When the SDFT is damaged significantly, there is a thickening of the tendon, giving it a bowed appearance when the leg is viewed from the side.
This is most commonly seen in performance horses that gallop or jump, who usually strain a tendon as a result of fetlock overextension when their weight is loaded on one leg.
After the fibers are torn, the tendon hemorrhages and collects fluid (edema), creating swelling and lameness in the area as well as increasing the pressure.
The increase in pressure may damage the tendon further by destroying the cross-linking of undamaged collagen fibers and preventing the flow of blood to the area.
The middle third has a poor supply of blood, relying on the tiny vessels of the peritendon (the membrane that surrounds the tendons).
The compression may cause the area to swell once the bandage is removed, giving a "bowed" appearance.
Signs of acute tendinitis include swelling, heat, and pain when the affected area is palpated.
[1] Generally speaking, the most important aspect of long-term therapy is controlling the level of exercise.
[2] A balance must be struck between two competing ideas: For the first several months, large area turnout is discouraged, since even a small amount of running or playing could easily re-injure the weakened tendon.
An impatient trainer who rushes to bring the horse back to intense training is likely to cause re-injury of the tendon.