WB + TB and other breeds research--from Hannover (In German)

[vineyridge]

This could very well explain the Verband's feeling that TB genes are critical in modern WB breeding.

A kind COTHer sent me the abstract of this dissertation from Hanover. I can't read German at all, so perhaps one of our German speaking members can see if it says what it seems to say in the English abstract, which is that TB and Arab genes correlate positively with soundness in WBs in Hanover.

Here is the German paper:
http://elib.tiho-hannover.de/dissertations/meinersf_ss04.pdf

[BravAddict]

Yes, but much of those pages contain information for people who might like to repeat the study. Most of us here will be interested in the "discussion" section.

[vineyridge]

Some of the COTH members are native German speakers and could read and see if the Englisch abstract accurately depicts the study.

All I would be able to understand, quite frankly, is the introduction, a description of the study's methodology, and the discussion/summary--which all seem to be in the abstract, which I will now post:

Abstract (englisch)
The purpose of the present study was to evaluate the influence of different gene proportions of the Hanoverian Warmblood Horse and other horse breeds used for crossbreeding on the prevalences of common radiological changes, which are possibly relevant for a long competitive life of horses. The data included 6184 horses which were intended for sale at 67 auctions, organised by the Association of Hanoverian Warmblood Breeders in Verden/Aller in the years 1991 to 2003.



First of all the prevalences of radiographic findings in the limb joints of Hanoverian Warmblood Horses had to be evaluated. Nearly 70% of the examined horses (4228) showed one or more abnormal finding in the limb joints. Single radiographic signs were found in 1116 horses (18.1%), two abnormalities were found in 1350 (21,8%) and three and more in 1762 (28.5%) Warmblood Horses. Orthopedic changes were more prevalent in male than in female horses. The most frequently found alteration was the isolated radiodensity (28.4%/3289) followed by changes of the navicular bone (extended and/or deformed canales sesamoidales: 27,5%/3189) and degenerative joint diseases (22.7%/2630). Similar trends were seen in the extremities and in single limb joints. The forelimbs were more frequently affected in contrast to the pelvic limbs. At the thoracic limbs, changes were most frequently found in the fetlock joints when horses had only one abnormal finding. Otherwise the navicular bone seemed to have the highest prevalence of orthopedic changes. The fetlock joint (27-44.3%) and the hock joint (43.2-52.4%) were the most affected sites in the hind legs. In both, the fore and hind legs, the most common radiographic changes were the isolated radiodensities in the fetlock joints. An equal situation was found in the hock joints, however, the frequency of constricted joint gaps as indicators for degenerative joint diseases increased with the numbers of radiological alterations found per horse. The coffin joints were most frequently affected by signs for deforming arthropathies. Isolated radiodensities and deforming arthropathies had a similar high frequency in the distal interphalangeal joint.



The first communication analyses the influences of the different proportions of genes on the prevalences of isolated radiodensities in the distal and proximal interphalangeal joints, the fetlock and the hock joints and for all localizations. The prevalences of isolated radiodensities of the examined horses were as follows: 4.2% (258) in the distal interphalangeal joints, 1.1% (65) in the proximal interphalangeal joints, 22.5% (1391) in the fetlock and 9.6% (596) in the hock joints. Horses with at least one alteration in one or more of the examined localizations had a percentage of 33.6% (2075). The proportion of Hanoverian Warmblood genes was significant for the prevalence of isolated radiodensities in hock joints and all localizations of limbs examined. Horses with a gene proportion of 50.5 to 80.2% of the Hanoverian Warmblood were at a higher risk to develop isolated radiodensities. The occurrence of isolated radiodensities in the proximal interphalangeal joints was significantly influenced by Trakehner incrossings. Significant differences between single classes of gene proportion were additionally found for Arabians and the Hanoverian Warmblood in fetlock joints, for the Trakehner horse in hock joints and other breeds in all examined limb joints. Isolated radiodensities were more prevalent in male than in female horses. Four years old horses showed the highest prevalences.



The aim of the second communication was to analyse the prevalence of degenerative joint diseases with respect to the influence of different gene proportions of the concerned horse breeds on in different limb joints. In the distal interphalangeal joints the prevalences were estimated as 6.2% (383) and 3.1% (194) in the proximal interphalangeal joints. The frequency for the fetlock joints was 2.8% (175). The most affected localizations were the hock joints with 12.7% (786). If horses had a minimum of one affected joint, the prevalence was 22% (1359). For the distal interphalangeal joints a significant effect was found for the Holsteiner Warmblood Horse and the Hanoverian Warmblood Horse. An increasing proportion of each breed leads to a higher prevalence of degenerative joint diseases. The occurrence of alterations in the proximal interphalangeal joint was influenced by the gene proportion of the Trakehner and also the Holsteiner Warmblood. In this localization an increasing gene proportion was related with lower frequencies of deforming arthropathies in these joints. The prevalences of degenerative joint diseases in the hock joint were significantly affected by gene proportions of the Hanoverian Warmblood Horse. The prevalences were highest with a proportion of 50.5 to 60.4% Hanoverian Warmblood genes. For all joints examined, a significant influence was found for the Holsteiner Warmblood. Deforming arthropathies were most prevalent in the hock joints for each gene proportion of this breed. The English Thoroughbred and the Arabians showed no significant influence on the prevalence of degenerative joint diseases. The male horses as well as the five and more than five years old horses had the highest prevalence for the examined alterations.



At last, significant effects of the different gene proportions on the prevalence of changes in the navicular bone and ossification of the collateral cartilages was studied. A total of 27.2% (1684) of the examined horses had changes in the distal sesamoid bone. Minimal alterations were found in 19.8% (1304) and moderate in 4.7% (289). Severe findings were evaluated in 1.7% (106) of the horses. Gene proportions of the Holstein Warmblood were significantly related with changes in the navicular bone. Most frequently, horses with a gene proportion of the Holstein Warmblood breed between 10.4 and 15.6% were affected by alterations of the navicular bone. In addition, an increasing proportion of genes of the Hanoverian Warmblood was associated with a higher frequency of affected navicular bones. Significant influences on the prevalence of collateral cartilage ossification were proved for the gene proportion of the Holstein Warmblood. In contrast to the situation found for the Holstein Warmblood, an increasing percentage of genes of the English Thoroughbred, the Hanoverian Warmblood and the Trakehner led to a lower prevalence of ossification of the cartilage of the third phalanx.

It's rather confusing to me.

[Oakstable]

Seems to be saying that "issues" in radiographs are quite common in Hanoverians and Holsteiners. Wonder if this finding is because of the growing use of digital machines?

Digital can pick up something as small as a grain of rice.

Would be worth knowing the impact on usefulness.

I posted a thread on a Belgian Grand Prix jumper being approved by the KWPN. He has an OCD in his knee on the right hind. He also has offspring competing.

The Trakehner is basically an Anglo-Arab. Arabs are known for hardiness. Though one of my Arabian breeder friends had a colt with big OCDs in the stifles. This colt tried to jump a fence and ended up being hung up on the fence, teetering on his stifles. So ... injury related.

[BeastieSlave]

Hmmm, that's interesting. I think I'll have to come back and read it a few times to let things sink in.
I'd also be interested to know if any of the "issues" are really just the types of things that have been there all along and are being revealed more often by improved technology.

I had a HAN mare with a navicular cyst. The vet at Rood & Riddle said (in 2003) that a high percentage of the WB's he saw (25% IIRC) had them, and of those, 75% were never bothered by them....
FWIW, that mare was 50% TB.

[alexandra]

Sorry but already a short page with some stallion notes takes me half an hour to tranlsate so what should motivate me to translate this difficult scientific german (evgen harder ?) and publish ist online ? One could write to the original person writing it or the Verband and ask if this would be worthwile and financed by someone to be transalted. Alone reading these 120 pages of doctor thesis is quite difficult...

The name of the author by the way sounds familiar. But just am not sure.

[Kareen]

The general problem I have with this study is that it leads to the miscomprehension that incidence of 'radiological findings' corellates with any kind of unsoundness which is to date at least unclear. While everybody knows that OCD lesions and other 'findings' may lead to clinical problems I have failed to find any studies indicating how many of the affected animals in fact turned into clinical cases and whether or not clinicians are safe with the 'assumed incidences' of clinical problems as outlined in the radiological guidelines.

I have written to the Hanoverian Verband two years ago suggesting to find a way to create a soundness index because in my experience being able to produce a sounder horse bears a unique advantage for breeders to market their product. Over the last couple of years the safety-awareness and security precautions of humans have drastically increased in nearly all areas of our lives as far as industrialized nations are concerned. E.g. 20 years ago nearly nobody in Germany would have thought of PPE x-rays on a clinically sound horse in an attempt to rule out a 'problem in waiting' down the road. Likewise nearly nobody would wear a helmet to ride a bike... Nowadays it has become custom to often spend more $$ on much on PPE x-rays than a horse's overall veterinary expenses should be in any given year (again my way of thinking... - trying to create perfect world scenarios...)

This need for security I think needs to be addressed with a soundness index that can be related to a breeding animal much like a dressage or jumping index. But it needs to bear truely relevant data (as in a total picture of soundness which is much more than the question of which x-ray class the horse ranks in).
If any data relating certain x-ray findings to specific clinical problems is available it is all about racehorses which are exposed to a whole different range of problems than sporthorses.

Besides the highest prevalence of career-ending or fatal health issues in the horse (as far as indicated by insurance company data) are still soft tissue problems followed by gastro-intestinal problems and circulatory/respiratory diseases. Reducing equine soundness to the process of spotting x-ray findings (or lack thereof) therefor creates a false approach.

I would want for a soundness index that could be created by a few very simple parameters. Of course there are environmental factors such as upbringing, management and a rider/owner but so there are with x-ray findings which are known to be mostly multifactorial.

In my way of thinking we should look at overall fertility, total lifespan and duration of use first before even thinking of putting the stigma of 'bad x-rays' onto any stallion, broodmare or bloodline.
While it is near impossible to look at all factors and medical conditions leading to premature death, loss of use or premature end of showing careers, I find the results are what interest us and the buyers. I don't care what kind of x-ray finding my old showhorse had and I'll never know because he was never x-rayed although we showed extensively together over 10 years total and he had a useful life as a schoolmaster for five more years with the lady who bought him when I picked up school.

Likewise I think once a true 'soundness breed value' is established buyers have a much better tool to make an educated buying decision than with the current 'crystal ball veterinary' approach which again and again proves itself pointless as it expects veterinarians to predict the future which they can't.
It would also create a motivation for breeders to set their focus on soundness as a goal in their programme.
Today the soundness-goal is limited to prducing a youngster with 'pretty, saleable' x-rays which bears little prognostic value - if any.

Poor fertility, short overall lifespan and limited 'half life' in performance are parts of the big picture I want to look at. These are factors that will affect breeders and future owners much the same. I therefor think it would make a lot of sense to incorporate these into a soundness index. The effort to collect this extra data seems marginal compared to the huge marketing advantage to be expected from creating a reliable soundness index.
And at the end of the day if it leads to improving the overall soundness of the breed it will serve the individual horse a lot because it should significantly reduce down-time, confinement-time and those tragic cases of premature loss of use every breeder wants to reduce if they can.

At this point we are still missing the tools. Not all breeders can look back over generations. Especially not with the structural change away from the 'once and forever' type breeder with a farming background and often maintaining the same female family for a row of generations.
What with all the programmes who have been founded only a few years ago. Right now without the relevant information on file these are at a loss compared to those who have bred for decades (sometimes more than a century) and large numbers and can go back to their own observations.

[vineyridge]

Thanks, Kareen and Alexandra, for responding.

As Kareen says, the next step is correlating the radiograph findings to actual soundness and also to the percentage of hot breed genes in foals that would lead to the "best" bones. That would truly be useful to buyers and breeders alike.

But as a lover of hot blood horses, to me the study indicates that the admixture of their genes improves radiographs in young German horses sold at the elite auctions.

Of course, I could well be reading the abstract incorrectly. :)

[ne1]

in holstein it has long been desired to get the right tb blood into the pedigree, and there is much discussion there on the ground as well as on the internet about it. never once in any of those discussions in which i have seen or in which i have been involved has any reference whatsoever been made correlating the need for appropriate, well-placed tb blood in the pedigree with the incidence - or lack of - of ocd.

[anglotrak]

Since when is a Trakehner basically an Anglo-Arab??!! The influence is there, but mostly not up close. There are a few exceptions, but they will be Anglo-Trak or Arab-Trak for the most part.

[Oakstable]

The research was published six years ago. Surely it has been discussed by vets in Germany?

[Kareen]

Not quite. Interestingly they found all kinds of relations much depending on the individual finding. I've always been a bit weary about studies with this kind of preselected material. Afterall by looking at auction horses only we're looking at a positive-selection.
One thing I wonder is what may have happened 1996/97 as there are a variety of findings that showed a tremendous increase all beginning that year...
And then what about pre-auction surgical prodecures. The work nowhere mentions if and how many of those horses had undergone arthroscopic surgery prior to being selected. It would be interesting to know what happened to those and if all surgeries were disclosed by the owners and/or if they were even aware of them.
In order to truly make any relevant statement about significance I think one needs to look at non-preselected material as clearly this study ruled out by design: All horses that turned up with clinical problems before riding age, all horses that died or were destroyed before riding age and all horses that did not meet the quality-standard to get accepted into the auctions to begin with.
What if typiness or good rideability were a main factor and corellated to any of the evaluated findings in any way?
The section about navicular changes clearly reveales a major weakness in the design namely that horses with severe faults in lower digital conformation (hooves!) were ruled out to begin with. How can you assume a relevant statement about navicular changes when you rule out a factor known to significantly increase the prevalence of navicular changes...
This work must have been an awful lot of labor and Kudos to the lady for all her hard work.

I somehow get the impression the design was layed out to prove or demonstrage a suspected point (namely that Holsteiner blood influx would negatively impact the quality of radiographs in these horses). The conclusion drawn in the summary to be cautious with infusing Holsteiner genes into the Hanoverian seems quite a bit off base when in detail it looks as if overall little corellation can be found between genetic composition and radiograph-quality.
The significance only showed in a few locations and changes and what good is in knowing that coffinbone-cartiledge-ossification (colloquial 'sidebone') may be increased with horses that have a higher percentage of Holsteiner genes when this particular finding only affected a total of 3.2% and thus seems to be not too much of a concern altogether?

Also the corellations were seldom linear but the prevalence was mostly altered only in the middle range (e.g. horses with 10.41-15.46% Holsteiner genes were most likely to show 'sidebone' whereas horses with an even higher percentage were affected less frequent than the previous group. If there is no linear corellation I don't think the conclusion (read: Watch the Holsteiner influx) is quite fair.

To me the biggest revelations and questions I would be interested in learning more about are:

-what happened in 1996/97 because from there on we see a highly significant increase in mild (class I) navicular changes, sidebone, mild (class I) Hock changes, coffin joint, ankle and fetlock changes plus OCD lesions in hocks and coffin joints?!?!

-why seem male horses more prone to many of the evaluated changes than females (except fetlock OCD lesions and sidebone)?

-if preselected horses are chosen as 'material' for a comparative study shouldn't it be a negative preselection (looking at worst case scenarios) because avoiding these is what interests most breeders and owners? It doesn't seem quite fair either to compare any of the prevalences found in this study working on preselected horses to other (random) breed studies where the material was not preselected at all (e.g.Icelandics study had both random studies plus clinical studies on manifest lameness cases; Dutch stallions in the study mentioned are subject to serious preselection by virtue of licensing x-ray procedures whereas mares were mostly unpreselected)).

[Kareen]

To arabtrak: Where does it say that about Traks? They looked at Trak genes separately and Arabs separately?
I do remember some discussion about the study but it was more in horse-breeder circles than veterinary as it originated in the breeding-science department of Hanover vet school, not the equine hospital department.

It didn't say anywhere how in detail they determined the genetic origin (e.g. how far back did they look within the different breeds as Traks have a significant percentage of both TB, Arabian and other breeds while Holsteiners have significant TB percentages within them). Did they just go back and look at the first Holsteiner branded stud showing in a pedigree and count him as 100% Holsteiner or did they in fact look in the generations back?

They also didn't look at the horses that didn't pass the clinical. Why? Afterall if a horse is lame and has x-ray findings on top those seem to bear more relevance than x-ray findings on their own without any lameness to go with it...