Lavender foal syndrome

Why LFS affects both coat pigment and the nervous system

MYO5A helps move small components inside cells. The protein it encodes works as a motor, contributing to the movement of pigment-containing structures and to normal nerve cell function. This helps explain why one inherited change can affect both coat pigmentation and the nervous system.

Researchers identified a small deletion in MYO5A: a piece of the DNA sequence is missing, disrupting how the gene’s instructions are read. The 2010 discovery study connected this change to LFS. The color itself does not make the foal ill; coat dilution and neurological dysfunction are consequences of the same underlying defect.

References [1] · [3]

LFS can prevent a foal from standing or nursing from birth

Affected foals show neurological problems from birth. They may be unable to stand or even maintain a normal upright position on their belly. Reported signs include stiff paddling limb movements, seizures, excessive extension of the neck and back, and involuntary eye movements.

Some retain a suck reflex, but that does not mean they can rise and nurse normally or that the condition will resolve. These signs require urgent veterinary assessment. Their intensity can vary, yet the LFS described here remains a severe, fatal disorder. It should not be dismissed as normal newborn unsteadiness or assessed from a single sign alone.

References [2] · [4] · [3]

A pale coat does not establish a diagnosis of LFS in a foal

The coat is often described as lavender, silver or pale pink, but descriptions also range from very pale gray to light chestnut. The name reflects an appearance commonly observed in affected foals; it is not a precise shade that can be recognized with certainty in a photograph.

Many horses have pale coats for other genetic reasons and do not have LFS. Equally, describing the color cannot replace examination of a newborn with neurological problems. The names LFS and CCDL, short for coat color dilution lethal, are used for this MYO5A-associated condition. Neither name makes visual color assessment a diagnostic test.

References [2] · [3] · [1]

Which horses have been found to carry the LFS variant?

LFS is best documented in Arabians, particularly Egyptian lines. It has also been reported in other Arabian breeding groups, and testing is relevant to Arabian crosses. Calling it exclusively an Egyptian Arabian disease would therefore be misleading.

Published frequencies depend on the horses sampled, the date and the families studied. They do not establish one horse’s status. A carrier adult can have an ordinary-looking coat and be unaffected by this disease. Its appearance, ancestry or previous production of a healthy foal cannot rule out carrier status. A population list is not proof that the variant is absent from every other group.

References [3] · [1] · [4]

Distinguishing LFS from other causes of seizures or difficulty standing

A foal unable to stand may have another problem, including the consequences of oxygen deprivation around birth or an injury. Difficult delivery can also accompany LFS and complicate interpretation. Automatically blaming the delivery for every sign can therefore hide an inherited cause.

The vet considers the birth history, neurological examination and suitable further investigations. Some routine blood results may be normal despite LFS. Testing MYO5A helps confirm the diagnosis but does not investigate every cause of weakness or seizures. Care for a sick newborn should not wait for the laboratory report; clinical assessment and genetic investigation answer related but different questions.

References [2] · [3]

What the three LFS DNA test results mean

The laboratory looks for the MYO5A deletion responsible for LFS and reports how many copies of that variant it detected. One copy identifies an unaffected LFS carrier. A foal with two copies, one inherited from each parent, has LFS. Reports often use N for a copy without the tested variant and LFS for one with it. Read these symbols alongside the laboratory’s own key; N does not mean the MYO5A gene is missing.

A negative result addresses that variant, rather than all newborn diseases or all causes of pale color. Correct animal identification and the laboratory’s sampling instructions also matter. A properly identified genetic result gives specific information; it is not a general assessment of neurological health.

References [3] · [4] · [1]

What care is possible for a foal with LFS?

Veterinary care can sometimes ease individual signs temporarily, including seizures, while assessing the foal’s immediate needs. It does not correct the genetic defect. There is no established cure for LFS, and affected foals die or are euthanized shortly after birth.

Decisions depend on examination, suffering and the outlook for the individual foal, in discussion with the vet. A brief improvement does not show that the disease has disappeared. This grave prognosis concerns affected two-copy foals, rather than one-copy adult carriers, which do not develop this recessive condition. The distinction prevents a breeding result from being mistaken for a diagnosis of an ill adult.

References [2] · [3] · [4]

Testing both parents to prevent a foal with LFS

LFS is autosomal recessive: both sexes can be affected. If the mare and stallion each carry one copy of the MYO5A variant responsible for LFS, every conception has a 25% chance of an affected foal with two copies of that variant, a 50% chance of an unaffected carrier with one copy and a 25% chance of a foal without the variant. Four pregnancies do not have to produce that exact distribution.

For the tested variant, a carrier mated to a confirmed non-carrier cannot produce a two-copy foal, although offspring can be carriers. Knowing both results allows breeders to avoid at-risk combinations without automatically excluding every carrier from a population. Keeping and sharing reports also supports decisions in the next generation. A normal-looking breeding animal should not be assumed clear without genetic information.

References [3] · [2] · [4]

Questions about the condition: Lavender foal syndrome

Scientific sources about the condition: Lavender foal syndrome

This article brings together the research and the university and laboratory resources listed below. Numbers after each section link to the references used. Sources consulted in November 2026.

1. 1.
   Brooks et al. (2010) — Identification of a deletion in myosin Va responsible for Lavender Foal Syndrome

   PLOS Genetics · Cornell University · Research

2. 2.
   Lavender Foal Syndrome

   UC Davis Center for Equine Health · University resource

3. 3.
   Lavender Foal Syndrome: genetic test

   UC Davis Veterinary Genetics Laboratory · Test documentation

4. 4.
   Lavender foal syndrome: clinical presentation and inheritance

   Practical Horse Genetics · Test documentation