How do you feel when you get up in the morning? Do you bounce out of bed, or does it take you halfway to the bathroom to lever yourself upright? The answer will depend chiefly on how old you are, but also on what you did the day before, your level of fitness and even how comfortable your bed is.
Horses aren’t that different from us when it comes to early-morning stiffness. As autumn arrives we bring them in from the field, shut them in a stable for 14 hours each night and then wonder why they pull out the next morning less than supple.
The stiffness we see in horses comes from both the muscles and joints, but the underlying cause of each is subtly different. Joint stiffness is more age-related, the result of wear and tear. This occurs first as thinning and then loss of the articular cartilage, the smooth covering to the ends of bones that allows joints to move easily. There can also be thickening of the ligaments, and eventually new bone laid down around the joint. The result is inflammation within the joint and a reduced range of movement.
Joint stiffness will be made worse by hard work, firm ground or cold weather, because these are extra stresses on top of underlying damage. Joints stiffen overnight because when they are not moving, the synovial fluid — the oil that lubricates them — soaks into the cartilage. As the horse starts moving again, fluid is released and the joint loosens up again.
Muscle stiffness is more directly a result of recent exercise than of increasing age. The theory that stiffness and pain are a result of lactic acid build-up in the muscles has now been largely disproved. Lactic acid (or more correctly, lactate), is the probable cause of the muscle fatigue and pain felt during bursts of very intense exercise, but the general stiffness and soreness felt the day after hard exercise is due to low-grade damage to the muscle fibres.
The medical term for this is delayed onset muscle stiffness (DOMS) and it is the result of trauma to the membrane around muscle cells, which allows chemicals to leak out and trigger pain receptors. When a horse stands for long periods after exercise, the damaged muscle fibres contract and the muscles become stiff.
There are more serious causes of muscle stiffness, such as tying-up — when the muscles over the quarters cramp up during exercise. Some horses are more susceptible, and the trigger is often exercise following a period of box rest.
Movement is medicine
While some horses go out for part of each day in winter, many only leave the stable for exercise.
For older horses and those in full work, prolonged stabling is a recipe for stiffness. Some common-sense steps can help keep this to a minimum. The most obvious requirement is a stable large enough for the horse to move about freely, with plenty of dry bedding to encourage lying down. There should be good ventilation, without draughts, and the horse needs to be kept sufficiently warm.
If you can turn out during the day then do. For those with plenty of dry, well-draining turnout, remember that older horses can do better when out full-time, provided they are well rugged and have access to shelter.
The best way of managing stiffness is by regular, controlled exercise. All exercise should start with a slow warm-up and end with a period of cooling down. Begin your warm-up in walk, with the horse in a relaxed frame that allows him to stretch down. Then ask for gentle flexion and do large circles, before moving into trot.
Some people like to do stretches with their horse before mounting, but a ridden warm-up is simpler and uses all the muscles in their natural range of action. The length of time needed for warm-up and cool-down varies, but each should be at least 10 minutes. Muscles need to be kept warm, so for clipped horses an exercise blanket can be helpful.
Treatment options
Massage and physiotherapy have a role, but these are usually one-offs and not a substitute for a sensible daily routine. The same is true of spas and laser treatments.
Massage rugs have grown in popularity, although how much actual massaging their gentle vibration can achieve is debatable. Nonetheless, horses seem to find them relaxing and they may keep muscles warm. Magnetic rugs will do the same, although that is all they will do. Repeated studies in humans have found such magnets to have no beneficial effect — and there is no valid scientific reason why they should.
For stiff joints, there are fewer treatment options. Joint supplements have some value but their effectiveness is probably limited. The most important ingredient in a supplement is glucosamine, which should be fed at a level of 10g per 500kg horse per day. MSM is probably helpful as well, as are vitamins A, C and E.
Devil’s claw is a plant extract available in a number of herbal products. Trials have shown that it can reduce joint inflammation, and for this reason it has been added to the FEI list of controlled substances. It is not as powerful as phenylbutazone (bute), however, and some older horses reach the stage where a daily dose of bute is necessary to keep them comfortable. Bute comes from the same family of drugs as aspirin and ibuprofen. It is safe even long term, if given at the correct level, and is very effective at reducing pain and inflammation. A comfortable horse will move more readily and so stiffen up less.
The most important message is that too much rest allows everything to “rust up”. The key to combating stiffness is to keep moving.
Ref Horse & Hound; 21 September 2017
