This issue started out simply - a horse was either lame or not. You can't be a little bit pregnant I was told. As a man this made a lot of sense!

Years down the track and lameness is this big ugly juggernaut. I can only blame vets, ambitious riders and horses, all of which get more complex as they get older.
I have tried to get lameness into perspective as it fits into the endurance picture.

In order that a horse be deemed fit to continue the horse must be judged free from lameness.
The concept of "fit to continue" is the central component of endurance veterinary regulations. It is vital to the future of the sport and the maintenance of equine welfare that this concept remains foremost in our minds. It follows then that the accurate and consistent diagnosis of lameness be a major component in the assessment of horses at endurance rides.

The AERA rules state that "a horse shall be judged to be lame when …it displays at the trot a consistent in-coordination of gait or indication of pain."

The circumstances of the examination are defined for the purposes of consistency and fairness to all competitors in Rule V 3.3.4. The horse is examined in a set pattern and on a standardised surface for each ride. It is inappropriate to trot the horses over uneven ground or on slopes or rocky surfaces.

The rider/strapper must offer the horse for examination in such a way that the horse can display its natural gaits and level of impulsion. It must not be hunted or intimidated. At this point it is worth mentioning that the horse should receive continued training at home so that it will trot correctly in hand under all circumstances. This will avoid repeated requests from the veterinary team for a re-trot. Repeated trot -out attempts are time consuming, fatiguing and unnecessary. To avoid being asked to run again it is important to trot the horse properly the first time.

The level of impulsion is vital in assessing the horse's desire to go forward and reflects on of the many aspects of the metabolic profile of that horse. The loss of elasticity, power and length of stride are proportional to muscle fatigue and often moderately deteriorate over the course. Electrolyte imbalances, dehydration, or any other physiological disease process such as myositis, overheating, or glycogen depletion may adversely affect impulsion.

T.S.Stashak in "Adams' Lameness in Horses" elaborates further: Lameness is an indication of a structural or functional disorder in one or more limbs or the back that is evident while the horse is standing or in movement. Trauma, congenital or acquired anomalies, infection, metabolic disturbances, circulatory and nervous disorders, and any combination of these can cause lameness. The diagnosis of lameness requires a detailed knowledge of anatomy an understanding of kinematics, and an appreciation for geometric design and resultant forces.

With this level of complexity veterinarians are chosen as judges of lameness because of their impartiality, university training and continued work related experience. In addition veterinarians undergo training at courses specifically designed for endurance vetting. The complexity of lameness diagnosis makes for development of skills in the science as well as the art of vetting at rides. It is not then surprising that veterinarians are able to see problems in a horse that lay persons are not.

While it is recognized that many non-veterinarians are very competent horsemen and women, they are not qualified and therefore cannot be recognised as defining or classifying lameness at rides. The opinions of lay people may be worthwhile but they are not valid in the context of an endurance ride. As an example there are many spectators that voice their opinion however there is only one referee and one whistle.

The purpose of the lameness examination is to define whether a horse is to be deemed lame or not at the time of examination. Level of lameness is subject to change depending on recovery or deterioration, both of which may be affected by therapy and time. Ride veterinarians are only able to look at a window into that horses life. If a horse is not lame on track but deemed lame in the vetting area this is not surprising. The effects of cooling down may have a negative effect and bring out a lameness that was "under the surface." In addition the hormones adrenaline and cortisone have analgesic effects and mask lameness in the horse under saddle.

In deeming a horse to be lame no implication is made as to the source of the pain or abnormality nor is any statement made regarding the likely future athletic ability of that horse. It is beyond the scope of the veterinary examination at rides to localise or prognosticate on the lameness. To do so would require further diagnostics, nerve blocks, flexion tests radiographs and ultrasound - inappropriate at competition.

A further "completion" following a vet-out does not imply that the horse was not lame in the first instance, but that the horse is no longer lame. It is indeed fortunate that so many horses only suffer with a brief and minor lameness. Early intervention by repeated veterinary examination saves these horses from the further damage that is inevitably caused by continuation.

Explaining Grading of Lameness:
Complexity exists when we must classify the degree of lameness.
The American Association of Equine practitioners Grading system is as follows:
Grade 0 : lameness is not perceptible under any circumstances.
Grade 1 Lameness is difficult to observe and not consistently apparent regardless of circumstances.
Grade 2 Lameness difficult to observe at walk or trot in a straight line but consistently apparent under some circumstances (eg weight carrying, circling , inclines, hard surfaces)
Grade 3 Lameness consistently observable at a trot under all circumstances
Grade 4 lameness obvious; marked nodding, hitching, and /or shortened stride
Grade 5 Lameness obvious minimal weight bearing in motion or rest inability to move.

If we consider then, the AAEP grading system in the light of vetting the endurance horse:
A Grade 0 horse would clearly pass. The Grade 1 horse would pass at an endurance ride but not a pre purchase examination. A Grade 1 problem is not considered to be a consistent lameness as the pain comes and goes.
The Grade 2 horse demonstrates consistent minor lameness (difficult to observe, depending on the surface) would be signaled for mention as suspect and may perhaps worsen on a second trot and be removed by the veterinarian. On a very soft track the horse would be allowed to continue, as the lameness would not show here. The situation remains fair when all competitors are judged on the same track. Grade 3 , 4, and 5 always removed from competition.

It is the Grade 2 horse, on an imperfect surface, that is usually the most controversial. The gait is difficult to observe and thus may be mistaken by the layman and labled "that's just the way he goes", or "he has a rolling gait." This horse clearly and consistently has a problem but only under certain circumstances. This problem may persist for several rides before it either manifests as overt lameness or is given rest and appropriate treatment by the astute trainer. This horse is in the grey zone.

It is normal practice for the Head Veterinarian of a ride to "set the standard" and to rule a clear line through the grey zone. The vetting team then adheres to this throughout the ride. Thus a horse is either above the line or below. Thus the issue becomes black or white. Discussion between vets is allowed and in many cases encouraged to canvas opinions and educate the less experienced. However the Head Vet has the final opinion to ensure consistency.

In some cases where your horse is borderline it is often difficult to accept your horse has a problem. Remember that the veterinarians will only remove the horse if they believe the gait abnormality will compromise the horse. Hard vetting is considered unnecessarily punitive and not within the spirit of the sport. Soft vetting will only compromise the future of the horse and devalues the completion award.

This seemingly complex issue of lameness evaluation is hopefully thus explained. Ride veterinarians seek only to uphold the rules. Thus we act as referees with an interest in keeping the sport alive with consistency and equality and an undeniable devotion to putting the horse first. If you have any doubt as to the fairness of a decision try wearing horse shoes for a day.

David Brown BVSc MACVSc