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Facing up to the challenges of training

by
01 August 2011, at 1:00am

Dr COLIN ROBERTS reports on the summer scientific meeting of the Association of Racecourse Veterinary Surgeons which looked at numerous topics of welfare significance

MEETINGS of the Association of Racecourse Veterinary Surgeons (ARVS) rarely fail to be both interesting and practical. 

The association’s yearly Casualty Management Seminar, held at different racecourses around the UK each November or December, is obligatory CPD for racecourse veterinarians and the organisation’s other meetings are generally notable for their interesting speakers and important topics. 

This year’s Summer Scientific Meeting and AGM were held at Chester Racecourse. 

With the sport of racing, like other equestrian disciplines, coming ever-increasingly under critical surveillance by both public and media, the meeting included timely discussions on a number of subjects of considerable welfare significance and space only permits me to summarise a small part of the interesting and wide-ranging discussions that took place. 

Four papers 

Professor Wayne McIlwraith of Colorado State University has for long been one of the world’s leading authorities on orthopaedic disorders of horses and he performed a real tour de force in giving four papers on areas ranging from dealing with the media to intra-articular therapy. 

In discussing the latter, he highlighted its importance by pointing out that it has been stated that 60% of lameness problems in sport horses are related to osteoarthritis. 

The aim of therapy in traumatic joint problems is to return the joint to normal rapidly, if possible, and to prevent or reduce the severity of osteoarthritis. 

Corticosteroids are frequently used for intra-articular therapy and whilst it has been stated that they can have detrimental effects on joint health, Professor McIlwraith asserted that these have been overplayed. 

He pointed out that there are variations in effect between different agents so that although, for example, methylprednisolone acetate has been demonstrated to cause articular degeneration, there is evidence that triamcinolone acetonide is chondroprotective. 

There has been much discussion in recent years concerning corticosteroidinduced laminitis with triamcinolone being perceived as the agent in this group of drugs most likely to cause it. Many clinicians, however, are now comfortable with the use of a total dose of up to 40mg of triamcinolone intraarticularly and in a series of 2,000 cases in which corticosteroid doses of up to 45mg were used by this route, there were reported to be only three cases of laminitis (Bathe, 2007). 

Other agents that can be beneficial for intraarticular use in the horse include hyaluronan and polysulphated glycosaminoglycan, both of which may be considered to be disease-modifying osteoarthritic drugs, whilst more recently introduced agents for the treatment of joints include anticytokine therapy via either autologous conditioned serum or gene therapy, as well as the use of stem cells. 

In a fascinating presentation, Dr Tim Parkin of the University of Glasgow summarised some recent work into the effects of race training as he considered at what age such training should commence, how much should a horse train per week and what are the best surfaces on which to work. 

Contrary to a frequently advanced view that the training of racehorses at two years of age is detrimental, there is now evidence to suggest that horses that train and race at that age are less likely to suffer racecourse fatalities and some other injuries than animals that start their racing careers later. 

Increased risk 

In fact, regardless of what age horses begin to race, the first year in training represents a period of increased risk of sustaining a catastrophic limb failure, suggesting that horses should be eased in to fast work relatively slowly. 

Professor McIlwraith also discussed the effects of early training on horses. Whilst bone and muscle retain their ability to respond to exercise in adult life, some tendons at least appear not to show such adaptability in the mature horse. 

It has been suggested that an appropriate level of exercise in young animals may confer advantages in terms of improved tendon development and early race training has been demonstrated to be associated with an increase in mean cross sectional area of the superficial digital tendon compared with untrained horses. Professor McIlwraith described a multi-centre collaborative study based in New Zealand in which the effects of exercise in thoroughbred horses during the first 18 months of life were investigated (Rogers et al., 2008). 

One group of young horses was kept at pasture with no additional exercise, whilst another also lived at pasture but was subjected to an exercise protocol of gradually increasing intensity, amounting to around a 30% increase in workload for the latter group. 

This extra exercise had no damaging effects and there was evidence of some benefit in terms of development of the musculoskeletal system. 

Degree of conflict 

The volume of work that is optimal for young racehorses is still to some extent uncertain and it appears there is some degree of conflict between the demands of cardiovascular training and the amount of work that increases the risk of injury. 

Excessive amounts of fast work predispose to injury, but horses that have performed no high-speed exercise are also more likely to sustain fatal racecourse injuries. 

A number of studies have shown that between four and seven furlongs of fast work per week is probably the best volume and it is noteworthy that relatively few high load cycles may be necessary to induce a significant adaptatory response. 

Mike Shepherd of the Beaufort Cottage Stables practice in Newmarket has a wide experience of dealing with racehorses and sport horses and he presented some interesting cases that illustrated the value of various imaging modalities for the diagnosis and monitoring of racing injuries and their role in the prevention of re-injury, highlighting the need for good imaging technique and a sound knowledge of the appearance of normal tissues. 

  • Veterinarians interested in membership of the ARVS can contact the secretary via e-mail at secretary@arvs.org.uk. 

References 

Bathe, A.P. (2007) The corticosteroid laminitis story: 3 – The clinician’s viewpoint. Equine Veterinary Journal 39: 12-13. 

Rogers, C. W., Firth, E. C., McIlwraith, C. W., Bameveld, A., Goodship, A. E., Kawcak, C. E., Smith, R. K. and van Weeren, P.R. (2008) Evaluation of a new strategy to modulate skeletal development in thoroughbred performance horses by imposing track-based exercise during growth. Equine Veterinary Journal 40: 111-118.