Suspensory Ligament Injury in Horses

Among all tendon injuries in horses, a suspensory ligament injury is the most feared by many horse owners. This is because the suspensory ligament is not only a complex structure but also difficult to access, making accurate diagnosis challenging. However, with today's early detection methods, a suspensory ligament injury does not necessarily mean the end of the horse's athletic career.

What is a suspensory ligament injury?

The suspensory ligament injury is the most common and complex cause of a lameness in the horse. The fetlock beam starts to become inflamed and thus painful after a strain or strain. If the horse is lame and the fetlock beam has been diagnosed as the cause, this means at least six months off for the horse. As a rule, horses need eight to twelve months before they are fully able to bear weight again.

Suspensory ligament injury can occur in any horse at any age. The fear of the diagnosis need not be too great for horse owners in the meantime. Nowadays, fetlock ligament damage has a good chance of being cured because, thanks to better diagnostics, it can be detected and tackled at an early stage - and not just when it is already too late.

Structure and function of the suspensory ligament

The suspensory ligament is not a single tendon. It is much more a complex of tendons, ligaments, and a small amount of muscle, in conjunction with bone and joints. The amount of muscle in the fetlock beam remains a mystery to this day, as it can vary in horses. It is said that trained horses have fewer muscle fibers in the suspensory ligament injury than untrained ones. However, the higher the muscle percentage, the more unstable the supporting complex of the fetlock beam becomes, making the horse more susceptible to injury.

The suspensory ligament is 20 to 30 centimeters long, which is why it is still difficult to localize the origin of the injury. It attaches below the hock joint (or carpal joint) between the splint bones. Here, it is firmly connected to the bone by fibers at the so-called suspensory ligament origin. It then runs along the back of the cannon bone. In the lower third, it divides into two branches: one part attaches to the splint bone, and the sesamoid bone, which acts as a pulley for the fetlock joint. The other part extends forward as a supporting branch of the extensor tendon. Both the connection to the bone and the lower third, where the suspensory ligament is redirected, form critical points—weak spots that are often affected.

With this structure, the suspensory ligament supports the fetlock. On one hand, without its support, the fetlock would touch the ground, making the horse effectively "overreach" to the ground. On the other hand, the suspensory ligament acts as a shock absorber during the support phase and is involved in load absorption together with the superficial flexor tendon. When the horse steps down, the suspensory ligament stabilizes the fetlock joint, helping to prevent excessive hyperextension. The joint has a slight spring to it, rather than being forced down to the ground. This helps counteract early wear and tear. While standing or in the support phase, when the suspensory ligament is under tension, it can be easily confused with the bone. Only when the leg is lifted and the suspensory ligament relaxes does it become soft and flexible.

Since the suspensory ligament is firmly attached to the bone, a strong pull is exerted on the bone itself. This extreme tension relationship is the reason why injuries occur precisely at this point due to chronic overloading. The suspensory ligament is most commonly damaged at the top or bottom, but rarely in the body of the ligament itself. When fine fibers tear away from the bone, it is referred to as a suspensory ligament origin disease, which often affects show jumpers in the front limbs and dressage horses more in the hind limbs. Injuries at the suspensory ligament origin do not always present with swelling and heat, which is why they are sometimes not recognized immediately. Consequently, undetected suspensory ligament injuries can become chronic.

Additionally, the length of the fetlock is an important factor. The shorter the fetlock, the smaller the lever that exerts strain on the elasticity of the suspensory ligament. Horses with short fetlocks are less likely to experience issues with the tendon, as they have better load-bearing capacity. In contrast, long fetlocks result in a larger lever and, consequently, greater tensile forces acting on the suspensory ligament.

Symptoms: Recognizing a suspensory ligament injury in horses

The symptoms of a suspensory ligament injury can be both subtle and varied. This makes it difficult to make an accurate diagnosis on a case-by-case basis. However, if any of the following symptoms or other inconsistencies are noticed, the veterinarian should be called immediately. After all, the vet can put one and one together.

• Lameness, especially on soft ground
• Swelling associated with warmth (when the corpus or ligament is damaged at the coxae; injuries at the fetlock origin are associated without swelling or warmth)
• Pain reaction when pressure is applied to the tendon or during the flexion test

Not all symptoms always accompany a suspensory ligament injury, which is why it is difficult for some horse owners to recognize. Even subtle tact impurities when riding can indicate damage. In horses that are ridden heavily bridled, so that the pitching movement does not occur at all, the lameness remains undetected.

Causes of damage of a suspensory ligament injury

• Acute overload symptom due to stepping, hard turns. The fetlock joint is a hinge joint that allows only limited rotational movement.
• Repetitive trauma: the tendons take on too much load in the medium term, but are not given the opportunity to regenerate
• Sinking too deep into soft ground
• Lack of variety in the soil load
• Insufficient level of training or lack of training
• Muscle fatigue
• Overstraining through too many trot reinforcements and lateral gaits: Due to the shearing movement, the horse does not step flatly, the fetlock support has to hold back more strongly.
• Long bondage
• One-sided load due to misalignment and imbalance
• Poor hoof care, too long toes restrict hoof mechanism
• Hereditary weak tendons
• Breeding defects, overweight
• Nutrient deficiency or overload of the liver as a detoxification organ (harmful substances are stored in tendons)

Experts observe a more frequent occurrence of pastern damage today than in the past. The reason is the specialized breeding of horses: Whereas decades ago horses were bred with natural movement and had to be trained to move in space, modern bred young horses already show oversized movements. This leads to an early overloading of the structures and thus to damage in the tendons and joints. Furthermore, it can be observed that about 60% of pastern damage is found in the forelegs. 

Diagnosis

To determine fetlock ligament damage in a horse, the veterinarian proceeds as with any other tendon damage as with any other tendon damage: If a tendon injury is suspected, the horse is first presented at a walk and trot on hard and soft ground. If the horse lames more on soft ground than on hard ground, this may be an indication that the joint is also involved. Leading on a bent line is also important in diagnosing fetlock ligament damage. Next, the flexion test is still performed to see exactly where the injury exists.

Since the symptoms of pastern damage can vary from horse to horse, prolonged lunging can also be important for diagnosis. This is because some horses only show signs of a Lameness.

If the leg around the tube is already swollen and warm, the pre-trotting and flexion test is not absolutely necessary. Then the veterinarian can go straight to the ultrasound to determine the extent of the injury.

However, if the horse is lame without the veterinarian being able to palpate swelling or warmth, the horse's leg must be hosed down. In this way, the veterinarian feels his way step by step to the painful area in order to locate the cause of the lameness. Once this is located, an ultrasound can be performed.

Depending on the horse's impairment and perception of pain, the fetlock beam injury is irritation, strain or inflammation. Irritation of the fetlock beam exists when the horse is minimally impaired. Strength symptoms indicate a strain, while inflammation involves heat and swelling as the body's response. If it is a complete tendon damage, fibers of the complex are torn off. These can then be seen diffusely, at the edges or as a hole in the middle as dark spots on ultrasound. You can find more information about tendon damage in horses in the article on this topic.

Once the veterinarian has made a diagnosis and identified the extent of the damage, an appropriate treatment method can be applied.

Preventing a Suspensory Ligament Injury

Prevention is the best therapy for the horse's legs. To prevent fetlock ligament damage, you should:

• Riding the horse gently
• Warm up the horse with at least 20 minutes of walking
• Do not overdo it with side gaits and trot reinforcements
• Watch out for hidden holes
• Avoid too frequent riding on deep, soft (indoor) ground
• Provide variety in ground conditions to exercise the musculoskeletal system with its tendons and ligaments
• Finding variety and a good balance in horse training

Therapy and treatment options for suspensory ligament injury

The ligament and tendon system of a horse is a system with a weak blood supply. This makes the healing process slower than in other areas of the body. Curing a suspensory ligament injury in horses therefore requires time, patience, and good blood circulation. There is no panacea, nor should any treatment method be preferred, but the best one for each horse should be determined.

If it is not a tendon rupture, movement can be included in the therapy plan at an early stage after a short period of box rest. This is because controlled exercise stimulates blood circulation and thus also the removal of harmful substances. It is imperative to talk to the veterinarian about the start of the walking therapy and the length of the units.

Many horse owners are unsure how much they can expect their horse to suffer from a suspensory ligament injury. The fear is great that initially small injuries may become chronic. As a rough guideline, one can say: If the horse is lame even at a walk, strict box rest is required. If the horse is lame at a trot, it can be led at a walk. If the horse is not lame, it can trot appropriately.

For details on the intervals at which the stride sequences can be extended, see the article on tendon damage in horses. For a training plan after a break due to injury, see the article on training plans.

At the same time, the horse can be given anti-inflammatories to reduce the swelling and relieve the painful pressure on the nerves. For external application, blood circulation-promoting ointments or gaiters with ceramic fibers help. However, this should be done after the acute phase, otherwise the inflammation will spread further.

Furthermore, there are therapeutic approaches for suspensory ligament injuries that are intended to set the natural repair mechanisms of the tendons in motion:

Autologous blood therapy

In autologous blood therapy, processed blood plasma is injected directly into the affected suspensory ligament. This is primarily practiced in cases with diffuse ultrasound images showing many small holes in the tendon. The goal of using autologous blood is to accelerate the regeneration processes. However, this therapy does not necessarily shorten the healing time; instead, it results in less scar tissue, which is less resilient and elastic than the original tissue.

Shockwave therapy

If the injury is located at the suspensory ligament origin, shock wave therapy is applied to the tissue. Known from human medicine for breaking up kidney stones, these shock waves release tissue hormones that positively influence bone metabolism and help regenerate any resulting weak points. Additionally, this treatment is intended to achieve pain relief.

Stem cell therapy

There are very good healing prospects for a suspensory ligament injury with stem cell therapy. In this procedure, stem cells are harvested from the bone marrow fluid of a donor horse and injected into the affected area. The stem cells help regenerate new tissue around the damaged suspensory ligament. Stem cell therapy provides the opportunity to initiate the "natural" healing process of the suspensory ligament. However, it is also very expensive, which means that this form of therapy is not feasible for every horse owner.

Lymphatic Drainage & Compression Therapy

Tendons, although poorly supplied with blood, are surrounded by numerous lymphatic vessels. These are directly connected to the deep lymphatic vessels in the body, which are difficult for the equine therapist to access. Damage to the fetlock ligaments produces harmful and inflammatory substances. With the help of lymphatic drainage, the removal of harmful and inflammatory substances is facilitated. This relieves the tendon tissue and thus also the horse from pain. In addition, one can observe how the massage grips support the alignment of the newly formed fibers, making the scar tissue more stable and uniform.

Surgery of the suspensory ligament in horses

Surgery of the pastern is only necessary in chronic diseases or if the pastern origin regularly causes problems. This is because it sits deep, surrounded by the cannon bone, fascia and pastern bone. If this area is swollen, the tissue puts painful pressure on the nerve around the fetlock beam origin. During surgery, the fascia is opened to allow the pressure to escape. Only in severe chronic cases is the permanently irritated nerve removed. Since this is a massive operation, a very good sonographic evaluation is important beforehand. After the operation, a thickening may remain externally. Nevertheless, the horse can be fit again after four to eight weeks. Nevertheless, if the horse has had fetlock surgery, the Animal Welfare Act prohibits the horse from returning to competition. Even light work should be done with caution.

Another surgical option is to drill holes in the long bones. This is to stimulate the structures to grow new blood vessels around the fetlock origin to increase blood flow.

Support the healing of the suspensory ligament injury through appropriate feeding

It is not definitively clear whether nutrition significantly impacts the recovery from a suspensory ligament injury. This is because the aforementioned therapeutic approaches and their research are often conducted without reference to nutrition. Therefore, it is difficult to determine whether supplements, herbs, etc., influence the healing process. However, evaluating the horse's feeding schedule certainly benefits its overall health. What is certain is that the body requires nutrients to function properly, and tendons and ligaments also need trace elements to maintain their health.

When treating a suspensory ligament injury, it is essential to focus on a diet that compensates for any deficiencies. Potential nutrient deficiencies can be most effectively identified through a hair analysis or a comprehensive feed analysis, as deficiencies in certain nutrients often become evident in blood tests only at a later stage.

The decisive factor in suspensory ligament or tendon damage, in general, is the relief of the liver. It is responsible for detoxification and thus for the elimination of toxins, waste, and inflammatory substances. If the body regenerates after a tendon damage, it needs a strong liver. This can be relieved by eliminating ensiled feeds, sugar and starch, lactic acid bacteria, and brewer's yeast, such as those found in probiotics, from the feed plan. Instead, lean hay, mineral feed, a salt lick, and water at your free disposal are all the feed the horse needs to cure a suspensory ligament injury.

Important nutrients for strengthening tendons and ligaments are the following:

• Magnesium
• Manganese
• Selenium
• Zinc
• Copper

These are only absorbed in small quantities via the basic feed and must therefore be fed in addition. The amount must be discussed with the veterinarian.

Furthermore can

• Green-lipped Mussel
• Spirulina algae
• MSM (sulfur compound)
• Collagen 
• Chondroitin and
• Silica in phases

strengthen the tendons and ligaments. In a completely natural way, one can do besides herbs to the fetlock carrier something good. However, these must be fed over a longer period so that they show effect. Some herbs, like devil's claw, affect the stomach and should therefore only be fed in cycles. Therefore, the feeding of herbs in the case of a suspensory ligament injury should also be clarified in advance with the attending veterinarian. Tendon herbs that relieve pain, promote circulation, and have an anti-inflammatory effect are:

• Devil's Claw
• Willow bark
• Rosehip
• Meadowsweet
• Ginger
• Nettle
• Watercress
• Hawthorn

‍Fittingin the event of fetlock damage

In the case of a suspensory ligament injury, the horse must not sink into deep, soft ground during recovery, as this can lead to overloading the suspensory ligament complex. For this reason, many horse owners prefer using egg bar shoes and round shoes with a closed back. These are intended to prevent the horse from sinking and to relieve the tendon complex. For a long time, they were considered the gold standard. However, some experts view shoeing critically in cases of suspensory ligament injury. On one hand, shoes can block the horse's natural hoof mechanism. On the other hand, the height created by the closed shoes raises the horse's hindquarters, which contradicts the natural hoof position. Additionally, horses that previously wore open shoes or were barefoot may struggle with egg bar shoes, as they tend to step carefully, which should be avoided for the therapy of the suspensory ligament. The horse should ideally move as naturally as possible and bear weight on its leg normally.

Experts and horse owners who recommend orthopedic shoeing in the event of fetlock ligament damage are opposed to the "against" camp. It is therefore necessary to find the best solution for the respective horse in cooperation with the veterinarian and farrier.

FAQs: Frequently asked questions about fetlock ligament damage in horses 

Is a suspensory ligament injury in horses curable?

Today, a suspensory ligament injury in horses no longer has to mean the end of the horse or its career. This is because they can be detected and treated at an early stage. A suspensory ligament injury has a good chance of healing, but depending on the extent, it means a longer time out. The injury must be completely healed before the ligament-tendon complex is fully loaded again. If the irritated fetlock ligament is overloaded too soon, the problem can develop into chronic suspensory ligament injury.

By the way, you can read a more detailed regeneration process of a tendon damage in our article about tendon damage in horses.

How long does a suspensory ligament injury last in a horse?

How quickly a suspensory ligament injury heals depends on the degree of damage, the location, and consequently the treatment options. In general, 8 to 12 months of rest should be planned until the horse is fully fit to ride again. However, this time does not mean complete rest, but rather continuous, gradual build-up and introduction to weight-bearing. This will reduce the formation of scar tissue. It is important to maintain a balance between rest/recovery and exercise.

A precise therapy and training plan for a suspensory ligament injury is comparable to that of a typical tendon injury in horses. You can read about this in the article on tendon injuries in horses, and it should always be discussed with the treating veterinarian.

Does the healing process of a suspensory ligament injury take longer in older horses?

In older horses, the healing process of a suspensory ligament injury can take longer because the entire metabolism runs slower. However, this statement cannot be generalized, as every horse is different. Special caution is indeed required with older horses, as a suspensory ligament injury can quickly become chronic. Since the riding career is often over for older horses anyway, the focus then is often just on alleviating symptoms. Attempting to reverse the processes and achieve a complete recovery is frequently futile.

What is more beneficial in the case of a suspensory ligament injury: controlled walking or standing in the meadow?

Immediately after the injury, the horse should not be put out to pasture, where it can move uncontrollably and possibly cause further injury. After the acute phase, controlled exercise can already be started to provide a stimulus for the tendons to heal. To allow as little inelastic scar tissue as possible to form, controlled movement through a restorative step program is essential. Only in exceptional cases, when the possibility of walking the horse for several months does not exist, can pasture be considered as the sole exercise option. However, the horse should not buck around if possible, which would cause the tendon to be overstretched again. Each horse owner knows his horse best and should make the best decision for him.

Can you ride a horse with a suspensory ligament injury?

If the suspensory ligament injury is detected and treated early, the horse can regain its fitness for sport after full recovery. In acute cases and during the first three months, the horse should, of course, not be ridden. Any exercise should be approached cautiously, as the rider would only add unnecessary weight to the damaged suspensory ligament. Jumping or pole work is also off-limits, especially in the initial months. However, this period doesn’t have to be boring, as groundwork with the horse can bring a lot of variety to the daily routine. After about a year, with a sensible training plan, the horse can be fully operational again and ready for competitions. In contrast, horses with chronic suspensory ligament injuries that required surgery are prohibited by animal welfare laws from returning to competitive sports. An operated suspensory ligament injury marks the end of the horse's athletic career.