Managing our horses ongoing health can be a challenge. Often understanding specific terminology can be an important step in helping to reduce confusion and lower anxiety-levels when a new injury does occur.
One equine injury which is regularly mentioned is “DDFT” or “DTFS” injuries.
In this article we look at what the Digital Flexor Tendon Sheath is, how they become injured in the first place, what diagnosis is carried out and what treatments are offered to horses with diagnosed DDFT injuries.
What is the Digital Flexor Tendon Sheath?
The Digital Flexor Tendon Sheath, DFTS, is located in the fetlock region of your horse, running down the lower third of the cannon bone and ending near the navicular bursa. This thin-walled structure contains both the Superficial Digital Flexor Tendon (SDFT) and the Deep Digital Flexor Tendon (DDFT).
It’s purpose is to help lubricate and stabilise the tendons passage through the highly mobile fetlock area and the horses pastern region.
As a horse propels itself towards a jump it shifts its weight backwards and launches it’s body into the air. The tendons within this process act as ‘springs’ which store energy within each stride - as such a fully grown horse has very long tendons, normally more than 50cm long.
The superficial digital flexor tendon has most of this ‘spring-like’ function and the deep digital flexor tendon acts more of a supportive role for the horses feet.
Unfortunately, when a horse damages this tendon - action is required!
What is a DDFT injury?
Most DDFT injuries affect the forelimb and will normally be found in the pastern region where the back of the horses legs touch the ground when bearing their full weight. In most scenarios the horse will become lame.
Spontaneous injuries through overstraining of the tendon are rare outside of the sports horse industry however. As such, most DFTS injuries are often associated with long term degeneration of the tendon itself as opposed to being created via trauma.
Sports horses, simply by the nature of their activities, are most at risk as they exert additional strain on their tendons through jumping or stretching in their stride and as with any athlete can experience muscle tears and strains. Tendon and ligament strains comprise of over 40% of sports horse injuries, an indication of how common they are within certain sports and particularly in high-speed sports such as barrel racing, showjumping, polo and 3-day eventing.
If a horse has suffered an injury to their digital flexor tendon it will normally effect the internal parts of the tendon or the outer surface of the tendon itself.
The horse will likely show signs of acute or chronic lameness, with the first visible sign being swelling and inflammation within the effected limb. If the sheath wall has been torn then this swelling may be asymmetric in shape and is sometimes referred to as Asymmetric Windgalls.
Many owners will detect an issue by carefully feeling their horses leg and establishing whether an increase in heat is present; often paired with establishing whether there is an increase in the digital pulse.
In some cases the horse will show signs of pain and soreness and reduce levels of mobility within the limb.
When the DFTS is inflamed this would normally indicate higher levels of pain and lameness, the greater the swelling the greater the cause for concern.
All DDFT injuries are serious and require a carefully planned rehabilitation process if they are to make a full recovery.
Diagnosing a DDFT injury
In most circumstances, however experienced you are at caring for your horse, obtaining a professional diagnosis of a DDFT injury is important.
The best chance of a definitive diagnosis is to have the horse inspected after 7-10 days following the injury - this allows the initial inflammatory response to subside slightly.
Concluding the exact diagnosis can be tricky but with many techniques now available within the equine community there are many options to call upon.
In many cases the first diagnosis technique a professional will carry out is a localised nerve, joint, tendon or navicular “block”. These are injections of local anaesthetic which are injected directly into the joint or tendon canal and are carried out so the vet can accurately determine the exact location of the pain. Nerve blocks will tell your vet whether the horse is sore and in pain but will not help diagnose whether the problem is the tendon, navicular bone or another structure.
Once it has been established where the pain is coming from low-field MRI scans are commonly used. MRI scanning represents a useful diagnostic tool for establishing DDFT injuries and although not cheap do represent a valuable tool in establishing the exact location of the injury with a view to providing the best rehabilitation plan.
Tenoscopy is a modern technique used within equine care in which small incisions in the skin are made to allow for careful visualisation (and cleaning) of the tendon injury itself. Small cameras look inside the tendon sheath, similar to arthroscopy.
Thermography, or thermal imaging, is becoming a widely adopted tool for diagnosis of tendon, ligament or muscles injuries and this technology can be particularly useful at establishing DDFT injuries.
Infection within the digital tendon sheath can be catastrophic for your horse. To avoid complications with infections it is important to inspect the horse meticulously for any signs of a wound.
Treatment from a DDFT injury
Tendons are similar to muscles and ligaments, they require time to heal through a period of rest and rehabilitation. This can be an extremely slow process and in some cases will require up to 12-months of rest. This allows the tendons to effectively heal and provides the horse with the best chance of a full recovery.
Reducing the inflammation created by the DDFT injury is key. Reducing inflammation will help reduce pain levels and allow the healing process to take place.
Bute and other non steroidal anti inflammatory medications (NSAIDS) will commonly be prescribed to aid a reduction in inflammation and provide a level of pain relief.
Many owners will include cold therapy techniques to aid the reduction in inflammation including cold-hosing two or three times day to ensure the leg stays cool. Ice-boots are also popular for short periods of use specially developed to reduce the temperature of the horses legs. Traditional magnetic boots and wraps should be avoided when treating DDFT injuries, although magnets themselves do not create heat the reaction of the cells when placed against magnetic fields does increase heat and can provide further complications.
Providing a non-invasive pain relief option, Advanced Magnetic Technology represents a valuable tool in supporting the horses reduction in inflammation and unlike with medications these forms of therapy can be used long term without negative side-effects. Their unique approach to magnetism creates no heat and as such they are ideal when using on horse with any muscle, tendon or ligament issue, including DDFT.
Horse owners traditionally wrap bandages around their horses injured leg to help immobilise the limb and prevent over exertion in the affected tendons.
As the horse is recovering many owners look at whether any orthopaedic shoeing changes are required to support the horses recovery process.
Further therapies such as stem cell therapy and platelet-rich plasma therapy are being adopted more commonly to improve the healing process of the tendon themselves and are developed to ensure the tissues heal stronger. Hyaluronic acid and corticosteroids can also be used to help treat inflammation within the sheath. Other therapies such as shock wave therapy also achieve results.
Surgery after a DDFT injury is extremely rare but if the tendon is badly lacerated or infection and bacteria has occurred then surgery under general anaesthesia can be carried out. In rare cases the SDFT is cut to allow the muscle and tendon to extend further and reducing the risk of re-injury.
Recovering after a DDFT injury
As we mention above, time is key when recovering from a DDFT injury.
If the injury is a mild strain then you could be lucky and see your horse make a full recovery within 6-8 weeks, however, anything more than a mild strain can lead to over a year of box rest and and extensive rehabilitation process.
Doing too much too soon can set you back months and in some cases prevent healing altogether. Once a horses tendons have been subjected to an injury they will be more susceptible to injury in the future.
Alongside a period of rest and recuperation many owners now look at complementary therapies such as hydrotherapy and physiotherapy to use alongside the horse recovery plan. These techniques look to provide the horse with light and controlled exercises. Many of these therapies can be discussed with your vet who should offer sound advise on what the pros and cons of each therapy may be.
Controlled exercise program following DDFT recovery
Due to the length of the recovery process in most DDFT injuries, many horse owners will look at designing a reintroduction to exercise program aimed at getting their horse back to full fitness with a step-by-step approach.
Many would agree that slowly reintroducing exercise is an important aspect of recuperation and in most cases will be throughly discussed with your vet.
In most cases the horse will begin light exercise with in-hand walking with gradual increases every 2-3 weeks for a period of 3-4 months.
Controlling their exercise helps the tendons fibres to recovery gradually and ultimately result in increased strength and mobility of the damaged tendon. Many will use ultrasound technology throughout this process to determine the success of the healing process and with that knowledge be confident in reintroducing trot work.
In severe cases it may be that your horse will never fully recover - but with modern techniques and technologies as we mention above this is very rare and in the majority of cases your horse should be able to return back to normal work.
If your horse has developed a DDFT injury then you have access to a whole plethora of treatments and your vet will be well experienced in treating such a condition and recommending the most appropriate for your horse. Be prepared to allow your horse plenty of recovery time and look at investing in complementary therapies which can support your horses natural recovery process.