Frequency distributions of 174 fractures of the distal condyles of the third metacarpal and metatarsal bones in 167 Thoroughbred racehorses (1999–2009)

Reasons for performing study: Although fractures of the metacarpal and metatarsal condyles are the most common long‐bone fractures of Thoroughbred horses in training, limited data on variations in morphology and incidence have been published. Additionally, grouped analyses of previous studies from the UK and USA would permit comparison between study groups and the creation of a substantial pool of international data. Methods: Retrospective analysis of case records of horses with fractures of the distal condyles of third metacarpal/metatarsal bones seen over the last 10 years at Newmarket Equine Hospital. The current series was compared with a prior series from the UK; pooled analyses of these, and series from the USA were also compared. Results: One hundred and seventy‐four fractures were identified in 167 racehorses. The current series contained a significantly lower proportion of medial condylar fractures than in a similar population 17 years earlier. Fractures that originated more abaxially tended to be shorter, and a significant proportion of lateral condylar fractures arose outside of the condylar groove. There was also some apparent seasonality of fractures of the lateral condyles in 2‐year‐old horses, but not so in older horses or those with medial condylar fractures. Conclusions and potential relevance: A substantial portion (approximately 50%) of fractures in the present series cannot be explained by unifying theories of aetiopathogenesis, which suggest that fractures usually arise within the condylar groove, as a focus of cumulative fatigue and failure of adaptation of bone. A separate aetiopathogenesis may be responsible for a proportion of condylar fractures encountered in racehorses, and further work is required to elucidate this. Changes in the number of medial condylar fractures encountered may reflect the introduction of artificial racing and training surfaces, and also may reflect changes in the age demographic of horses racing in the UK since the introduction of year‐round ‘all‐weather’ racing.     

Surgical repair of skull fractures in four horses using cuttable bone plates.

Three horses with severely comminuted, open facial bone fractures and one horse with a comminuted, open orbital rim fracture were referred for treatment. Severe facial bone asymmetry and epistaxis were apparent in all cases and subcutaneous emphysema was present in two, however physical and neurological examinations were otherwise normal. Radiography and endoscopy were of some use in assessing the degree of damage, although the true extent of the damage was more apparent at surgery. Surgical reduction of the fractures was recommended to maximise cosmetic and functional outcome. After surgical debridement and reduction of the fractures the bone fragments remained unstable and were not amenable to stabilisation with interfragmentary wires alone, so 2 mm cuttable bone plates were used to maintain fracture alignment. Screw migration occurred in three horses and in one of these horses the plate had to be removed. Other complications were minor and in all horses the fractures healed with good cosmetic and functional outcome. The use of cuttable bone plates should be considered as a reasonable alternative to inter-fragmentary wiring for unstable, comminuted fractures of the facial bones, even where fractures are open.     

Computed tomography of proximal metatarsal and concurrent third tarsal bone fractures in a Thoroughbred racehorse

A 2‐year‐old Thoroughbred filly presented to the William R. Pritchard Veterinary Medical Teaching Hospital at the University of California at Davis for whole body nuclear scintigraphic evaluation after an acute onset of nonweightbearing right hindlimb lameness post race. The use of computed tomography (CT) enabled visualisation of additional pathology that was not initially appreciable using combined imaging modalities of nuclear scintigraphy and digital radiography, which ultimately altered the selected course of treatment. Computed tomography in horses with fractures of the cuboidal bones of the hock can provide valuable additional information regarding fracture configuration and radiographically occult pathology, which may help to guide clinical decisions about treatment.     

Surgical salvage from comminuted metatarsal fracture using a weight-bearing pin-putty apparatus in a dog

Comminuted metatarsal fractures in a dog were treated using intramedullary pins externally connected and stabilized by epoxy resin putty and application of a fibreglass cast. Two weeks later the cast was removed. After further 2 weeks application of a Robert-Jones bandage the dog could stand and walk with the pin-putty apparatus in position. The pin-putty apparatus was removed 3 months postoperatively, and the dog resumed normal activity. This fixation method could be an easy, economical and effective alternative treatment for managing comminuted fractures of the metatarsal and possibly metacarpal bones in selected cases.     

Standing repair of a proximal,incomplete, articular fracture of the third metatarsal bone

A 5-year-old National Hunt Thoroughbred mare presented with sudden onset left hindlimb lameness after race training on the gallops. Clinical examination revealed a marked painful reaction over the proximal metatarsal region but no other obvious abnormalities were detected. Survey radiographs at the yard did not reveal any abnormalities. Nuclear scintigraphic examination 3 days after injury revealed focal marked increased radiopharmaceutical uptake in the proximal metatarsal region. Subsequent radiography revealed an incomplete, articular fracture of the proximal left third metatarsal bone. Repair of the fracture using 3 × 4.5 mm cortical screws placed in lag fashion was performed under standing sedation following perineural analgesia. Follow-up radiographs demonstrated progressive healing of the fracture. The mare returned to race training 8 months after the fracture was repaired and raced successfully 12 months post injury.     

Diffuse osteomyelitis of the fourth metacarpal bone in a horse caused by Clostridium perfringens

Osteomyelitis in adult horses, often associated with trauma or iatrogenic infection following surgery, usually presents as a focal area of infected bone. Diffuse osteomyelitis, affecting both the cortex and medulla, along the full length of a bone is encountered less frequently and treatment of such infections is not well reported in horses. The 2-year-old Warmblood mare in this case was diagnosed with diffuse osteomyelitis affecting the 4th metacarpal bone with concurrent unicortical fracture of the third metacarpal bone following traumatic injury. Computed tomography (CT) aided diagnosis in this case, providing critical additional detail to that obtained with radiography and ultrasound. This case highlights the value of CT in the diagnosis of diffuse osteomyelitis. This is the first reported case of diffuse osteomyelitis caused by Clostridium perfringens in horses. Successful treatment in this case consisted of surgical debridement of the associated abscess, followed by systemic and locoregional antimicrobial therapies.     

Diagnosis and management of proximal sesamoid bone fractures in the horse

Fractures of the proximal sesamoid bones (PSBs) range in severity from simple to complex and comminuted and can be articular or nonarticular. The majority of PSB fractures are diagnosed in racehorses, but PSB fractures, especially simple ones, do occur in sport horses undertaking various disciplines. For simple apical, basilar and abaxial articular PSB fractures, surgical removal via arthroscopy carries the best prognosis for return to athletic performance. Removal of apical and abaxial PSB fractures generally result in a favourable prognosis for return to racing but are dependent on the amount of suspensory ligament injury. Removal of basilar PSB fracture fragments results in a less favourable or fair prognosis for return to racing. Mid‐body PSB fractures typically require (lag screw) surgical fixation preferably with arthroscopic guidance and carry a fair to guarded prognosis for return to racing.     

Management of fractures in endurance horses

This paper provides relevant information for veterinarians responsible for treatment of endurance horses, including a retrospective study of fractures in endurance horses presenting to one referral hospital and to treatment clinics at 3 different race venues. Treatment and case outcome were also noted. The information presented provides clinicians working with high level endurance horses increased awareness of common sites of fractures, of prefracture stress related bone injury within this population of athletes and guidelines in order to manage them more effectively. The most common fractures involve the metacarpo‐(tarso‐)phalangeal joint. Most distal limb fractures can be diagnosed radiographically, but magnetic resonance imaging or scintigraphy may be required in some cases.     

Surgical management of complete diaphyseal third metacarpal and metatarsal bone fractures: Clinical outcome in 10 mature horses and 11 foals

Reasons for performing study: Osteosynthesis of third metacarpal (McIII) and third metatarsal (MtIII) bone fractures in horses is a surgical challenge and complications surrounding the repair are common. Retrospective studies evaluating surgical repair, complications and outcome are necessary to increase knowledge and improve success of long bone fracture repair in the horse. Objectives: To evaluate clinical findings, surgical repair, post operative complications and outcome of 10 mature horses and 11 foals with McIII or MtIII fractures that were treated with open reduction and internal fixation (ORIF). Methods: Medical records were reviewed and follow‐up information obtained by means of radiographs and/or telephone questionnaire. Results: Survival was achieved in 62% of the horses (3 mature/10 foals). On long‐term evaluation (>6 months) 11 horses (2 mature/9 foals) were fit for their intended activity, one mature horse had a chronic low grade lameness, and one foal was lost to follow‐up because it was sold. The main fracture types were simple transverse (33.3%) or simple oblique (28.6%) and 71.4% of the fractures were open, 3 Type I (one mature/2 foals) and 12 type II (7 mature/5 foals). The preoperative assessment revealed inadequate emergency treatment in 10 horses (5 mature/5 foals; 47.6%). Survival rate of horses with open fractures was 12.5% (1/8) in mature and 85.7% (6/7) in foals. Post operative incisional infection (4 mature, 3 foals) was only managed successfully in 2 foals. Fracture instability related to inadequate fracture fixation technique occurred in 4 horses (all mature) and was always associated with unsuccessful outcome. Conclusions: Age, bodyweight and infection are strongly associated with outcome in treatment of complete McIII/MtIII fractures. Clinical relevance: Rigid fixation using plates and screws can be successful in treatment of closed or open, complete diaphyseal McIII/MtIII fractures in mature horses and foals. Instable fixation, infection and a bodyweight >320 kg are major risk factors for unsuccessful outcome.     

Deep digital flexor tendon rupture in two horses: A potential complication of comminuted second phalangeal fractures

This case report describes the history, clinical findings, treatment and outcome of 2 horses with damage and eventual rupture of the deep digital flexor tendon as a result of a comminuted second phalangeal fracture. The rupture of the deep digital flexor tendon complicated the treatment and in one horse contributed to its eventual euthanasia. The athletic outcome was limited in the second case and the lack of palmar soft tissue support likely had a significant effect on the stability and biomechanics of the repair.     

Treatment of incisive bone fracture in a horse using an acrylic splint

A ventrally displaced incisive bone fracture was diagnosed in a 3-year-old Andalusian stallion. Symptoms included swelling of the lips, dysphagia and ptyalism. External manipulation revealed pain and crepitus in the gingival region of the rostral maxilla. An intraoral examination revealed upper gingival haematomas, misalignment and malocclusion of the incisors (prognathism). A radiograph of the rostral maxilla confirmed ventrally displaced bilateral fractures of the incisive portion of the maxilla rostral to the canine teeth (Triadan 104/204). The fracture was reduced under general anaesthesia. A methylmethacrylate intraoral splint was used to stabilise the fracture. Post operative radiographs confirmed the fracture reduction. Post operative clinical control confirmed the correct position of the splint. No complications were encountered in the post operative period and good stabilisation was obtained. The splint was removed 60 days post operatively. The use of an acrylic intraoral splint successfully stabilised a bilateral, ventrally displaced incisive bone fracture. Normal occlusion was obtained. The use of an acrylic splint may represent a relatively simple, inexpensive and noninvasive technique for the repair of incisive bone fractures rostral to canine teeth in horses.     

Navicular bone fractures in the horse

Avulsion fractures from the distal border of the navicular bone are relatively common, but normally of little clinical significance. Other fractures are uncommon and have a poor prognosis. Surgical fixation of parasagittal fractures (lag screw) is technically quite difficult, but potentially improves the prognosis for return to work to about 80%. If surgical fixation is not possible, then farriery to raise the heels of the foot may be of benefit.     

Surgical repair of radial carpal bone fractures in two racehorses

A 3-year-old Standardbred gelding (Case 1) and a 2-year-old Thoroughbred gelding (Case 2) were referred for surgical evaluation of a left radial carpal bone (RCB) fracture, sustained during training. Clinical findings at the time of initial examination included a palpable effusion within the left middle carpal joint in both horses and marked signs of pain and reduced range of motion on flexion of the affected carpus. In both horses, the RCB fracture was evident on the following radiographic views of the carpus: dorsolateral–palmaromedial oblique (30° off lateromedial) and flexed lateromedial. An additional loose wedge-shaped osteochondral fragment at the proximal articular surface of the RCB could be seen in Case 2. Both horses underwent surgical reduction and repair of the fracture between 1 and 2 days following the initial injury, which consisted of arthroscopic removal of any intra-articular osteochondral fragments, and arthroscopic assisted-interfragmentary compression via a standard dorsomedial and dorsolateral approach to the antebrachiocarpal joint (ACJ) and middle carpal joints (MCJ). The two horses returned to function as racehorses, 6 months (Case 1) and 16 months (Case 2) after surgery. The RCB is a relatively uncommon site for large carpal fractures in horses. The clinical presentation and findings from this report were similar to that of third carpal bone (C3) slab fractures, confirming that surgical repair is indicated in selected cases of RCB fractures.     

Destructive lesions of the proximal sesamoid bones as a complication of dorsal metatarsal artery catheterization in three horses

OBJECTIVE: To describe focal destructive lesions of the proximal sesamoid bones (PSBs) as a complication of dorsal metatarsal artery catheterization performed for direct blood pressure monitoring during equine general anesthesia. STUDY DESIGN: Retrospective study. ANIMALS: Three client-owned horses. METHODS: A dorsal metatarsal artery was catheterized in each of 3 horses for direct blood pressure monitoring during anesthesia. Radiography, ultrasonography, synoviocentesis, and arthroscopy were used to diagnose postoperative lameness that occurred in the limb used for blood pressure monitoring. RESULTS: Horses developed severe lameness, localized to the fetlock region of the catheterized limb within 21 days of surgery. Antibiotic therapy was administered. Surgical debridement was possible in 1 horse. Two horses that had lesions that were inaccessible, failed to respond to medical management and were euthanatized. The 3rd horse that had surgical debridement of affected bone, survived. Changes in hospital protocol, by improving aseptic technique during catheter insertion and use of new manometer tubing and heparinized saline for each arterial catheter inserted in the dorsal metatarsal artery, have eliminated this complication. CONCLUSIONS: Diagnosis and treatment of destructive lesions of the PSB were difficult. Strict aseptic technique should be followed during insertion of arterial catheters. CLINICAL RELEVANCE: Focal destructive lesions of the PSB subsequent to dorsal metatarsal arterial catheterization is a rare but serious complication of equine anesthesia.     

Medial condylar fractures of the third metatarsal bone in horses

Fifteen longitudinal fractures involving the medial condyle of the third metatarsal bone were diagnosed in racing Thoroughbreds and Standardbreds. Twelve were repaired surgically with lag screws placed through stab incisions. Two of the horses suffered catastrophic fracture of the third metatarsal bone during recovery from anesthesia, and 3 more sustained complete fractures within 4 days of the repair. Of 3 horses with fractures treated without surgery, 2 healed without complication. Preoperative radiography did not demonstrate a nonlongitudinal fracture component in any of the horses that sustained complete fractures. The complete fractures were uniformly "Y" shaped. Horses in which the fractures healed had a good prognosis for return to racing.     

Quantitative evaluation of subchondral bone injury of the plantaro‐lateral condyles of the third metatarsal bone in Thoroughbred horses identified using nuclear scintigraphy: 48 cases

Reasons for performing study: Increased radio‐isotope uptake (IRU) in the subchondral bone of the plantaro‐lateral condyle of the third metatarsus (MTIII) is a commonly reported scintigraphic finding and potential cause of lameness in UK Thoroughbred racehorses in training and has not been fully documented. Objectives: To characterise lameness attributable to IRU of the subchondral bone of MTIII, compare the scintigraphic findings of these horses with a normal population and evaluate the use of scintigraphy as an indicator of prognosis. Hypothesis: IRU will be in significantly higher in horses with subchondral bone injury and will be related to prognosis and future racing performance. Methods: Data were analysed from 48 horses in which subchondral bone injury of the plantaro‐lateral condyle of MTIII had been diagnosed using nuclear scintigraphy and that met the inclusion criteria. Data recorded included age, sex, trainer, racing discipline, lameness assessment, treatment regimes, radiographic and scintigraphic findings, response to diagnostic analgesia where performed and racing performance pre‐ and post diagnosis. Region of interest (ROI) counts were obtained for the plantar condyle and the mid diaphysis from the latero‐medial view, the ratio calculated and then compared with a control group of clinically unaffected horses. Results: The mean condyle mid‐diaphysis ROI ratio was significantly (P<0.001) higher in the affected population and with positively correlation (P = 0.024) with the level of lameness. The presence of radiographic findings had no significant effect on the ROI ratio. Conclusion: Subchondral bone injury of the plantar lateral condyles of MTIII is a significant cause of lameness in UK Thoroughbred racehorses. Nuclear scintigraphy is a useful diagnostic imaging modality in the detection of affected horses but is a poor indicator of prognosis for the condition. Potential relevance: Better understanding of the clinical manifestations, diagnosis of and prognosis for subchondral bone injury will benefit the Thoroughbred industry in the UK.     

Computed tomographic diagnosis of incomplete palmar cortical (fatigue) fracture of the third metacarpal bone in two young adult endurance horses

Two young adult endurance horses were presented for investigation of sudden-onset forelimb lameness during competition. Clinical examination revealed a severe forelimb lameness and pain on palpation of the proximal palmar metacarpal area. Initial radiographic survey of the affected forelimb was unremarkable in both cases. A week of box rest resulted in only a mild improvement in the lameness. A second radiographic examination did not reveal any significant abnormalities. In both cases, scintigraphic examination was suggested, but was declined by the owner, and the lameness had significantly improved after local infiltration of 3 mL of anaesthetic solution in the proximal suspensory region. Radiographic and ultrasonographic examinations of the carpus and proximal suspensory region were unremarkable in Case 2. Case 1 had increased thickness of the medial lobe of the proximal aspect of the suspensory ligament. A computed tomographic examination was performed and an incomplete longitudinal (fatigue) fracture of the proximal third metacarpal bone was detected. After 8 months of box rest and rehabilitation, re-examination revealed resolution of the lameness in both cases. Advanced diagnostic imaging should be considered in young endurance horses with severe lameness during competition or training, in which radiographic and ultrasonographic examinations are unremarkable or do not explain the severity of the lameness. Computed tomography imaging is considered a useful diagnostic imaging technique to detect incomplete longitudinal palmar metacarpal cortical (fatigue) fractures due to its ability to provide excellent bone detail.