Tendon injuries happen in one of two ways: sudden tears or ruptures from a single overloading event (an injury) or chronic strains from overuse. The former are usually recognised immediately after an athletic episode and usually have the hallmarks of heat, pain when touched, and obvious swelling. On the other hand, the latter tends to result in low-grade chronic lameness that can be difficult to diagnose.
The most commonly injured tendons and ligaments in non-racing horses are the suspensory ligament, the deep digital flexor tendon (DDFT), the check ligament and the superficial digital flexor tendon (SDFT).
Cause of tendon injuries
There is little information about specific risk factors for tendon injury; however, training regimen, footing, and conformation are thought to play a role in injury. Most tendon injuries are reported in racehorses, but they are diagnosed in all performance horses. In recent studies of racing over fences, horses with a valgus conformation (turned in at the knee) or increased fetlock joint angle (from long, thin pasterns or long toes and low heels) have increased the risk for SDFT injury. Research shows that elite eventing and showjumping result in an increased risk for SDFT injury, and showjumping increases the risk of DDFT injury, while the risk for hindlimb suspensory desmitis is seen to be increased with dressage.
Did you know?
Horses with certain conformational traits, such as long pasterns or straight hocks, may be more prone to tendon injuries.
Treatment
The way a tendon injury is handled upon discovery can make a big difference to the ultimate outcome. Immediately after the injury, the aim is to combat inflammation and swelling. This is best accomplished with cold therapy, such as icing or cold-hosing, compression with bandaging, systemic medications like a non-steroidal anti-inflammatory drug, and box rest.
Although tendon scarring as it heals cannot be prevented, the goal is to make the scar tissue as functional as possible. This is achieved using controlled exercise as part of a rehabilitation programme. Periodic re-evaluation with ultrasound helps to determine the healing progress and allows the program to be altered, depending on how the tendon is healing.
A number of adjunctive therapies can also be used to help tendons heal, including extra-corporeal shock-wave therapy, therapeutic ultrasound and low-level laser and magnetic therapy. However, not all of these have clinical evidence to back them up. Biological therapies such as platelet-rich plasma (PRP), autologous conditioned serum and mesenchymal stem cells injected directly into a tendon injury under ultrasound guidance have shown some promise at either speeding healing, improving the quality of the healed tissue or helping to reduce the incidence of reinjury. More work is definitely needed to understand exactly how these treatments work and what injuries are best addressed using them. This is a very active area of ongoing research.
There are also some tendon injuries that can benefit from surgical intervention such as injuries of the suspensory ligament in the hind limbs, the deep digital flexor tendon and the superficial digital flexor tendon when they are injured in a tendon sheath or bursa.
What is PRP?
Platelet-rich plasma (PRP) is a concentrate of platelet-rich plasma proteins derived from whole blood, centrifuged to remove red blood cells. It has a higher concentration of growth factors than whole blood, which are critical for tissue repair and regeneration. PRP is used in various medical fields, including veterinary medicine, to promote the healing of injuries.
In horses, PRP is commonly used for the treatment of tendon and ligament injuries. The growth factors in PRP help to stimulate the healing process in these soft tissues, which have a limited blood supply and, therefore, heal slowly.
The process of using PRP in horses typically involves the following steps:
- Blood collection: A sample of the horse’s blood is collected in a sterile manner.
- Preparation of PRP: The blood sample is then processed, usually by centrifugation, to concentrate the platelets and separate them from other blood components.
- Ultrasound-guided injection: The PRP is injected directly into the injured area, often under ultrasound guidance, to ensure precise placement.
The use of PRP in horses has shown promising results in accelerating the healing process, reducing inflammation, and improving the quality of the repaired tissue. However, it is important to note that PRP therapy should be part of a comprehensive treatment plan, which may also include rest, controlled exercise, and other supportive therapies. The decision to use PRP should be made in consultation with a veterinarian who is experienced in treating equine injuries.
Recovery
When a horse injures a tendon, recovery is going to be slow and sometimes proves impossible. Prognosis is entirely dependent on the severity and location of the injury but typically ranges from fair to guarded for future athletic use. An owner should expect that the horse will be out of full work for nine to 12 months while the injury heals. Unfortunately, horses who have had a tendon injury are highly prone to reinjury.
The way the rehabilitation is handled can make a huge difference in whether the horse is able to return to his previous activity levels. As humans, we can rest by taking weight off the limb, but this is not possible for horses, so exercise has to be reduced as much as possible and only, very gradually, reintroduced. Exercise programmes must be followed strictly, as even compared to the most expensive treatments, early, controlled exercise of the tissue is the most essential aspect of healing. However, this is a delicate process as overloading too early can reinjure the tendon. Getting this balance between exercise and rest right is the difference between success and failure of rehabilitation.
Prevention
Preventing tendon injuries is always preferable to treating them. Strategies for prevention include:
- Performing a proper warm-up: Ensuring a thorough warm-up before intense exercise is essential.
- Regular conditioning: Maintaining a consistent exercise routine can help strengthen tendons and muscles.
- Appropriate legwear: Using boots or wraps can provide additional support to the tendons during exercise. Just beware of overheating due to boots, which has also been shown to damage tendons.
- Cross-training through conditioning on different surfaces: Conditioning your horse to different types of terrain can help to strengthen soft tissues and reduce the risk of injury. All of this conditioning must be done in a controlled fashion, and each different surface must be introduced gradually.
- Beware deep and uneven footing: Surfaces that are too soft or loose absorb shock forces well but lack support. This type of footing can increase the risk of tendon and ligament-related injuries, such as over-extension. Similarly, exercising on uneven surfaces increases the risk of strain and or injury to tendons.
- Monitoring workload: Avoiding overtraining and monitoring your horse’s workload can help prevent overuse injuries.
- Regular hoofcare: Regular hoofcare is vital for balanced feet and balanced feet support the rest of the horse’s body.
- Regular check-ups: Routine veterinary exams can help catch potential issues early.
Final thoughts
Tendon injuries can be a significant setback for both horse and rider, but with proper care and management, as well as dedicated rehabilitation, many horses can return to their previous activity levels. Understanding the risk factors, recognising the symptoms, following a comprehensive treatment plan and working closely with your vet are key to successful recovery.