depth of the girth. The head should not be longer that the length of the neck. The overall picture of the horse should fit into a square rather than a rectangle, although a longer body for a mare is often an advantage if you are considering breeding from her, but again the legs must not be shorter than the depth of girth.
Another cause of faulty conformation is congenital abnormalities; the most common one affecting miniature horses in dwarfism.

This is something that occurs in all mammals and means that the individual is noticeably smaller than the others of its kind are. In miniature horses it is a debilitating shortening and twisting of the skeleton.
Some characteristics of dwarfism in miniature horses are:

Short stature - Very short and sometimes deformed limbs, the legs do not grow or grow unevenly causing crooked legs. Cow hocks are often a problem as the fibula is full length, these problems can lead to premature arthritis.

Undershot jaw - This is where teeth on the bottom jaw protrude beyond the teeth of the top jaw.

Large bulging forehead - Making the face look very dished with a turned up nose, leaving the nostrils set high up on the face, the neck may also be very short.

There are over 200 variations of dwarfism ranging from very mild where the horse can lead an active near normal life without pain, to very severe where the foal is unable to stand, let alone drink from its mother. In these cases it is kinder to have the foal put down as often if it does survive a few months it will possibly die later due to its internal organs being affected. Having a foal put down is a very hard decision to make, you must always think first of the foal and whether it will be suffering if kept alive. I unfortunately have had to make this decision with my first Falabella foal. Neither of the parents showed any outward signs of dwarfism and since then, I have used a different stallion to that mare and have been able to produce normal healthy foals.

As Falabella numbers grow - and with the honesty and co-operation of breeders - it will be possible for the BFS to use DNA test to find this recessive gene. It should then be possible to select your stallion accordingly to help avoid this very distressing condition.