Overo lethal white foal syndrome " "(OLWS) ""in Paint Horse

Overo Lethal White Foal Syndrome (OLWS)


Overo lethal white syndrome is an autosomally inherited disease associated with horse breeds that register white coat patterns. The syndrome is associated with a single amino acid substitution at residue 118 on the endothelin-B receptor gene and occurs in white foals born to American paint horses of overo lineage, specifically the frame overo subtype. Affected foals appear normal at birth but fail to pass meconium and develop severe colic as a result of ileus caused by a functional intestinal obstruction. In the absence of veterinary intervention, death ensues, usually within 24 to 48 hours postpartum. Because there is no treatment for this condition, euthanasia is warranted to minimise unnecessary pain and suffering.
The Overo coat colour is dominant over other coat colours, but the OLWS disease inherits in an autosomal recessive fashion.


Paint Horse and related breed

Trait of inheritance


Test duration

3-5 days after arrival of the sample in the lab


The DNA test is performed out of EDTA blood or or 20-30 hair roots from mane or tail. Test kits can be ordered free of charge. (order-form). If hair is sent in, possibly the genetic material is not sufficient to run the test. In this case it would be best to send in an EDTA blood sample.

Testing procedure

Please send in your sample together with the lab order genetic. Results will be transmitted optionally via post, fax or email. After completion of the test you will receive a separate invoice. Payment can be made via credit card or bank transfer.
Breeding club discounts apply if a copy of the membership card is sent together with the respective samples. Due to administrative reasons the invoiced price can not be altered subsequently.


Please contact our molecular biology team for further questions.

Steubenstraße 4
D-97688 Bad Kissingen

Telefon: +49 (0)971 72020
Fax: +49 (0)971 68546
E-Mail: info@labogen.com


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