Beasts of burden
How much weight should a horse or pony carry? In an exclusive for Equine magazine, British Horse Society Regional Manager for the North of England, Wendy Suddes explores the current facts and outlines the main considerations in this much-discussed issue.
Equine anatomy and physiology studies universally agree that from the point of view of vertebral construction the equine spine, with its suspension bridge-like construction is essentially, very poorly designed for carrying weight. Contrary to this, camels and cattle, equipped with interlocking lumbar-spine articulations, are in theory, capable of bearing substantial loads. Sadly however they do not possess the remarkable athletic ability, (and ride-ability), found in horses and with limited talent for collection and jumping, they are simply not as much fun to ride.
A much more appropriate role for the horse is to pull weight in harness. Without the pressure from above, horses are able to round their top line and engage strong muscles in their hindquarters. It is widely accepted that pulling weight also presents a low risk of damage to even immature musculoskeletal systems in the horse.
Research does however suggest that pushing immature (pre five year old) horses into work under saddle (and rider) can give rise to a number of weight-bearing related injuries and conditions, which can ultimately compromise welfare and soundness.
Whether pulling or carrying weight, the important questions remain: how much weight is appropriate and how much is too much?
How much weight can a horse actually carry?
In competition, weight has been used for centuries, as a handicap, to put better class horses at a disadvantage over less able ones – a practice that can significantly affect the outcome of a race.
The key problem however, lies in the fact that each horse has an individual weight limit - beyond which, the ability to perform to optimum natural ability will cease and breakdown becomes likely. Unfortunately, we currently have no way of determining that limit without testing the individual horse.
The weight-carrying ability of individuals depends on a number of physical characteristics and external limiting factors, including but not restricted to:
• Conformation
• Size
• Body condition
• Age
• Clinical (or Sub-clinical) injury or disease
• Ground conditions and terrain
• Duration of the work to be done
• The speed at which the horse is expected to travel
• The skill and balance of the rider
Historically - but in the absence of any scientific evidence - it has been widely believed that the bigger and heavier the horse, the more weight it is capable of carrying and that certain breeds have developed to carry heavy weights more ably than others. There is unfortunately a critical lack of scientific evidence on this subject and some of the few studies conducted undoubtedly have flaws. Whilst we await the result of research (some of which is currently underway), riders MUST give the utmost consideration to how excess weight can affect the welfare of the horse.
Calculation of precise weight-bearing capability is unlikely to ever be an exact science, not least because individual strength, condition and the willingness to please inherent in most horses, serves only to complicate the issue. In time perhaps, research will permit parameters to become available for certain breeds and types – with necessary adjustments made for the range of limiting factors mentioned above.
Conformation Analysis accepts that the primary requirement of a riding horse is to bear a rider's weight on the free-span of the back without strain. Certain conformational qualities can make that weight easier for the animal to bear. These qualities include:
• Strong loins (the part of the back behind the saddle) - broad, short, smooth and strong. The circumference of the horse around the loin and groin should be about the same as the heart-girth circumference
• A short to medium-length back
• A neck that is set high on the shoulder, with a shallow curve at the base of the neck
• Moderately high withers, with a peak that lies well behind the horse's elbows
• A pelvis that constitutes at least 30% of the body length and slopes from 18-22 degrees
There is evidence from the USA to suggest that weight-carrying ability, is mainly a function of body breadth (especially over the top of the loins), rather than a function of height. Interestingly, it is proposed that few tall horses (over 16hh) are broad enough, whilst simultaneously staying within the ideal weight limit for their limbs. Remarkably, the potential for continued soundness has been deemed compromised, once weight exceeds 658 kg. This is admittedly an unusual figure - but close to the weight of many horses over 16hh, before a rider climbs on board. Those who have always believed big horses are capable of carrying higher weights should perhaps take note - as any further weight is only considered acceptable, provided the adult animal is never expected to work at suspended gaits (ie is working in walk only).
Herein lies the problem (and the main reason rider weight is currently in the news), because suspension is of course, a necessary quality in the vast majority of riding horses, as they are expected to trot, canter and jump.
A case in point might be that of Highland ponies - historically the breed developed to carry stags from mountain sides in walk only, whilst kept specifically fit for purpose, lean and muscular.
Today, native breeds like Highlands are usually maintained with a body condition score greater than 3 (or 5, depending on which scale is used), are regularly confined to stables or small paddocks for long periods, often ridden infrequently in faster paces than walk – and additionally, often expected to carry riders who would be considered over-weight (or even obese). The odds for long-term soundness and well-being are therefore sadly stacked against them.
Consider this: In humans, there is a proven link between carrying excess weight and leading an inactive lifestyle and the onset of back, joint and muscle pain. We certainly would not expect these individuals to be able to perform to the best of their physical ability – let alone carry an additional load.
Fortunately for the vast majority of our equine friends, humans have all sorts of uses for horses and ponies - not all of which requiring superior weight-carrying ability. A skillful, knowledgeable, well-balanced rider, who gives full consideration to the welfare and physical limitations of their horse, would surely never seek to test the maximum weight-carrying ability of their mount?
Most recent studies have concluded that a horse or pony should not be regularly required to carry more than:
• 10% of ideal bodyweight if performing at extremely high intensity (elite competition) or
• 15% of ideal bodyweight, in other circumstances
These figures are not inclusive of tack and further allowances may need to be made if the horse is required to carry unusually heavy equipment. It is also vital that these calculations are based on ideal rather than actual bodyweight of the horse – so accurate condition scoring is an important aid in assessment.
A horse that is significantly overweight will not be sufficiently fit to carry 15% of its (obese) bodyweight. Equally, a horse that is significantly underweight should not be ridden at all.
Perhaps, whilst we await the results of ongoing research, we don’t need scientists – just some honest friends and a little self-awareness, to tell us we need to beat the bulge for our horse’s sake.
This article first appeared in the Jan-Feb issue of Equine magazine. Annual subscription cost is just £20 for 11 issues; to subscribe securely online, visit The Equine Store
