If you have ridden horses for long enough, it’s likely you’ll have experienced that terrifying feeling of a horse buckling underneath you as he trips. It’s a dangerous situation for both horse and rider and a risk we should look to minimise, even though horses are normally adept at rescuing themselves before they hit the ground.
Due to the work we ask our horses to perform, occasional tripping is unavoidable, but when does it become a concern?
Tripping can be considered abnormal if it occurs more than twice per ridden session or if the horse always stumbles on the same leg. An additional warning sign is when the problem can be reproduced consistently during a certain movement or situation, such as exercising up or down an incline or when the horse is asked for increased poll flexion.
A particularly poor or slow recovery from a stumble is also concerning. Horses usually snap back upright as fast as possible, almost embarrassed by their ineptitude, so a laboured return to their feet warrants investigation.
There are a variety of tripping causes that can be ruled out by an owner or through a simple veterinary examination. Tripping in a young, unfit, unbalanced or distracted horse should improve with age and/or training. An obese animal is likely to trip less with an appropriate diet and exercise programme. Partially sighted animals and those with exercise intolerance or advanced cardiac disease are all more likely to trip when exercised, but these conditions would be diagnosed swiftly by a vet due to signs other than tripping.
Further investigation will require a detailed veterinary history and clinical examination, as there is often more than one condition at play.
Assuming there are no immediately obvious causes, addressing any foot issues will be beneficial, whatever the cause of tripping, and is often the solution in simple cases. Long toes on front or hind feet will cause delayed “breakover”, meaning the foot is slower to move in front of the horse and down onto the ground to bear weight.
In addition, a longer toe is closer to the ground through the arc of flight, so is more likely to cause a stumble. And excessively long hind feet can interfere with the heels of the front feet.
Careful trimming, with input from both vet and farrier, can improve foot shape and balance dramatically to reduce stumbling. Rolling the toe — by rounding the front edge of any chosen shoe — or using bar or reverse shoes, will alter the action of the foot during motion and can improve the biomechanics of the limb.
A horse who continues to trip should be assessed for the presence of orthopaedic disease causing pain or lameness, or a neurological condition affecting limb coordination.
Orthopaedic conditions can mean a horse adapts his movement to minimise the degree of pain, potentially causing tripping.
An examination — with flexion tests, lungeing on soft and hard surfaces and ridden exercise — will often demonstrate a lameness, which can then be investigated with nerve and joint blocks to isolate the source of pain. Diagnostic imaging such as X-rays, ultrasound scans, MRI or CT will follow to identify the severity of the problem.
Causes of lameness-induced tripping include navicular disease, coffin joint pain, ringbone and arthritis of the fetlock or knee. These are usually straightforward to diagnose and, depending upon severity, are often manageable with a combination of remedial shoeing, intra-articular medication and controlled exercise. Regular physiotherapy is beneficial, along with non steroidal anti-inflammatory medicines prescribed by your vet, such as phenylbutazone (bute), and a good-quality joint supplement.
Problems higher up the leg can also produce stumbling, as they will limit the degree of protraction (extension of the limb) during locomotion. Shoulder issues, such as arthritis or bicipital bursitis (inflammation of a fluid-filled joint bursa, or sac), can present in this manner.
Some horses may stumble due to an orthopaedic issue without appearing lame. The neck, back and pelvis are all on the shortlist in such cases, but identifying the source of pain can be challenging. Blocks of these regions are technically difficult and carry a risk of inadvertent anaesthesia of major nerves, which can cause the horse to become ataxic (wobbly).
Without obvious lameness, it can be tricky to assess improvements in a horse’s movement after local anaesthesia. If tripping is intermittent, it is hard to be sure of genuine improvement during a short assessment after nerve or joint blocks. Feedback from an experienced jockey who can ride the horse before and after any blocks is one of the most valuable aids to interpretation.
Suspect areas can be screened for injuries with diagnostic imaging, which may include nuclear scintigraphy (bone scanning). Arthritis in the neck, back or pelvic region can be treated with ultrasound-guided intra-articular corticosteroid injections.
“Kissing spine” lesions can be treated with local infiltrations of corticosteroids or may benefit from surgery, while sacroiliac disease can be managed with anti-inflammatories and shockwave therapy, among other options.
Physiotherapy and targeted rehabilitation programmes also help in improving the mobility of affected areas, maintaining flexibility and developing the horse’s core strength.
Tipping the balance
Neurological disease is the biggest worry, particularly with the horse who trips with his hindlimbs. This can be difficult to diagnose in subtle cases.
A common cause is “wobblers” syndrome, which occurs when incorrectly formed vertebrae in the neck pinch the spinal cord. Arthritis of the neck joints or the growth of new bone (callus) around a fracture site can also create pressure on the spinal cord and, in the early stages, cause hindlimb weakness, which can manifest itself as tripping.
If the condition worsens, neurological signs become more obvious and are characterised by difficulty turning in tight circles, dragging of hindlimb toes and sometimes even forelimb incoordination. Neck X-rays will often confirm the condition and dictate the appropriate therapy.
Treatment options range from aggressive nutritional and exercise management in young animals that have developed too rapidly, resulting in neck instability, through to local injections of corticosteroids into affected joints to reduce inflammation. Surgical stabilisation of the neck joints may be an option. Fusion of the vertebral bodies results in around 60% of patients resuming a good degree of athletic function.
There are a wide range of causes of tripping and stumbling. If the problem proves dangerous or becomes more regular, seek veterinary attention, so the horse can be fully assessed.
Ref Horse & Hound; 20 June 2019