Dirk Willem Rosie

The KWPN studbook has been selecting for hereditary disorders in equine joints for almost 30 years. In the male population a true selection takes place: stallions can only breed if they meet the criteria. Mare owners can x-ray there broodmares and receive a predicate for soundness on a voluntary basis.


Dirk Willem Rosie

Breeding expert DIRK WILLEM ROSIE worked for the KWPN (Royal Dutch Warmblood Studbook) from 1994 until 2006. During this period he was editor–in–chief of the Dutch equestrian magazine In De Strengen. Today he runs his own equestrian communications company.

Rosie began his career in journalism as an art editor and theatre critic, and his passion for horses initially found expression through his contributions to the magazine De Hoefslag.

While working for the KWPN, Rosie followed a course in genetics at Hogeschool Larenstein in Deventer and wrote a series of extensive articles on population genetics and systematic horse breeding.

In 2004 Rosie was a presenter at the Global Dressage Forum where he offered an examination of how conformation, movement and temperament can contribute to the FEI ideal of the horse as a ‘happy athlete’. Afterwards he wrote a book about the ideal conformation, movements and temperament of the dressage horse. ‘The dressage horse’ is based upon the FEI rulebook, its requirements with respect to the horse. The book also combines the practical knowledge of studbooks and breeders with an extensive survey amongst top riders and the highlights of biomechanical research on dressage horses. An English translation of this book will be published shortly.
Rosie wrote a historic book about Dutch equestrianism at the Olympic Games and about a journey he made by horse and carriage from Holland to St. Petersburg.

Dirk Willem Rosie lives in Haaksbergen, The Netherlands. He breeds show jumpers of whom several have reached Grand Prix level.


The KWPN strategy against skeleton related disorders consists of:
navicular disease
fetlock arthrosis (fore leg)
osteochondrosis (hock and knee of hind leg)

After 25 years of selection it became apparent that the Dutch battle against navicular disease, spavin and arthrosis was successful. Incidence of these disorders in the KWPN population decreased remarkably. The oc- situation however remained the same.

General Genetic Background
From the start the assumption was that the genetic background of osteochondrosis was of a general nature, coming from the total process of cartilage resorption and subsequent calcification-ossification. The idea was that a slight form of oc, harmless for sport horses, would have the same genetic meaning as a bunch of big chips. So: a general strategy against oc in any form would bring genetic progress.

Dutch breeding had to take the loss of very good, very talented, very promising young stallions being rejected just because of a minor irregularity, academic for sport horses. The big German studbooks condoned osteochondrosis to a certain extend, but the Dutch breeders thought they were doing the better job.

Scientific Developments
In the mean time scientific ideas about osteochondrosis developed quickly worldwide. It was indicated that the genetic background of oc is not ‘simple’, that maybe the various forms (from harmless to seriously injuring) would have various genetic backgrounds. The famous Belgian veterinarian dr. Leo De Bakker, working for the Zangersheide stud and Studbook Zangersheide, claimed a genetic relation per joint (stallion A would cause OCD primarily in the knee, stallion B would cause OCD primarily in the hock etc.).

The occurrence of oc per joint was found to be somewhat related with time.

Zangersheide and – on a larger scale – a Hanoverian research performed by the University of Göttingen tried to establish a molecular genetic relation with clinical findings. A breakthrough however is still awaited for.

Dramatic Change in Policy
The insufficiency of the existing KWPN programme and the latest scientific developments worldwide resulted in a dramatic change in the Dutch breeding policy. The KWPN was the first to successfully develop breeding values for jumping, dressage and conformational traits, in 2004 the decision was taken to lay the foundation for a reliable oc breeding value.

Population Scan
At the expense of the studbook 25 random picked offspring from 32 random picked sires were x-rayed for osteochondrosis at the age of 9 months (or slightly older). This operation took place from the fall of 2005 until the spring of 2006. Along with the pictures, measurements of height at withers and the total size of the chest were taken. Together with age these figures will be taken into account, because the assumption is that a relation with development of growth can be found. The ambition of this population scan is to establish a reliable hereditary degree (H²) and sufficiently reliable genetic correlations.

To the pleasant surprise of the studbook, the x-rays of almost all 800 yearlings were produced. The x-rays were classified in a new way, with five divisions from A (no osteochondrosis) to E (several large chips). A ‘quick and dirty’ conclusion is that significant differences can be seen: some sires have their offspring for almost 100 % in the divisions A and B, others only for 50 %.

By the time this paper was published, the agricultural university of Wageningen was in an ongoing process of analysing. Results should be available at the Horse Breeders and Owners Conference in Alberta in January 2007.

Breeding Values
Of course the population scan should lead to the development of reliable breeding values for osteochondrosis. It is likely that all Dutch brood stallions will have these indexes in due time. Whether or not the KWPN will reject the worst progenitors is a decision this democratically organised association still has to take. But from a breeding point of view it would already be effective if these breeding values would be published, so the Dutch breeders can make up their own minds.