Extensor Tendon Injury
Introduction
Extensor tendon injuries frequently involve the metacarpal and metatarsal regions in horses.
Trauma is the usual cause.
When lacerations occur in the front limb, the common and lateral digital extensor tendons can be affected. In the hind limb, lacerations may involve the cranialis tibialis, long digital extensor or peroneus tertius tendon.
These injuries are often avulsion-type trauma and may be accompanied by secondary bone trauma and sequestration of the cannon bone.
Clinical Signs
These injuries do not usually cause severe lameness but they interrupt the horse's ability to protract the limb and lay the foot flat on the ground in the cranial stride.
The horse will therefore stumble and appear reluctant to extend its limbs.
There will often be a large wound on the dorsal aspect of the cannon bone.
Diagnosis
Digital palpation using sterile gloves will usually reveal the extent of the tendon laceration.
Care should be taken not to push foreign material further into the wound and to avoid soft tissues such as arteries, tendon sheaths and joints.
Radiography can be used to assess the integrity of the bony structures.
Ultrasonography can help further define the tendon injury and may identify foreign material.
Systemic assessment is critical as these horses may have lost a significant amount of blood or have other injuries and be in a state of shock.
Treatment
Routine first aid of the wound is indicated initially.
For complete extensor tendon lacerations: the optimal approach is to close the wound, reappose the tendon ends and provide support to the fetlock to prevent knuckling for at least the first 6 weeks of healing.
Many lacerations and wounds cannot be closed due to the severity of the trauma and are treated with second-intention healing.
Weight-bearing is permitted by applying splints, soft casts or resin-reinforced bandages. The main aim of these is to prevent dorsal knuckling of the fetlock.
The extensor tendon ends do not need to be sutured for a successful outcome.
Conservative management of the wound and tendon injury can result in complete return to athletic use.
Sequestra from the dorsal cannon bone may have to be removed in severe injuries.
| Extensor Tendon Injury Learning Resources | |
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 Test your knowledge using flashcard type questions |
Equine Orthopaedics and Rheumatology Q&A 11 |
References
Baxter, G. (2011) Adam and Stashak's Lameness in Horses John Wiley and Sons
Duncanson, G. (2010) Veterinary treatment for working equines CABI
Stashak, T. (2009) Equine Wound Management John Wiley and Sons
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