Some goats exhibit a peculiar reaction when startled, appearing to “faint” or fall over. This distinctive behavior has earned them nicknames like “fainting goats,” “stiff-legged goats,” or “Tennessee wooden-leg goats.” This phenomenon is not a true faint, where consciousness is lost, but rather a temporary stiffening of their muscles.
Understanding Goats That “Faint”
When a goat with this trait is suddenly surprised or excited, its muscles stiffen, often causing it to fall to the ground. This reaction is a muscular phenomenon, not a loss of consciousness. The goat remains fully aware of its surroundings, even continuing to chew food if it was eating.
This muscle stiffness primarily affects their skeletal muscles, particularly those in their back legs, causing them to suddenly tighten up and then slowly relax. Younger goats tend to fall over more frequently, but as they age, many learn to adapt and can brace themselves or run away on stiffened legs without falling.
The Genetic Reason for Their Stiffness
The stiffening observed in these goats is due to a hereditary condition called myotonia congenita. This genetic disorder affects the skeletal muscles, which are responsible for voluntary movement. It is caused by a specific mutation in the CLCN1 gene, which encodes a chloride channel critical for normal muscle cell function.
Normally, after a muscle contracts, chloride channels open to help the muscle fibers relax quickly. In goats with myotonia congenita, the mutation in the CLCN1 gene leads to a reduced conductance of chloride ions. This deficiency causes the muscle fiber membranes to become hyperexcitable, meaning they continue to fire electrical signals for longer periods than usual after stimulation. As a result, the muscles experience delayed relaxation, leading to temporary rigidity and stiffness. This condition is similar to a human disorder called Thomsen disease and has also been observed in other animals like horses, dogs, and cats.
Life and Care for Myotonic Goats
Myotonia congenita does not cause pain to the goats during these stiffening episodes. While they cannot communicate their sensations, their behavior suggests they are not distressed by the phenomenon, often getting up and resuming their activities as if nothing happened. The primary risk comes from potential falls if they are startled on uneven terrain or from a height.
These goats are generally hardy and adaptable, requiring care similar to other goat breeds. They are known for their docile and friendly temperament, making them suitable as pets or for small farms. Their unique condition means they are less prone to climbing fences or escaping, which simplifies their containment. Myotonic goats are also valued for their heavy muscling, which results in a high meat-to-bone ratio, making them efficient meat producers. The breed originated in the United States in the 1880s and is recognized for its distinctive characteristics.