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Tendon Injuries

May 2018

Tendon injuries

Written by BHS Stewart Hastie Veterinary Student Champion
Mariella Savage

Tendon injuries are common causes of lameness in the ridden horse, and are particularly associated with strenuous exercise. Whilst the majority of these injuries require thorough diagnostic investigation and a long, controlled treatment plan, new research into laser therapy as a tool to treat tendon injuries is becoming increasingly popular, with studies showing excellent results.

 Image 1

Tendons are elastic structures which passively transfer force generated by muscles to bony attachments on the opposite side of a joint to allow movement. They are composed of tightly packed, parallel collagen fibres, which give tendons their huge tensile strength[1]. Tendinitis, or inflammation of the tendon, may be seen when these fibres are disrupted, often during the fast work undertaken by racehorses, eventers and other competition horses. Tendon injuries due to repetitive overload during exercise are more likely to be seen in the forelimb than hind limb, with the flexor tendons most commonly affected[2]. With a galloping horse placing it’s entire body weight for a moment in time on one single limb, as seen in image 1, it is clear to see the immense stress the superficial and digital flexor tendons are under during strenuous exercise, and explains the high prevalence of these injuries amongst competitive horses. Tendon injuries may also occur due to a traumatic incident involving the leg, a laceration or contusion (bruise)[3]. Cartilaginous changes within the deep digital flexor tendon in the older horse may also predispose a geriatric horse still in work to tendon injuries[4]

After a veterinarian has diagnosed a tendon injury by clinical and lameness examination as well as palpation and diagnostic imaging such as ultrasound and MRI, for many horses the treatment and rehabilitation following tendon injuries is a slow, long process.[5] Although the acute inflammatory phase seen immediately after injury as sudden lameness and a hot, swollen tendon tends to only last 1-2 weeks, the chronic remodelling phase of tendon healing involves scar tissue forming over a number of months[6]. Due to the length of this time period, it is important that horses with tendon injuries are prevented from excessively using the affected tendon by being held on box rest, with a controlled ascending exercise regime slowly introduced. With the addition of pain relief given in the form of non-steroidal anti-inflammatories, complete rest is the main treatment option available with the lesion’s healing process being monitored regularly via ultrasound[7].

Biological therapies such as Platelet rich plasma (PRP) are also frequently used to encourage tendon healing and attempt to speed up the recovery process, however despite PRP’s popularity, there is a lack of high level evidence proving the efficacy of PRP in tendon injuries[8].  Extracorporeal shockwave therapy (ESWT) is also commonly offered as a treatment option for tendon injuries including tendonitis.[9] However as with PRP, more randomised clinical trials and higher levels of evidence are needed to prove ESWT’s efficacy as a treatment, rather than just having analgesic (pain relief) properties.

Despite often guarded prognosis and variable response to different treatments, new research into laser therapy is providing an alternative approach to treating tendon injuries. Laser therapy is a source of electromagnetic radiation which penetrates deep into tissues, providing anti-inflammatory, analgesic, regenerative and draining effects, and is becoming increasingly popular as a treatment option.[10] Research into laser therapy has found it to be a non-invasive, efficient procedure which reduces recovery times of musculoskeletal injuries, and may be used to treat neurogenic pain, acute and chronic tendon/ligament injuries, muscle strains, degenerative joint disease and poor healing wounds[11]. Indeed, high power laser therapy has been used in prominent sports teams and human athletes including members of Manchester United’s football team and Tennis stars Novac Djokovic and Venus Williams for musculoskeletal problems[12]. For our equine athletes, increasing studies on horses with tendon injuries and their response to laser treatment has been published, showing excellent results. A 2015 scouting study of 150 sport horses carried out by Mathilde Pluim et al at the German equine hospital, Tierklinik Lusche, were diagnosed with tendinitis of the SDFT, DDFT, suspensory ligament and suspensory branch. These 150 horses were treated with FP4 high power laser therapy over 2 weeks, and for all four pathology groups, there was a significant improvement in lameness degree and ultrasound appearance of the injury, 4 weeks after laser therapy.  84 of the 150 horses were available for a 6 month follow up after laser treatment, and showed that 85% of this group were sound and 70% were back performing.[13]


Image 2: Pluim, M., Koene, M., Luciani, A. et al. 2015.

The ultrasound image shows an acute lesion to the superficial digital flexor tendon of an 8 year old Showjumper, at day 0 and then again at day 14. Even within this 2 week gap, you can see considerable shrinking of the SDFT tendon lesion, seen circled in both the top and bottom ultrasound images.

Although treating equine tendon injuries with laser therapy is still a relatively new and limited option in the UK, the increasing evidence for its efficacy means that without a doubt that it is likely to become a more popular and available option in the future of equine veterinary medicine.


[1] Sjaastad, O.V., O. Sand, and K Hove. ‘Physiology Of Domestic Animals’. 2nd ed. Oslo: Scandanavian Veterinary Press, 2010.

[2] Mcllwraight, C.W. ‘Tendonitis’ MSD Veterinary Manual. 2018

[3] Anderson, J. ‘Impacts of persistent injuries on athletic and performance horses’. 2016. Veterinary Business Development Limited. Vet times.

[4] Birch, H.L., Bailey, J.V.B., Bailey, A.J., Goodship, A.E. ‘Age – related changes to the molecular and cellular components of equine flexor tendons’ 1999. Equine veterinary journal. MEDLINE/PubMed (U.S. National Library of Medicine)

Aailable from: erapy?' 2003, ' ilitation.'U.S. f equine flexor tendons'necessary. with contact details of practice. Not

[5] Bromiley, M. ‘Equine Injury, Therapy and Rehabilitation’.  2007. 3rd edition. Blackwell publishing

[6] Ross, W.S., Dyson, S.J. 2003, ‘Diagnosis and Management of Lameness in the Horse’. 2003. First edn, Saunder, Philadelphia.

[7] Bromiley, M. ‘Equine Injury, Therapy and Rehabilitation’.  2007. 3rd edition. Blackwell publishing

[8] Paoloni J, De Vos RJ, Hamilton, B, Murrell, GA, Orchard, J. “Platelet-rich plasma treatment for ligament and tendon injuries”. 2011. US National Library of Medicine National Institutes of Health

[9] Yocom A.F. and Bass, L.D. “Review of the application and efficacy of extracorporeal shockwave therapy in equine tendon and ligament injuries”. 2017. Equine Veterinary Education Journal

[10] Therapy Laser X, ‘What is laser therapy?’ 2014. Available from:

[11] Therapy Laser X, ‘What is laser therapy?’2014. Available from:

[12] Pluim, M., Koene, M., Luciani, A. Duchateau, L.,Delesalle, C.‘Short and long term outcome of high power laser therapy as a treatment for tendinopathy in 150 sport horses’. Universiteit Gent, Faculteit Diergeneeskunde. Laser TLX European Veterinary Conference. 2015.

[13] Pluim, M., Koene, M., Luciani, A. Duchateau, L.,Delesalle, C.‘Short and long term outcome of high power laser therapy as a treatment for tendinopathy in 150 sport horses’. Universiteit Gent, Faculteit Diergeneeskunde. Laser TLX European Veterinary Conference. 2015.


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