A hefty fall can leave a horse winded, but how do we know if they have suffered internal injury, Gil Riley MRCVS asks?
After a heavy fall, it is important to establish what, if any, injuries the horse has sustained.
If he can’t stand, he may be winded – a spasm of the diaphragm as a result of sudden force applied to the abdomen – or have a broken limb or an injury to the spine or head.
A horse who is merely winded should be back on his feet within 10 to 15 minutes, as if making a miraculous recovery. If he stays down, the likelihood is that much more serious damage has occurred.
A thorough examination should identify any architectural changes to the horse’s external anatomy. Failure to bear weight on a leg could indicate a fractured bone or torn muscles in the proximal (upper) limb; moving the limb may result in crepitus, a grating sound or sensation produced by friction between bone and cartilage in a joint or the
fractured parts of a bone. Injury to the pelvic musculature or the pelvis itself can render a horse very reluctant to walk or weight-bear on one or more limbs.
The challenge is to ascertain whether any damage is superficial or deep, so any vets in attendance must be allowed time and space to examine the animal thoroughly. If serious injury is present, it can take considerable time to gather sufficient clinical evidence to be able to reach an accurate diagnosis.
Bumps and bruises
Falling on heavy ground can cause bruises – ruptures of the small blood vessels (capillaries) underneath the skin. If the ground is hard, damage may be greater, with additional abrasion to the skin.
A deeper bruise presents as a fluid-filled lump called a haematoma, where underlying tissues have bled or oozed serum to create a “balloon” under the skin. The damaged blood vessels bleed until there is sufficient pressure from fluid accumulation within the haematoma to halt the bleeding and allow clotting.
If there is major disruption of deeper tissues, there may be torn muscles as well as bruising. Try to keep the horse calm, since excitement will increase blood pressure and lead to more bleeding.
While the haematoma is developing, it may be possible to control the bleeding and minimise swelling by applying direct pressure and ice to the site – as long as it is in an accessible area where the horse will tolerate it.
Cold should be applied for no more than 20 minutes at a time, and only for as long as the area feels warm and soft. Later, after the haematoma has stabilised, warm packs can increase circulation and stimulate healing.
Haematomas are usually sterile swellings, so there is very little pain or inflammation. Most resolve, if given enough time, so are best left alone.
No attempt should be made to drain a haematoma until the damaged vessels have sealed,
as opening it up may allow bleeding to resume. If it continues to grow, however, then surgery to ligate (tie) the vessel responsible may be necessary. Once a haematoma is “mature”, usually around two weeks after forming, careful drainage with a sterile needle can be considered to minimise long-term scarring or to speed up healing.
If it has developed a subcutaneous pocket, where the skin is no longer attached to the underlying tissue, it may refill with serum. There is also the risk that bacteria is introduced, converting a sterile pool of serum into a painful abscess.
A blood test will help identify the severity of any internal haemorrhage by measuring the haematocrit, the level of red blood cells in circulation. Results must be carefully interpreted, however, as horses have large reserves of blood in the spleen and may not appear anaemic as a result of internal haemorrhage.
High levels of muscle enzymes, proteins found mainly in muscle tissue, will indicate muscle damage. Very high levels are associated with bruising and trauma to the muscles of the hindquarters or back, where most of the muscle tissue is found.
Difficult diagnosis
Ruptures of internal organs such as the spleen or intestine, or the diaphragm (the muscular curtain that separates the chest cavity, or thorax, from the abdomen), are rare.
More commonly, fracture of one or more ribs causes penetration of the space around the lungs, called the pleural cavity. The resulting pneumothorax (collapsed lung), usually evident because the horse is struggling for breath, can sometimes be resolved with rapid surgical intervention.
While many limb fractures are untreatable and result in euthanasia, some may be corrected. Most can be identified using radiography (x-ray), although nuclear scintigraphy may be required to diagnose hairline distortions in the bone (stress fractures), or fractures within large amounts of muscular tissue impenetrable to x-rays or even ultrasound (in the femur or hip, for example, in the larger horse).
Examination of the pelvis is difficult due to its musculature; the only palpable areas are the points of the hip, termed the tuber coxae, and the tuber sacrale at the highest extremity of the back.
Direct impact with the ground can result in a piece of the tuber coxae breaking off. Since the tuber coxae serve as the origin of some of the gluteals, the largest muscles of the hindquarters, recovery can be prolonged and lameness may be long term.
After a fall, swimming can be a useful addition to box rest and walking out, as it allows the horse to recuperate without weight bearing and to achieve mobility of damaged muscles and joints. Physiotherapy can help return elasticity to tissues and mobilise scar tissue, minimising the formation of constrictions and adhesions and breaking down those already present.