Fainting goats have a muscle condition which is called myotonia congenita. Myotonic animals have a change in some of the channels that occur in the outer membranes of skeletal muscle cells. These channels provide for the transfer of certion ions that control muscle relaxation & contraction. The result of this is that when muscles fire rapidly the animal cannot relax, resulting in a prolonged contraction.
Myotonia is a painless condition. It is strictly muscular, and does not involve the nerves or the brain. The animal does not truly "faint" in any sense of the word. They never lose consciousness, they remain fully awake. Some myotonic goats rarely exhibit the condition while other goats are consistently myotonic. In most goats it is only exhibited when they are startled, excited or stepping over a barrier. The younger goats tend to fall over easier, as the older goats learn to keep their balance.
Fainting goats are highly parasite resistant. They are very feed efficient browsers. They are able to maintain health and strive on smaller quantities of feed than other breeds of similar size. They have a slow growth rate. They are calm and docile. They are excellent mothers, rarely needing assistance with cleaning or attending their kids.
Tennessee Myotonic Goats are sometimes referred to as Fainting Goats, Nervous Goats, Stiff-Legged Goats, Wooden Leg Goats, Texas Meat Goats, Fall-Down Goats, etc.