Overo Coat Colour in Horses

Overo coat colour is characterised by a white spotted pattern on the abdomen of the horse, and is typically found in the American Paint Horse and the American Pinto Horse. In the UK the term "pied" is more frequently used, although this can include similar colouring caused by other genes. Overo horses have one copy of the overo gene and one copy of the normal gene. Foals which are homozygous for the overo gene suffer from Overo Lethal White Syndrome (OLWS) with defects in the enteric nervous system leading to digestive problems very soon after birth - OLWS is fatal. For more information see "Horse Genetics" by A.T.Bowling (1996. CAB International).

The mutation underlying overo colouring has been identified in the laboratory of Professor J.Mickelson at the University of Minnesota. We have developed a test for overo, based on this information.

Samples should be 20-30 hairs, pulled not cut, from the tail or mane. These should be submitted in an AHT Sample Bag, obtainable free-of charge from the address below.
Samples should be sent together with a completed DNA Testing form and payment for each sample to Genetic Services, Animal Health Trust, Lanwades Park, Kentford, Newmarket, Suffolk CB8 7UU.

Sample Bags are available by phoning 01638 555621 or via e-mail to dnatesting@aht.org.uk. The price of the test is £70, which includes both VAT and the cost of the sampling kit. Further information can be obtained by e-mailing dnatesting@aht.org.uk.