How to read a thoroughbred pedigree
A pedigree is a family tree. Once you know how it is laid out, you can see in seconds where a horse comes from and what its relatives have done.
“By” and “out of”
A horse is described as by its sire and out of its dam. In the EQS sample report, Mystique Moon is “by Shamardal out of Celestial Girl (by Dubai Destination)”. The sire is Shamardal, the dam is Celestial Girl, and the name in brackets is the dam's own sire, the damsire.
How the chart is laid out
The sire's side is the top half of the chart and the dam's side is the bottom half. Each generation doubles: two parents, four grandparents, eight great-grandparents, and so on. An EQS report shows the tree as far as great-grandparents, which is 14 ancestors in all.
The sire line
Follow the sire of the sire, and then his sire, and you have the sire line. In the sample, it runs Shamardal, then Giant's Causeway, then Storm Cat. Breeders talk about a horse “belonging to” a sire line because stallions pass on traits, and because lines are used to group stallions with similar profiles.
The dam's side and the family
The dam, her dam and her dam's dam make up the female family. Buyers study this closely. A dam who has produced winners, and a family with stakes winners, is a positive sign. This is where black type matters most. See what black type means.
Why the damsire matters
The damsire, the sire of the dam, is the most influential male on the bottom half of the chart. Statistics for damsires are tracked just like those for sires. In an EQS report you see how the damsire's progeny perform against the database median, alongside the sire's.
The letters after a name
Letters in brackets after a name, such as USA, GB, IRE or FR, are the country where that horse was foaled. They can tell you where a family has been bred and raced.
Line-breeding and inbreeding
When the same ancestor appears more than once in a pedigree, the horse is line-bred to it. It is written as two numbers, such as 3x4. That means the ancestor appears in the third generation on one side and the fourth on the other, counting the parents as the first generation. Close repeats are deliberate in many breeding plans, and are worth noting when you compare horses.
What if the tree has gaps?
No database holds every ancestor. Where an ancestor is missing, the EQS report marks the slot not in EQS and tells you what share of the tree it holds, for example 93% in the sample. That way you know how complete the picture is.
A pedigree is a guide, not a prediction
Pedigree shows the potential in a horse's background. It does not decide what the horse will do. Read it alongside the horse's own racing record, the performance of its sire and damsire, and its dam's other foals. An EQS report puts all of these together.
See it in a real report
An EQS horse report puts all of this in one place for any thoroughbred. See a sample report, read the methodology, or buy a report.
More guides
- What is black type in horse racing?What the term means, which races count, how it appears in a sales catalogue, and how to read a black type figure.
- How to research a yearling before a saleA step-by-step approach to the catalogue page, the sire and damsire, the dam's produce record and sales history.