PELVIC PROBLEMS – UNDERSTANDING SACROILIAC DISEASE IN HORSES
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Sacroiliac disease is a relatively common condition that affects the sacroiliac (SI) region in horses. The sacroiliac joints, located where the spine meets the pelvis, play a crucial role in the horse’s locomotion and ability to carry weight. Damage and dysfunction in the joints and the region generally can give rise to obvious pain and lameness, but symptoms are often more subtle and not immediately apparent. Either way, issues in this sacroiliac area can significantly impact a horse’s performance and overall well-being.
Anatomy of the sacroiliac joints
In horses, the section of the backbone that runs through the rump area inside the pelvis is called the sacrum, and on each side of the body, it’s connected to a part of the pelvis called the ilium. This connection is called the sacroiliac and is a separate area on both the left and right sides of the body.
The sacrum and ilium are bonded with tight connective tissue, which is pretty much immobile in a sound horse. The muscles in the area provide further support. This allows a horse’s weight and the powerful forces required for movement to be transferred back and forth between the backbone and the pelvis efficiently and without any discomfort.
In sacroiliac disease, this tight bond between the sacrum and one or both sides of the ilium becomes weakened and a little looser. As a result, during movement when weight is transferred from the legs to the body, the weakness in the bond allows a small amount of movement between the sacrum and the ilium, which then causes inflammation and pain.
Over time, scar tissue accumulates around the sacroiliac area, and calluses can form on the bony surfaces, making the union between the bones weaker still and the problem worse.
Causes of sacroiliac disease
Sacroiliac disease can be a primary problem or secondary to other orthopaedic issues. Primary damage to the sacroiliac region may result from a specific traumatic incident, such as a fall or slip. In these cases, there can be a sudden significant strain to the sacroiliac area caused by the impact, and the tight fibres bonding the sacrum to the ilium can be torn or strained. Whether one side of the sacroiliac region is affected or both will depend on the nature of the incident.
Sacroiliac disease can also result from repetitive strain and overuse. This is usually found in conjunction with another underlying problem, most commonly proximal suspensory disease in the hindlimbs, hock joint arthritis (bone spavin) or kissing spines. However, any prolonged lameness or severe conformational fault could be responsible. Due to pain, these issues tend to cause long-term asymmetry within the body, particularly the pelvis, so the forces acting on the sacroiliac area are abnormal. Over time, this causes a gradual weakening of the fibres connecting the sacrum and ilium, and their bond is loosened.
Symptoms of sacroiliac disease
Often, there are minimal visible signs of sacroiliac problems. Pelvis asymmetry is present in some horses – this is best viewed from behind, with the horse standing square. The gluteal muscles may be different sizes, or, more usually, the bony prominences at the top of the pelvis (the tuber sacralae, often known as hunter’s or jumper’s bumps) aren’t level. Horses may show pain when pressure is applied to the back or pelvis, and there is tension in the muscles, but the degree of lameness varies.
Sometimes, following a specific recent trauma, lameness is obvious and only in one limb, but often, a subtle loss of performance across both hindlimbs is all that is noticed. There is likely to be a lack of drive from behind, and the rider feels the horse is pulling from the front limbs rather than pushing forward from the hinds. Elevation and stride length are often decreased in the hindlegs, and the horse might frequently disunite in canter.
Fast fact
If there’s damage to the sacroiliac area, there’s likely to be a mild worsening of lameness after a hindlimb flexion test or when the horse is ridden.
The main symptoms to look out for in sacroiliac disease:
Performance issues: Reluctance to engage the hindquarters, difficulty in cantering, or reduced jumping ability.
Lameness: Subtle or intermittent lameness that may shift from one hind leg to the other.
Back pain: Sensitivity or pain when the back is palpated, often noticeable during grooming or saddling.
Stiffness: Stiffness, particularly after exercise or rest, which can affect the horse’s gait.
Behavioural changes: Changes in behaviour, such as reluctance to move forward, bucking, or resistance to being ridden.
Diagnosis of sacroiliac disease
While sacroiliac disease can be suspected in certain types of lameness, as noted above, many other problems can also present similarly, so these need to be ruled out. If a clear lameness is visible, the sacroiliac area can be numbed to see if there’s improvement in the gait, but this is reasonably unreliable. Ultrasonography of the sacroiliac regions via the rectum can also be used as an additional diagnostics tool, but, again, it can be pretty unreliable. Instead, nuclear scintigraphy is the primary way to diagnose the problem, as clear abnormalities will be seen on this scan.
Did you know?
For nuclear scintigraphy, the horse is injected with a radioactive compound that travels through the bloodstream and attaches to any injured parts of the skeleton. The machine can detect this radiation, highlighting any diseased or damaged areas.
Treatment
Treatment aims to allow the sacrum and ilium to regain their strong bond, which often takes many, many months. Time and rest with controlled, non-ridden exercise, including lungeing, long-reining, in-hand walking and walking on a treadmill or horse walker, can be helpful.
Working closely with a certified equine therapist, specific stretches, reversing movements, and polework can also aid in improving flexibility and core strength while allowing the sacroiliac area to heal.
Veterinary treatments can include:
- Giving the horse cortisone injections, using long needles directly into the sacroiliac regions, is anti-inflammatory and relieves pain.
- Administering shock wave therapy for pain relief and to promote the growth of new blood vessels in the damaged areas and, therefore, healing.
- Supplying oral anti-inflammatories and pain relief.
Note
In cases where the sacroiliac disease is secondary to another injury, it’s essential to address the underlying problem first.
Prognosis
Unfortunately, the outlook for many horses with sacroiliac disease is not optimistic. Due to a horse’s size and weight, re-establishing a robust, fibrous connection that has been weakened is challenging, particularly if the problem is long-standing.
Further, when another underlying injury has caused the sacroiliac disease, the overall outcome often depends on the prognosis of that condition. For example, kissing spines can be successfully corrected surgically, whereas proximal suspensory disease is much harder to control.
Ultimately, time, patience and hard work in rehabilitation are essential. Recovering from a sacroiliac injury takes many months, and this can be frustrating, particularly when you’ve spent long periods carrying out the rehabilitation exercises without seeing much improvement. As hard as it might be, it is important to stay positive. Although some may require ongoing treatment, most horses will recover sufficiently to be rideable to some level.
Prevention
Preventing sacroiliac disease involves maintaining the horse’s overall health and fitness:
- Conditioning: Gradual and consistent conditioning programs to build strength and flexibility.
- Proper training: Ensuring that training programs are appropriate for the horse’s age, fitness level, and discipline.
- Saddle fit: Regularly checking and adjusting saddle fit to avoid undue pressure on the horse’s back which can cause compensatory issues in other places, such as the SI joint.
Conclusion
Sacroiliac disease is a complex condition requiring a comprehensive diagnosis, treatment, and management approach. Unfortunately, the prognosis is not overly favourable. However, with proper care and attention, many horses can return to some level of meaningful work and lead comfortable, productive lives. Working closely with veterinarians, trainers, and other equine professionals is essential to ensure the best outcomes for horses affected by sacroiliac disease.