Deep or slippery going can put extra strain on the tendons and ligaments of the lower limbs. Gil Riley MRCVS outlines a seasonal survival strategy.
Horses and heavy ground do not always go well together. Having evolved in hot, prairie-like environments, horses are happiest when their feet are planted on firm, dry ground – which is not always possible during the colder, wetter seasons.
Soft going demands more of the horse’s limbs, especially the tendons and ligaments that run down the back of all four lower legs. The heel, which is narrower than the toe, will sink further into the soft surface and over-extend the lower joints in the process.
As a result, both the superficial and deep digital flexor tendon (DDFT), along with the accessory ligament of the DDFT (also known as the check ligament) and the suspensory ligament, are under greatest pressure.
Of the two tendons in the cannon region, the superficial tendon is much more likely to suffer a strain. This is because it is a less robust structure than the DDFT and, lying just under the skin, is more likely to be damaged by a hind limb that may be thrust forward as the horse slips and maybe falls on heavy going.
The DDFT is also supported in the cannon region by the check ligament, which can take the strain if the tendon comes under excessive load. While the check ligament is also a tendinous structure, it usually recovers after around four months of rehabilitation; a tendon repair takes much longer, closer to 12 months.
From the foot to about a third of the way up the cannon, the flexor tendons run within the digital flexor tendon sheath. Mild over-extension can lead to an overproduction of synovial fluid within the sheath, causing puffiness called windgalls.
Should just the sheath be involved, this tends to be limited to a cosmetic blemish – albeit one likely to remain. Sometimes, however, the tendons themselves are affected.
The DDFT lacks the support in the sheath that it has further up in the cannon region and is more likely to sustain damage. In the forelimb, injury to the outside edge of the DDFT is the most common tendon issue within the digital sheath. In the hind limb, the area that typically sustains damage is a piece of tendinous tissue called the manica flexoria, which links the flexor tendons.
Injuries to the tendinous structures within the sheath will not resolve with conservative treatment. Surgery is required to debride (clean) the damaged tissue, before a period of recuperation.
Sticky situations
Heavy going can cause one or more of a horse’s limbs to be forced into an unnatural position. Typically, a foot becomes stuck in the mud, or the horse slips. All manner of injuries can result.
Spinning suddenly while a foot is glued in the mud can mean that the pedal bone turns within the hoof capsule, and the stress exerted can cause the bone to fracture. Provided the fracture does not penetrate the coffin joint, this should fully repair with supportive shoeing and some months of box rest.
Slippery ground can cause a limb to suddenly give way laterally (sideways), leading to strain of the supportive ligaments of the joints. The fetlock, knee and hock are most commonly involved.
Most of these injuries will recover fully with rest, followed by a gradually ascending programme of walking out.
In the case of the hock however, where one of the ligaments forms a boundary of the joint, a surgical tidy up of the damaged ligament is usually required to kickstart recovery.
Doing the splits with the hind limbs can be especially traumatic and may cause rupture of the muscles on the inside of the thigh.
While a horse will usually recover from muscle tears, hip fractures can also occur. Except in miniature ponies, the prognosis for hip fracture is hopeless and will always result in euthanasia.
Miniature horses, with enough rest, can form a false joint between the fractured end of the thigh bone and the pelvis and regain a reasonable level of soundness.
Given the wide variety of injuries that can result, it is vital to be vigilant when exercising at this time of the year. Watch out for uneven, poached surfaces that are slippery on top and hard underneath, when there will be a paucity of grip. Some people choose to use studs in these conditions.
On the road
Roadwork, traditionally the mainstay of a horse’s fitness programme, tends to be less demanding on the soft-tissue structures (the tendons and ligaments) due to the push-back from the surface.
It is more concussive on the joints, however, and while variety of work is good, too much roadwork can lead to joint pain.
It is important to be mindful of varying road surfaces, such as worn tarmac, and the camber. Watch other riders and their horses up ahead, because whatever is happening to them is what you and your horse will imminently be going through.
A horse may be more prone to slip as he comes closer to his shoeing date. Any temptation to increase the number of weeks between shoeing sessions should be resisted – it is all about toe length and balance, rather than how worn the steel is. Regular shoeing is vital in the prevention of strains, since correctly maintained feet will reduce the likelihood of a horse tripping and help him maintain his balance on challenging surfaces.
Should a horse appear to be suffering limb pain, subtle signs to watch out for are reluctance to work, shortening of the stride and unwillingness to go forward. More obvious indications would be a head nod at trot, signalling forelimb lameness, or a failure to come through with a hind limb when the problem is behind. Visible signs may include filling of the affected leg, especially if the swelling is sore on palpation.
Well-fitting boots will protect injury from impact, but will not prevent strains. The boots should be clean and dry, as should the legs they are put on, to prevent chafing of the skin.
After exercise, hose any mud from the legs and towel them dry. Stable bandages can help prevent them filling overnight.