What is lethal white syndrome?

Lethal white syndrome is a genetic disorder primarily affecting horses, particularly those with overo coat patterns. It results in foals being born with an underdeveloped intestinal tract, leading to colic and usually death within a few days. Understanding this condition is crucial for breeders and horse enthusiasts to prevent its occurrence through informed breeding practices.

What Causes Lethal White Syndrome?

Lethal white syndrome is caused by a genetic mutation in the endothelin receptor type B (EDNRB) gene. This mutation is inherited in an autosomal recessive pattern, meaning a foal must inherit one copy of the mutated gene from each parent to be affected. Horses that carry one copy of the gene are known as carriers and do not exhibit symptoms but can pass the gene to their offspring.

How Does Lethal White Syndrome Affect Horses?

Affected foals are born with a completely white coat and blue eyes. Internally, they lack proper nerve innervation in the intestines, leading to a condition known as aganglionosis. This results in a non-functional bowel, causing severe colic symptoms shortly after birth. Unfortunately, there is no cure, and humane euthanasia is typically the most compassionate option.

Identifying Carriers: Genetic Testing

Genetic testing is the most reliable method to identify carriers of the lethal white gene. Breeders can test potential breeding pairs to ensure that two carriers are not bred together. This proactive approach can prevent the birth of affected foals.

Why Is Genetic Testing Important?

• Prevention: Avoid breeding two carriers together, reducing the risk of affected foals.
• Breeding Decisions: Make informed decisions about which horses to breed.
• Awareness: Increase understanding of genetic health in horse populations.

Breeding Strategies to Avoid Lethal White Syndrome

To prevent lethal white syndrome, breeders should implement strategic breeding practices:

1. Genetic Testing: Test all breeding stock for the lethal white gene.
2. Avoid Carrier Pairs: Do not breed two carrier horses.
3. Educate: Inform others in the equine community about the importance of genetic testing.

People Also Ask

What Are the Symptoms of Lethal White Syndrome?

Foals with lethal white syndrome exhibit symptoms such as colic, failure to pass meconium, and signs of abdominal pain. These symptoms typically appear within the first 24 hours after birth.

Can Lethal White Syndrome Be Treated?

Unfortunately, there is no treatment for lethal white syndrome. Due to the severe and painful nature of the condition, euthanasia is often the most humane option for affected foals.

Are All White Horses Affected by Lethal White Syndrome?

Not all white horses are affected by lethal white syndrome. The condition specifically affects foals with the genetic mutation associated with the overo coat pattern. White horses with other genetic backgrounds are not at risk.

How Common Is Lethal White Syndrome?

Lethal white syndrome is relatively rare but can occur in breeds where the overo coat pattern is common, such as Paint Horses. The prevalence depends on the carrier rate within a specific breeding population.

What Is the Role of the Overo Coat Pattern in Lethal White Syndrome?

The overo coat pattern is often associated with the lethal white gene. Horses with this pattern can be carriers, making it essential for breeders to test for the gene, especially when breeding horses with overo markings.

Summary

Lethal white syndrome is a serious genetic disorder that can be prevented through responsible breeding practices. By understanding the genetic basis of the condition and employing genetic testing, breeders can significantly reduce the risk of producing affected foals. Educating the equine community about this disorder is crucial to promoting healthier breeding practices and ensuring the welfare of horses.

For more information on related topics, consider exploring articles on equine genetics and responsible horse breeding practices.