As horse owners, we all know the troubles involved with keeping our equine friends healthy and sound. Tendons are essential structures in the equine limb and play a critical role in the performance and athletic ability of any horse. Understanding the important role played by tendons can help us undertake measures to reduce the risk of potential injury. Let’s take a deeper look at the role played by tendons, how injuries occur and what treatment options are currently available.
What are tendons?
Tendons are strong bands of connective tissue that connect muscles to bones. They are responsible for transmitting the forces generated by muscles to the bone, thereby facilitating movement. Tendons are primarily composed of collagen fibres, that are arranged in a tightly packed parallel fashion to form strong and durable structures. Tendons have both elastic and viscous properties (also called viscoelastic properties) meaning they can store and release energy, as well as absorb and dissipate energy. This phenomenon allows tendons to stretch and recoil and provides the ability to withstand the repetitive stresses associated with exercise and movement.
Tendons are divided into two groups, extensor tendons and flexor tendons. Extensor tendons are typically located on the front of the limb and enable extension. Flexor tendons run along the back of the limb and facilitate flexion. The deep digital flexor tendon and the superficial digital flexor tendon are two examples and those that are most frequently involved in injuries.
Why, or how do tendons get injured?
Unfortunately, tendons are prone to injury. This is in part down to the excessive forces they must withstand during exercise. Not only must they support the horses’ own weight, but there is also the added weight of the jockey/rider and the forces that are generated by movement of the horse. This can place a significant strain on tendons. Injuries occur where this is an excessive or prolonged strain that can overwhelm the viscoelastic properties of the tendon. When an injury does occur, it is common practice for the opposite limb to be monitored for potential breakdown and subsequent injury. Aside from these injuries, it is also possible to obtain an injury from an external source, i.e. kicks, overreaching, or lacerations/wounds.
What are the signs of a tendon injury?
The severity of an injury and subsequent damage will determine how they present and what signs we may see. Typical signs of a tendon injury include:
- Heat or swelling in the affected area
- Pain or lameness
- Decreased range of motion
- Changes in gait or movement
How do tendons heal?
There are a number of stages involved with the healing process of a tendon injury. Each phase is important and plays a key role in the overall healing process:
- Inflammatory Phase: the initial phase of tendon healing, which typically lasts for 3-5 days following injury. The body’s immune system responds to the injury by sending inflammatory cells to the damaged area. The inflammatory phase is characterised by heat, swelling and pain in the affected area.
- Repair Phase: the body begins to repair the damaged tendon. The duration of this phase is variable depending on the extent of injury and can last from several weeks to months. The body begins to lay down new collagen fibres to replace the damaged tissue. Appropriate therapy and controlled exercise play a crucial role during this repair phase and reduces the potential for scar tissue.
- Remodelling Phase: the final phase of tendon healing. This phase can last anywhere from several months to a year. The body continues to lay down new collagen fibres and remodel the tissue. This helps to improve the future strength and flexibility of the tendon. Following a strict treatment and exercise plan is essential to aid the proper alignment of the new collagen fibres and guard against future injury. It is important not to cut this phase too short by rushing a return to competition or full training as re-injury is very possible.
What treatment options are currently available?
The treatment of choice will generally depend upon the type and severity of injury. Your veterinarian will be able to assess the injury (usually via ultrasound examination) and offer you the most appropriate rehabilitation program for your horse. Your horse’s treatment will be tailormade to suit their needs, but some of the options currently available include:
- Cold Hosing: plays an important role in the “Inflammatory Phase” of healing. Helps to reduce inflammation and swelling which may aid the overall healing process. It is quite common for this to be performed in combination with other approaches such as rest and controlled exercise.
- Rest and Controlled Exercise: the need to rest cannot be overstated for any tendon injury. The horse must be provided with sufficient time to allow the tendon to properly heal. Stable rest plays a key role in this approach. Controlled exercise should only follow after an appropriate assessment has been performed. This approach will usually only be considered where the injury in question is of a relative minor nature.
- Non-Steroidal Anti-Inflammatories: these medications will help to control and limit the extent of inflammation that is seen. I’m sure most owners will be familiar with these but it is important to be careful, as they can mask pain and as such give the opinion that everything is okay. Remember, even minor injuries need time to heal properly.
- Platelet-Rich Plasma: also known as PRP. This process involves drawing a blood sample from the horse, processing it and injecting into the injured area. PRP delivers concentrated platelets and growth factors that help to accelerate the healing process.
- Stem Cell Therapy: this process involves harvesting stem cells from the horse’s own bone marrow and injecting into the injured area. A sample will typically be taken from the sternum (breastbone). Stem cell therapy can prove to be extremely beneficial in improving the quality of the repair taking place.
- Shockwave: this is a non-invasive therapeutic approach involving high-frequency sound waves that apply vibration to the healing tissues. It is normal for this type of therapy to be repeated several times over the recovery period, typically at intervals of one to two weeks.
- Laser: is currently used to promote healing and reduce inflammation by stimulating cell metabolism and increasing blood flow to the injured area. There has been some thoughts that this may help reduce pain and even improve the range of motion in the affected limb.
The biggest thing to remember with any tendon injury is that recovery is a long slow process and requires a lot of patience on the part of you, as an owner. However, with good management and care, most horses can make a full recovery and potentially return to their previous level of activity.
Ian Rountree MVB
For recommended tendon products go to Tendon Gel or Flexotendon.
