D-OC predicate: valuable information, but not a prediction of the X-ray result.
You have found an interesting KWPN foal and are reviewing the data. In addition to the pedigree and description, you might also see a D-OC predicate or a genomic breeding value. What does that value tell you? And what does a higher or lower score mean for the foal's future health?
The D-OC predicate is a tool that can support you in your decision. It provides an estimate of the hereditary predisposition for osteochondrosis, but does not predict whether a foal will later show OC or OCD on X-rays.
What is a D-OC predicate?
D-OC stands for DNA predicate osteochondrosis. Based on DNA testing, the KWPN calculates a genomic breeding value for osteochondrosis: the GFW OC. A hair sample is used for this, making the test possible for a young foal.
This breeding value provides information about the hereditary predisposition for OC relative to the KWPN population. For breeders, this is a tool to take that predisposition into account in their breeding choices.
Osteochondrosis, abbreviated as OC, is a disruption in the development of cartilage into bone in a joint. When a fragment breaks off during this process, we refer to it as OCD. Hereditary predisposition plays a role, but conditions during growth and rearing also have an influence.
An expected value, not a diagnosis
The most important thing to understand: the D-OC value is an estimated breeding value, or an expected value for hereditary predisposition. It is not a diagnosis of the joints of the individual horse.
A foal with a low D-OC value may later prove to have no OC or OCD at all upon radiographic examination. Conversely, a foal with a favorable value or a D-OC predicate may still develop abnormalities.
The KWPN also emphasizes this distinction: a low value does not necessarily manifest in the horse itself, whereas a horse with a favorable hereditary predisposition can have OC.
If, for example, you have a horse radiographically examined at the age of three, the previous D-OC result offers no guarantee of a favorable or unfavorable result. A low score does not automatically mean abnormal images. A high score does not guarantee images without abnormalities.
What does a value of 96 or higher mean?
The average of the KWPN population is set at 100. A higher value is more favorable for the expected inheritance of OC. The score is not a percentage: therefore, 100 does not mean '100% healthy'.
In the KWPN explanation, values from 96 to 104 are described as average . From 105 onwards, the expected inheritance is more favorable than average.
A result of 96 or higher is therefore still a good result to include in your assessment . The fact that the predicate threshold has now been raised bij the KWPN to 99 does not suddenly make a value of 96, 97, or 98 a poor result. It is important to consider the true meaning of the value, alongside the administrative threshold for achieving the predicate.
After all, a foal with a score of 98 does not suddenly become a different horse just because the predicate threshold shifts to 99.
What has changed in 2026?
The KWPN has increased the minimum genomic breeding value for achieving the D-OC predicate in mares.
Date of the result | Minimum value for the D-OC predicate in mares |
In 2025 | 96 |
Through 28 February 2026 | 96 |
From March 1, 2026 | 99 |
In this regard, the date of the result counts, not the date of the application. With the higher limit, the KWPN aims to select more strictly based on health. Separate rules apply to stallion selection; nothing has changed in this regard as a result of this amendment.
Mares that have previously achieved the predicate with, for example, 96, 97, or 98, retain it. A previously obtained predicate is therefore not taken away by this change.
What can you use D-OC for?
D-OC helps you take the hereditary predisposition for OC into account. This is particularly relevant if you intend to use a mare or stallion for breeding later on. A breeder can factor this value into the selection of a suitable partner.
D-OC can also be used for mares to meet the health requirement for the Elite predicate. For this, the mare must also meet the other conditions. The PROK predicate remains an alternative route.
When purchasing a foal or horse, D-OC is therefore one of the pieces of information that can help you. How much weight you give this information depends partly on your plans: are you looking for a future riding horse, a broodmare, or a potential stud stallion?
What guarantees does D-OC not provide?
The D-OC predicate confirms that a horse met the applicable conditions at the time of award. It does not provide certainty that:
the horse itself is free of OC or OCD;
X-rays at a later age show no abnormalities;
a horse with a low value later does have abnormal photos;
the horse always remains healthy and free from lameness;
any offspring be free of OC or OCD.
Furthermore, a foal from the same two parents does not automatically receive the same predicate. Each foal inherits a unique combination of genetic material and can therefore score differently from its parents.
D-OC and radiological examination complement each other.
A DNA test and a radiographic examination provide different information. D-OC concerns the estimated hereditary predisposition for OC. X-rays make it possible to assess the examined bones and joints of the individual horse.
PROK is based on meeting the radiological requirements of the KWPN. This is therefore different from a favorable DNA result.
When purchasing, discuss with an independent equine veterinarian which examination is appropriate for the horse's age and your intended use. D-OC can provide additional information, but does not replace that individual assessment.
Look at the complete foal
At Veulentekoop.nl, we view D-OC as a tool to make a more informed choice. Ask for the actual value and compare it with the pedigree, temperament, conformation, movement, and available health information.
A low D-OC value does not rule out good radiographs at three years of age. Nor does a high value guarantee them. And a value of 96, 97, or 98 remains a good result around the population average, even if it no longer results in a predicate under the new standard.
Use the information to support your choice and do not let the assessment of a foal or horse depend on a single number.