Study Shows Total Rest May Increase Odds Of Breakdown In At-Risk Racehorses

by | 02.12.2018 | 7:27am

Joint surface collapse in horses is a degenerative condition that can result from stress fractures (also called bone fatigue) from repeated loading of the legs. While many trainers rest horses suffering from bone fatigue, a complete stop of exercise may not be the answer—in fact, it can even exacerbate the chance of catastrophic breakdown, reports HorseTalk.

Researchers at the University of Melbourne studied joint surface collapse in horses with palmar osteochondral disease, which affects the lower leg bones. The study examined whether bone resorption could be correlated with reduced physical activity and contributed to surface collapse in horses affected with the disease, they reported in the Equine Veterinary Journal.

The team used metacarpal bones from 36 deceased Thoroughbred racehorses, 29 of which were in training at the time of their death. Their bones were examined via CT scanner and electron microscope to see if joint surfaces had collapsed, and whether bone surfaces had eroded or become porous.

Horses that were resting had higher porosity and surface erosion of the bone; in some resting horses, there was an apparent loss of support for the calcified cartilage layer. The researchers noted that collapse of joint surfaces was common in cases of palmar osteochondral disease and likely resulted from stress fractures, which have been shown to contribute to fatality risk.

This study may support assertions from practicing veterinary surgeons that a limited workload, as opposed to complete rest, may be the better option when managing a horse with stress fractures.

Read more at HorseTalk.


  • Amen to keeping a thoroughbred fit by regular work! Too many modern trainers think stall rest is the only way to heal or keep a horse sharp. Far from the truth. The Maryland shin study pretty much says the same thing, the right kind of training that stresses the bones just enough is the very best way to prevent bucked shins and as far as I am concerned, most all racing related osteo-pathology.

  • 33horses

    Osteon by Platinum Performance is a really good supplement for bone strength also

    • NMBird

      Is that the same company that makes Platinum formulas for dogs? My dogs took Platinum …it was chock full of stuff that my integrative recommeds for my own supplementation, including alpha lipoic acid!

  • Dadnatron

    This is the problem with research and making protocol based upon a single study. Also, in taking ‘advice’ from researchers in their ‘thoughts about the issue’. Both of these articles are by the same authors using the same horse specimen and looking at the very same part of the horse.

    Study Suggests Race Training Too Hard For Equine Legs (1/26/18 Horsetalk) More recent study published 10/2017.

    “Rest from race training may allow some degree of repair in the microscopic damage, they said. However, the burden of damage in this population suggested that, in general, the horses might need more time off from intense training than is currently the case to minimise the risk of bone injury.”

    Subchondral bone pathology occurs with a high prevalence in Thoroughbred racehorses presented for postmortem examination. The accumulation of subchondral bone damage with longer career duration is consistent with bone fatigue.

    And here is the quote from the SAME authors using the SAME horses and specimens from The article written about today.

    Complete rest may increase the risk of joint collapse in at-risk racehorses – study (2/6/2018 Horsetalk) This study is actually older being published in 3/2016 in Equine Vet

    “They concluded that although collapse of the joint surface may occur while a horse with palmar osteochondral disease continued in race training, the faster bone resorption seen during rest was likely to make the problem worse.”

    This is the author’s abstract conclusion:
    Articular surface collapse is common in cases of palmar osteochondral disease and is likely to be a sequel to fatigue injury of subchondral bone. Focal subchondral bone resorption appears to contribute to collapse of the calcified cartilage and is potentiated by a reduced-intensity exercise regimen.

    I purchased the initial study and basically it stated, that in its finding, the risk was significantly ameliorated with 1-2mo out of racing. On the surface, the ‘current’ article appears to say the exact opposite. I’m not wasting my money buying this article…

  • NMBird

    Well, speaking as a human who suffered stress fractures in both feet this past year, I can say that at some point after the initial healing period in a boot, the next step…and it was a matter of a few weeks…was to start putting some weight on the foot to encourage bone growth and strengthening.

    It made me nervous because I thought I’d break something again, but it all turned out OK. I can only imagine how hard it is to judge what is too little, enough, or too much too soon with a horse!!

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