Summary The vascular and microvascular anatomy of normal equine superficial digital flexor tendons was studied by dissection of vinyl‐perfused specimens and by microangiography on high detail film. The presence of an extensive intratendinous vascular latticework was confirmed, and a ‘nutrient artery’ described closely associated with the accessory ligament of the superficial digital flexor tendon (proximal check ligament). Circumferential stripping of the paratenon from the tendon to eliminate afferent vessels was performed bilaterally in three horses and unilaterally in a fourth, followed by a treadmill training regimen. No resulting intratendinous lesions could be documented on gross post mortem and histological examination at three, 10, or 35 days post operatively. There was mild paratendinous proliferation in all instances. In one horse, four intratendinous ligatures were placed within the medial and lateral borders of the contralateral tendon to isolate further from its blood supply a 10 cm segment. Gross lesions at 35 days post operatively included a marked paratendinous response involving the entire 10 cm segment, and a darkened, soft focus within the core of the tendon. Histopathology and electron microscopy demonstrated focal degeneration. It was concluded that the blood supply of the normal equine superficial digital flexor tendon is primarily intratendinous, rather than paratendinous as previously thought. The lesions in one horse similar to those in naturally occurring tendinitis supported a vascular aetiology of the disease, and set the groundwork for studies aimed at the development of a clinically relevant tendinitis model.

The intra-articular anatomy of 103 equine tarsi was studied by contrast radiography with image intensification and computerized tomography. There was communication between the tarsometatarsal and distal intertarsal joints in 21 of 55 (38%) interpretable tarsometatarsal arthrograms, and in 11 of 48 (23%) interpretable distal intertarsal arthrograms. The difference was not significant. The volume of contrast agent and the pressure of injection did not correlate with communication. Forced injection caused subcutaneous leakage of contrast medium but not communication. Communication occurred via the tarsal canal and the space between the third and the combined first and second tarsal bones. Injection of the distal intertarsal joint from the dorsomedial aspect of the limb, distal to the palpable distal border of the medial branch of the tendon of the tibialis cranialis muscle and between the central, third, and combined first and second tarsal bones, provided reliable access except in the presence of severe periosteal proliferations.

The clinical signs, diagnosis, surgical treatment, and postoperative results in 8 horses with comminuted or open fractures of the splint bone are described. Surgical therapy was chosen to hasten the convalescent period, prevent large callus formation, improve cosmetic appearance, and, in open fractures, for aggressive wound management. Four horses used for nonracing purposes had full recovery following surgery. Two of four racehorses had residual lameness after surgery. Three of four racehorses eventually raced with decreased performance.