The digital extensor tendons are less well-known than their biological counterparts, the SDFT and DDFT. Where the flexor tendons help flex the lower (distal) limbs and bring them back, the extensor tendons allow their parent muscles to bring the lower limb forwards. This guide aims to outline the basic anatomy and functions of the equine digital extensor tendons.
Digital Extensor Tendons in the Thoracic Limb (Front leg)
Common Digital Extensor Tendon
The common digital extensor tendon originates from the common digital extensor muscle (located above the knee or carpus). The tendon runs down the front of the leg into the distal phalanx (pedal bone). The common digital extensor tendon extends the carpus (knee) and lower leg, bringing the knee and lower leg up and forward.
Lateral Digital Extensor Tendon
The lateral digital extensor tendon originates from the lateral digital extensor muscle (again located just above the knee). It runs down the side of the leg into the proximal phalanx (long pastern). The lateral digital extensor tendon helps to extend the carpus (knee) and metacarpophalangeal joint (fetlock).
Both of these tendons are protected by synovial sheaths (tendon sheaths). Unlike the extensor tendons in the hindleg, these tendons do not join up.
Digital Extensor Tendons in the Pelvic Limb (Hind Leg)
Long Digital Extensor Tendon
The long digital extensor tendon originates from the long digital extensor muscle (which sits just above the hock)and runs down the front of the hindleg, joining the lateral digital extensor tendon at the long pastern and continuing down to the pedal bone. It extends the lower hind leg and flexes the hock, bringing the lower hind leg up and forward.
Lateral Digital Extensor Tendon
The lateral digital extensor tendon originates from the lateral digital extensor muscle (above the hock) and runs down the side of the hindleg to the proximal phalanx (long pastern), where it joins up with the long digital extensor tendon. It aids the long digital extensor tendon in extending the digit and hock.
Again, these tendons are protected by synovial sheaths as they pass over joints.
Injury to the Digital Extensor Tendons
Whilst injury to the digital extensor tendons is less common than injury to the SDFT, it can occur. The symptoms are similar to the symptoms of injury in other tendons: heat, swelling, pain, lameness, reduction in range of motion, change in ridden behaviour or gait and poor performance. Tripping or excessive flicking of the toe are also signs of an injury to the digital extensor tendon.
Causes of Injury
Again, the causes of injury to the digital extensor tendons are similar to other tendons in the lower leg. Strains, overflexion of the limb, working on hard, rutted, uneven ground, twisting and turning at speed, overworking and repetitive movements can all contribute to injury. Often, tendon injuries are the result of repetitive low-grade strains and overloads rather than a single major trauma.
Open or puncture wounds can also affect the digital extensor tendons, and this can be particularly serious if it results in an infection of the tendon sheath.
Treatment for injury to the tendons usually consists of box rest, icing (especially for the first 24-48 hours to reduce inflammation) and controlled return to exercise. Your vet may also administer painkillers and / or anti-inflammatories. You may also be advised to bandage your horse’s legs during recovery to protect the fetlock and foot in the event that the horse trips.
Cryochaps Ice Boots
Icing your horse’s legs after exercise or injury may aid recovery, reduce inflammation and help to minimise pain. Designed to cover all the major soft tissues in the lower leg, Cryochaps ice boots for horses are ideal for all disciplines. Simply keep them in the freezer, then wrap, strap and leave on for 10-15 minutes. You can even take your Cryochaps with you to competitions and arena hires with our handy cool bag!