Partial carpal arthrodesis in a 2-year-old alpaca.

A 2-year-old alpaca was presented for acute onset right forelimb lameness. Clinical findings included bilateral carpal valgus (more severe in the affected forelimb) and medial instability of the right radio-carpal joint. Surgical treatment consisted of radio-carpal joint arthrodesis, which is presented as a therapeutic option for severe carpal instability secondary to injury to the supporting ligamentous structures of the carpus.

Arthrographic analysis of communication between the tarsometatarsal and distal intertarsal joints of the horse.

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.

Preliminary studies on the vascular anatomy of the equine superficial digital flexor tendon.

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.

Postanesthetic equine myopathy suggestive of malignant hyperthermia. A case report.

Signs of malignant hyperthermia, including progressive increases in PaCO2, skin temperature and heart rate, and elevated serum levels of potassium, inorganic phosphate, and creatine kinase, were identified in a halothane-anesthetized horse. Treatment was discontinuing halothane administration, applying ice and cold fluids, and hyperventilating with 100% oxygen. After an initial recovery, bilateral hindlimb myopathy and pigmenturia developed. The myopathy resolved after treatment with oral dantrolene, IV fluids, and hydrocortisone. Results of caffeine-halothane challenge, using semimembranosus muscle collected 2 weeks after the episode, were considered within normal limits for horses. The intraoperative abnormalities were evidently predictive of postanesthetic myopathy but the cause in this horse remained unclear.

Use of the cobra head bone plate for distal long bone fractures in large animals. A report of four cases.

Four long bone fractures with a short distal fragment were repaired with a cobra head bone plate alone (2 cattle) or in combination with a straight, broad dynamic compression plate (2 horses). Three fractures were of the distal femur (1 horse, 2 cattle) and one was of the distal radius (1 horse). The long-term outcome of the three femoral fractures was soundness in one case and mild lameness in two. Although satisfactory bone healing progressed in the horse with the radial fracture, laminitis in the contralateral forelimb necessitated euthanasia at week 6.

Complications during treatment of traumatic disruption of the suspensory apparatus in Thoroughbred horses.

A total of 19 Thoroughbred horses were treated for traumatic disruption of the suspensory apparatus, using either external support of the injured limb, removal of fractured proximal sesamoid bone fragments, metacarpophalangeal arthrodesis, compression screw fixation of the fractured proximal sesamoid bones, application of a cast-brace attached to a transfixation pin inserted through the third metacarpal bone, or combinations thereof. Major complications during the treatment of traumatic disruption of the suspensory apparatus were infection (9 of 19 horses, 47%), large cast sores (10 of 14 treated horses, 71%), laminitis (7 of 19 horses, 37%), and orthopedic implant failure or loosening (4 of 6 treated horses, 67%), which led to euthanasia in 16 of 18 cases with complete follow-up information. Increased pain and lameness signaled the development of such complications. In 7 of 9 cases with infection confirmed by microbiologic culture, the horse had received surgical treatment; in 6 of those 7 cases, the infection involved the surgical site. Postoperative wound infection developed in 4 of 7 cases when the surgery was performed within 18 days of injury. In 3 cases, septic metacarpophalangeal arthritis developed, but it was unrelated to surgical procedures. Implant failure or loosening and infection led to euthanasia in 5 of 6 horses treated by internal fixation to stabilize the metacarpophalangeal joint. Three of 6 attempts to perform metacarpophalangeal arthrodesis by application of a bone plate to the dorsal aspect of the joint resulted in implant failure after 45 to 101 days. Major complications did not develop in 2 horses that were treated successfully.

Decalcified bone grafts in the horse.

The need for early postoperative weight bearing following fracture repair in the horse has led to investigation of various means of expediting the healing process. Bone grafting represents one means of accomplishing this, and the transplantation of autologous tissues has proven to be most useful in equine orthopedics. Acid-decalcified, frozen, allogeneic bone for grafting is easy to prepare, readily contoured, osteogenic, and elicits no obvious immune or rejection response. The most compelling reason for the use of the substance is the elimination of the need of a harvesting operation on a patient already undergoing extensive surgery for the restitution of skeletal integrity.

Effect of exogenous hyaluronic acid on joint function in experimentally induced equine osteoarthritis: dosage titration studies.

A single intra-articular injection of 20 or 40 mg of purified hyaluronic acid of rooster comb origin resulted in restoration of normal joint function in horses with experimentally induced osteoarthritis. The functional improvement, measured by pressure sensitive force plate techniques, was detectable within one week after treatment and persisted throughout a four week experimental period despite continued use of the joints. The response was dose dependent in that injection of 0 (saline), 5 or 10 mg hyaluronic acid per joint space resulted in no significant change in joint function while dosages of 20 or 40 mg produced maximum improvement.

Effect of hyaluronic acid in naturally occurring and experimentally induced osteoarthritis.

Effect of intraarticular injections of hyaluronic acid was evaluated in two groups of horses, using force plates to assess quantitatively the degree of lameness observed. In six horses, chip fractures were created surgically on the dorsomedial aspects of both radial carpal bones. After the horses were trained for 30 days, 40 mg of hyaluronic acid was injected intraarticularly into the limb showing the greater degree of lameness. Horses were worked for 2 more weeks and then were evaluated. A highly significant (P less than 0.01) increase in weight bearing on the treated limb was observed. Ten horses with clinical unilateral front limb lameness, involving a single joint, also were treated with 40 mg of hyaluronic acid. The day after the injection, the horses resumed training and were examined 2 weeks later. At that time, the horses were free from observable lameness, and this observation was corroborated by force plate data. According to their trainers, the horses' performance improved markedly after the injection and remained improved. Seemingly hyaluronic acid was beneficial when injected into the arthritic joints of these two groups of horses.