How DNA Parentage Testing Works In Horses

DNA parentage testing compares a foal's genetic profile with those of its stated sire and dam. If the foal carries markers that neither parent could have passed on, that parent is excluded. If every marker fits, the parentage is confirmed.

What the laboratory actually does

A foal inherits half its DNA from each parent. A laboratory reads a set of markers in the foal, the dam and the sire, then checks whether each foal marker could have come from the named parents. One veterinary genetics laboratory at UC Davis, in the United States, reads 15 microsatellite markers and also checks a sex marker. Software then compares the profiles.

Samples and what they cannot show

Hair is the usual sample. The same laboratory asks for 20 to 40 hairs with roots, pulled from the mane or tail, and tail hair only for foals. The test does not identify a horse's breed. It only answers whether the named animals could be parent and offspring.

Microsatellites and SNPs

Microsatellites have been the long-standing standard. A published Thoroughbred study notes that the International Society of Animal Genetics recommends at least 12 of them. Newer panels use single nucleotide polymorphisms, or SNPs. In that study, a 516-SNP panel gave an exclusion probability above 0.9999, against 0.9870 to 0.9943 for the microsatellite panels. SNPs also mutate far less often. The authors still describe their work as a comparison, so laboratories and registries choose their own methods.

What the rules say depends on the country

Registries set their own requirements. The American Quarter Horse Association, for example, requires parentage verification for foals produced from frozen semen. That is a United States rule. Nigeria's own rules are being set, so nothing here should be read as a Nigerian requirement.

What this means for the programme

• The programme crosses Sahel mares with thoroughbred sires, using frozen semen.
• Each pony is microchipped and has DNA parentage on file.
• The Nigerian Sport Horse Society, which will keep breed records, is being set up and has not yet launched.
• The programme is in formation. No ponies are for sale and no results are claimed yet.

Frequently asked questions

Can a DNA test prove who the sire is? It confirms that a named sire is consistent with the foal's profile, or excludes him. Confirmation is a matter of probability, which is very high with a good panel.

Why test the dam as well as the sire? Testing both lets the laboratory see which markers came from each side. This makes an exclusion easier to interpret.

Is hair or blood better? Hair with roots is widely accepted and simple to collect. Individual laboratories state which sample types they take.