Fainting goat
An American breed known for myotonia congenita causing stiffening or falling.
The myotonic goat, an American breed, is often called the fainting goat, Tennessee fainting goat, or nervous goat. It inherits myotonia congenita, a condition causing stiffening or falling when startled. Other names include falling goat, stiff-legged goat, and Tennessee wooden-leg goat. Four such goats arrived in Tennessee during the 1880s.
Quick Facts
- Origin
- United States (Tennessee)
- First brought to tennessee
- 1880s
- Height
- 43 cm (1 ft 5 in) to 64 cm / 2 ft 1 in
- Weight
- 27 kg (59.5 lb) to 79 kg (males up to 90 kg / 198 lb)
- Conservation status
- At risk (2019, DAD-IS)
- Genetic mutation identified
- 1996
Facts from the source article.
History
Fainting goats first appeared in Marshall County, Tennessee, during the 1880s, and most myotonic goat breeds today trace back to a small number of animals from that area. White and Plaskett documented the goats in five Tennessee counties: Marshall, Giles, Lawrence, Maury, and Coffee. A farmer in Texas brought some from Giles County just to prove to his neighbors that the goats were real. These goats couldn’t leap over standard fences, so they would dig under them through ground holes, much like pigs. This trait made them more appealing when stone walls were common for containing livestock. A buck goat from Canada also ended up in Marshall County. The A. & M. College in Texas had a zoo from 1926 to 1927 that featured a myotonic goat. Dr. White reported seeing several fainting goats in Egypt during the summer of 1929, between the Suez Canal and Palestine’s border, and he sent some from Tennessee to Professor Nagel at Germany’s Nervous Disease Institute for research. The fainting was first recorded in scientific literature in 1904, and it was labeled congenital myotonia in 1939. The specific goat gene mutation responsible for the muscle stiffness was identified in 1996. Brown and Harvey’s 1939 experiments with myotonic goats greatly advanced the understanding of myotonia’s physiology and shaped later theories about its causes.
Characteristics
Myotonic goats vary considerably in characteristics compared to other goat breeds, with distinct differences in head and body formation. They have a wide body and heavier mass, with increased muscle mass and a broader build. Slightly smaller than standard goat breeds, they stand 43 cm to 64 cm tall and weigh 27 kg to 79 kg, with males reaching up to 90 kg. Broadness is evident through the back and shoulders due to muscle density. Their eyes are large, prominent, and set in high sockets, sometimes called bug-eyed. The head is medium length with a broad muzzle and broad jaws, and the face is usually straight or convex. Ears are normal-sized, close to the face, and have a ripple halfway down their length. Horns tend to be large with 1-2 inches between them. The neck is muscle dense and more round than that of dairy breeds, with wrinkled and thick skin on many males, and can run horizontally so the head is lower. Hair may be short or long, with some individuals producing cashmere in colder months; coats can be any color or pattern. Myotonic goats are vigilant and quieter than other goat breeds, and are noted for high trainability, stiffness, good adaptation to low-input farmland and foraging, and cross-breeding producing hybrids with physical strength and good health.
Cause of "fainting"
Myotonia congenita in fainting goats stems from a problem with a chloride channel found in skeletal muscle, specifically the one known as CLCN1. This condition can be passed down in two ways: as an autosomal dominant trait that does not always show up fully, or as a recessive trait, which leads to different levels of severity. In goats that have the disorder, a single missense mutation in the CLCN1 gene swaps the amino acid alanine for proline. That tiny change makes the chloride channel less able to conduct chloride ions. This mutation sits within a stretch of seven amino acids that is also present in similar channels in humans and rats. The nucleotide change causes proline to replace alanine at the carboxyl end of the goat’s chloride channel. In affected animals, there is a shift of +47 millivolts in how the channel activates, meaning fewer open chloride channels are available near the resting membrane of skeletal muscles. This drop in chloride production at the molecular level explains the muscle stiffness. The mutation slows down muscle relaxation after an involuntary movement, and the muscle fibers tend to fire off repetitive action potentials and after-discharges. The extra excitability comes mostly from the lack of chloride permeability. The condition also brings a notable rise in fast isomyosins across all muscle types. The muscle fibers of myotonic goats are highly resistant to electrical flow, matching the blocked chloride conductance. Normal goat muscle can be made myotonic by using drugs that block chloride conductance or by swapping in an anion that cannot pass through a semi-permeable membrane. Isolated intercostal muscle from affected goats shows clear differences from normal muscle in how its resting membrane resistance and potassium efflux depend on temperature. These differences help explain why the myotonia gets worse when the affected muscles are cooled down.
Relationship to humans
The muscle disorder seen in myotonic goats mirrors a human condition called congenital myotonia, which is a chloride channel problem that causes muscles to relax slowly. This issue stems from changes in the skeletal muscle chloride channel gene and can be mild or severe. In one study, researchers used human muscle biopsy samples and applied Periodic acid-Schiff staining with diastase digestion, finding PAS-positive material inside the fibers of myotonic goats. These goats are not a top choice for sustainable meat production. Goat meat production typically relies on maternal breeds that thrive in tough conditions, but standard methods cannot measure the maternal fitness of myotonic goats. To get around this, scientists compared 80 myotonic goats with Spanish, Kiko, and Boer goats, looking at fecal egg count and packed cell volume. Myotonic goats had lower body weight and lower fecal egg counts but higher packed cell volume than Boer goats. Weaning rates, annual kidding rates, doe retention, and kid crop weaned were similar across all breeds, though myotonic goats had the lowest fecal egg count. This suggests they are less suited for meat production in challenging environments. In 2019, the Food and Agriculture Organization of the United Nations listed the myotonic goat as "at risk" in its DAD-IS database. The Myotonic Goat Registry stresses the importance of preserving the breed, pointing out traits like calm behavior, resistance to parasites, strong mothering skills, and the fainting behavior itself. These goats rarely jump over fences taller than half a meter, so farmers can use shorter fencing. The registry also tracks percentage myotonic goats to keep an accurate record, helping identify purebred animals for meat, milk, or as pets.
More in Conservation Priority Breeds of the Livestock Conservancy
Spotted an error? Know more?
Reader corrections go straight into our review queue. Suggest an edit · How this site is sourced