A bowed tendon is strictly speaking in fact a strain of the tendon. Bowed tendons commonly occur in racehorses, but can occur in any breed in any kind of work. They are usually due to wear-and-tear injuries and initially signs may be difficult to spot. However, the earlier they can be detected the better as early diagnosis improves the prognosis considerably.
The damage in these over-strain injuries is to the superficial digital flexor tendon at the back of the cannon region. The most obvious sign of the problem is a curved, “bowed out” swelling along the back of the leg between the knee and the fetlock. On palpation you can expect to feel some heat, and if pressure is applied to the tendon when the limb is lifted there is likely to be pain.
This requires your vet to perform an ultrasound scan of the tendon to a) confirm the diagnosis and b) assess the extent of the damage.
Horses with a bowed tendon are usually put on box rest for a short period before a controlled exercise program is introduced to bring them back into low-level work. Cold-hosing, bandaging and anti-inflammatory drugs are often required in the acute phase to reduce inflammation. Various regenerative treatments, like laser therapy and stem-cell treatment are also available, but the science proving their efficacy is still lacking for bowed tendons.
Prognosis for return to the previous level of work is fairly variable after a bowed tendon. It is estimated that around 50% of show jumpers will return to their previous level of work. However, because the tendon fibres that have been injured over time are replaced with scar tissue, which is less elastic, the risk of re-injury is quite high.