The recent ‘measuring out’ of the 2009 Horse of the Year Show small hunter champion Unlimited has once again brought the matter to the attention of those that write headlines and fill the columns of equestrian publications. Last year renowned showing producer Lynn Russell ignited debate over the mid-season measuring of horses by refusing to have lightweight cob Deimos re-measured following the lodging of an objection to his height by Ponies (UK). The reputation of the UK’s height scheme took a further battering with alleged measuring anomalies centred on an Essex vet. At the core of the measuring controversies are two unmistakable facts. First, measurements of horses and ponies at the withers are susceptible to wide variation and influences. Second, there can be significant financial benefit from an animal being under a certain height and thus qualifying for specific sections or classes. Well over 100 years ago Wortley Axe defined a horse’s height as “the vertical distance from the highest point of the withers to the surface on which it stands”. This still remains the basis for measurements and, despite advances in technology, we continue to use a wooden stick with a horizontal arm to perform the measurement. Height certificates are issued by the Joint Measurement Board (JMB) in the UK, who employs a panel of official measurers who are all vets. Annual certificates are given to animals aged four years and above, and full or life certificates are issued to animals once they are at least seven years of age. The JMB produces detailed guidelines on the preparation of animals for measurement and the measurement procedure itself. Measuring sticks must have a metal ‘shoe’, a spirit level within the horizontal arm, and be calibrated every four years by weights and measures or Trading Standards. All measurements are carried out on ‘pads’ that have been inspected by the JMB to ensure that they are level. Concerns that using measuring sticks maybe an inaccurate means of measuring horses have been proven to be invalid. Research comparing traditional sticks with laser devices has consistently shown good agreement between the two techniques, in terms of both the absolute measurements and their repeatability or consistency. Some caution might, however, be warranted in respect of the fact that the JMB’s guidelines only require calibration of sticks every four years, which is a long time in the life of equipment in a veterinary practice. Also, and to the best of my knowledge, the calibration process only checks the accuracy of the vertical component of the stick and not the horizontal arm with its integral spirit level. These concerns aside, it is not the measurement device that is the greatest source of variation. Rather it is the inescapable fact that there is no rigid anatomical connection between the withers and the feet that touch the ground. The horse’s spine, with the processes that form the withers, is actually suspended between the forelimbs by tendons and ligaments. Alterations in the tone of these soft tissues, as well as the muscles with which they connect, can cause the chest and spine to sink or rise. For instance, simply allowing an excited pony to stand and relaxed can, in my experience, cause the height to drop by as much as 6cm. Measurements are taken without shoes and simply trimming the heels and leaving the toes long can reduce height by more than cm. Measurers have the right to refuse to measure an animal that is presented with feet that have been trimmed excessively. There have been several scientific studies of factors that might alter the tone in the soft attachments between the limbs and trunk and influence hence the height of horses and ponies. Positioning of the horse, transport, exercise and sedation have all been examined, along with variations for individual measurers from day to day and between different measurers. Lowering the head to the ground can significantly reduce the height at the withers – by nearly 2cm – whereas raising the head can increase height by over 2cm. The JMB specify that, during measurement, the head should be in a ‘natural’ position with the eyes no more than 8cm above or below the highest point of the withers. Even within these narrow limits, height can be increased or decreased by over 0.75cm. Transport, contrary to popular belief, appears to have little effect on height measurement albeit when relatively short journey times have been studied. It is possible that longer periods of travel, with associated restriction of access to food and water, might be more influential. The effects of exercise on height appear complex. There are anecdotal reports that working a horse or pony prior to measurement can reduce its height but this has not been borne out by research. Many producers believe that horses in work or in show condition are taller than when they are ‘let down’ at the end of the season. This has been behind much of the frustration associated with horses being recalled for measurement mid-season. Sedation or administration of tranquilisers can have a very substantial impact on height, reducing it by nearly 3cm. Animals presented for measurement should not be in receipt of any prohibited substance and measurers can either refuse to measure an animal that they suspect has been ‘doped’ or take samples for subsequent analysis . Finally, repeated measurements taken of a single animal by the same person can vary by as much as 1cm, whereas differences between two different measurers can amount to nearly 2cm. A final factor that is critical to a horse or pony’s measured height is its ability to relax in the environment where the measurement takes place and be comfortable in the presence of a stranger with a potentially scary measuring stick! Never is this highlighted better than at the FEI’s European Pony Championships. In 2007 the FEI moved away from a system of height certificates for internationally ponies to one where they are actually measured in competition. Ponies are measured shod, with a 1cm tolerance allowed for their shoes, and a further 2cm tolerance for the fact that they are being measured in the middle of the season at a competition venue. This means the height limit is 151cm. I was ‘fortunate’ to be one of the two vets that did the first measurements at the 2007 Championships in Freudenberg, Germany and have done them each year since, including at the recent Championships at Bishop Burton College. On each occasion we have measured over 150 ponies in a single day. What is amazing about many of the championship ponies is just how relaxed they are around a measuring stick. I distinctly remember, in the line of ponies waiting to be measured at Avenches, Switzerland in 2008, a grey horse that looked at least 15.2hh. Fearful of creating an international incident I anxiously awaited its arrival at my station. It settled into the stable and when I put the stick onto its withers the horizontal bar read over 156cm. But the withers instantly started to shrink under the bar – as if contact with the stick had triggered a reflex – and kept sinking until, within a couple of minutes, the pony measured 151.5cm. Many of the ponies at this year’s championships showed similar reactions, no doubt the results of months of training at home. Why go to all that effort? Putting it bluntly, a European team pony might be worth several hundred thousand Euros, whereas a pony that won’t measure 151cm is practically worthless. My experiences aside there is undoubtedly a need to improve the validity of height measurements and their perception within the equestrian community. So, how might this be done? As a start, I would advocate that, if vets are to continue as measurers, then they should not be asked to perform measurements for clients of their own practice. While I am not suggesting that this may be a source of favour, it does create a conflict of interest. It could be very difficult to tell a valuable client that their horse or pony has measured out by a small margin. Perhaps the JMB or its constituent member societies could look at the FEI’s model of in-competition measuring. Alternatively, all ponies and horses could be presented to regional testing centres, staffed by stewards of the JMB, in say January and July for measurement. This would remove the accusation that some horse and ponies have travelled to certain vets that might be considered to be ‘kinder’ in their measurements. Finally, I would suggest that all animals being measured have a blood sample taken – as happens with pre-purchase examinations – so that there is a real deterrent to the use of prohibited substances.