Guide to the Superficial Digital Flexor Tendon

Your horse’s lower legs are made up of a complex and fascinating system of tendons, ligaments and bones. The superficial digital flexor tendon (SDFT) is one of the major tendons in the horse’s lower leg. This blog article outlines what the SDFT is, how it works and why it’s important to the horse’s movement.

Where is the Superficial Digital Flexor Tendon?

The SDFT is located to the back of the lower leg. It runs from its parent muscle – the superficial digital flexor muscle, which is located behind the radius and ulnar (in the foreleg) or the tibia (in the hind leg) – down to the fetlock. Take a look at the diagram below for more detail:

What is the purpose of the superficial digital flexor tendon?

Tendons in the lower limb – including the SDFT – transfer the energy generated by the parent muscles down to the lower leg. It is important to remember that the parent muscle and its associated tendon work as a unit to make the lower leg move. 

The SDFT is a flexor tendon, meaning it helps the leg to “flex” or close the joints. The SDFT, along with the deep digital flexor tendon (DDFT) help take the load as the leg bears its full load. The digital flexor tendons, along with the suspensory ligament, also support the fetlock joint during the weight-bearing phase of each stride. 

The SDFT also helps to conserve energy for its parent muscle – the superficial digital flexor muscle. As the SDFT is stretched, it stores energy. When that weight is released, the SDFT recoils. This releases the energy, which helps to conserve energy for the parent muscle. 

How Can SDFT Injuries Occur?

The SDFT is a hardworking, yet vulnerable tendon. It is designed to stretch, store energy and absorb concussive forces to a degree. This all places a lot pressure on the SDFT, which is also vulnerable due to its situation at the back of the leg. The superficial digital flexor tendon is one of the most commonly injured tendons. 

One way in which the SDFT can be damaged is through overextension of the fetlock joint. As the horse bears its full weight on one leg – during canter or gallop, for example – the SDFT, DDFT and suspensory ligament help to support the fetlock joint. Harsh, sudden acceleration or braking can cause the fetlock joint to extend to the point where it actually makes contact with the ground. Racehorses and reining horses are particularly vulnerable to this type of hyper-extension. 

As we have already mentioned, the SDFT, DDFT and suspensory ligament all help to support the fetlock as the horse bears weight. If the DDFT cannot take its share of the weight – due to rutted, uneven ground, for example – the SDFT and suspensory ligament have to take a greater share of the burden. This puts additional strain on those areas, which can then lead to damage. 

Another significant risk to the SDFT is strike and overreach injuries. The foreleg is especially vulnerable as it can be struck by the hind hoof as the horse brings its legs forward. The SDFT can also be damaged if the horse leaves a leg behind over a jump or if it is brushed or struck by the opposite leg. 

More broadly speaking, the chance of injury occurring to the SDFT and other significant tendons in the lower leg is increased by various factors.

Other Factors that Increase the Chance of Injury to the Superficial Digital Flexor Tendon:

• Inadequate warm up before exercise – cold tendons are less able to stretch safely
• Excessive heat – boots and bandages can insulate the legs and prevent heat from leaving the soft tissues. Removing boots or bandages immediately after exercise and icing the legs will help take the heat out of the leg quickly.
• Working on hard and / or uneven ground, or very soft, heavy ground
• Excessive weight bearing – overweight horses or riders that are too heavy places additional strain on the SDFT and other tendons
• Micro trauma or micro-tears – The problems caused by micro trauma are often seen in older competition horses. This is as a result of repeated micro tears over many years. 

The Importance of Keeping Your Horse’s Legs Cool

This is why it is so important to always remove boots after exercise and ice your horse’s legs effectively. Icing aids recovery and helps the horse’s body repair the micro trauma that occurs during exercise. By helping the horse to recover properly after every exercise session, we are helping to reduce the chance of injuries later on. 

There is no way of preventing every single injury. However, as riders we can help reduce the chance of preventable damage occurring by looking after our horses’ legs. Paying attention to ground conditions, monitoring fatigue and fitness levels and warming up and cooling down effectively all help to keep their legs healthy. 

Minimise Heat Build Up During Exercise with The Exoskeleton

The Exoskeleton exercise boot is designed to minimise heat build up during exercise, whilst providing unparalleled strike and impact protection. The external skeleton has been designed to protect the most vulnerable areas, including the SDFT. Meanwhile, strategically placed vents help to force air across the back of the leg as your horse moves. The Exoskeleton is also lightweight and comfortable for the horse, as the material is soft without holding water or sweat. 

Give your horse the very best in leg protection with the Exoskeleton.

Cool Those Legs Quickly After Exercise with Cryochaps Ice Boots

Immediately after exercise, remove your horse’s exercise boots and swap them for Cryochaps ice boots. Our ice boots are designed to cool your horse’s legs quickly after exercise. Cryochaps K2F ice boots provide full knee-to-fetlock coverage, and the neoprene compression sleeve helps to provide maximum cold transfer. 

Enhance your horse’s post-exercise care with Cryochaps K2F ice boots.