Prevalence, radiographic resolution and outcomes of slab fractures of the third and central tarsal bones in juvenile Thoroughbred horses.

BACKGROUND: Veterinarians are required to interpret the significance of radiographic findings for sale, soundness and future racing performance of weanling and yearling Thoroughbreds. We investigated the prevalence and radiographic appearance of slab fractures of the third (T3) and central tarsal (Tc) bones. METHODS: Weanling and yearling horses with complete or incomplete T3 or Tc fracture were identified by searching a database of radiographs. The prevalence and radiographic appearance at initial diagnosis and after continued pasture turnout, as well as prognosis for racing, of fractures of T3 and Tc were determined. RESULTS: Fractures were identified in 186 tarsi (184 T3 fracture only, 1 Tc fracture only, 1 Tc and T3 fracture) of 157 horses (126 unilateral T3, 29 bilateral T3, 1 contralateral Tc and T3, 1 unilateral Tc and T3) from 7676 examinations. The prevalence of T3 and Tc fractures was 2.40 (95% CI 2.07, 2.76) and 0.04 (95% CI 0.01, 0.11) per 100 radiographic examinations respectively. Fractures were identified on the D556-65°MPlLO view and occurred by survey examination at 11.1 ± 1.3 months in 85.7% horses. At initial diagnosis, 84.3% of T3 fractures appeared incomplete and involved the distal articular surface. Fracture score improved (P < 0.001), and dorsal modelling (P < 0.001) and osteoarthritis score increased in the distal intertarsal joint (P < 0.001), but not the tarsometatarsal joint, between survey and repository examinations. Fractures healed by repository examination in 71.9% of tarsi if there was > 6 months between examinations. There was no difference in sale price, and horses with T3 fractures had fewer trials when 2 and 3 years old (P = 0.023), yet no difference in other parameters of racing success when 2 or 3 years old compared with controls. CONCLUSION: Tarsal slab fractures can occur in juvenile Thoroughbreds and most heal with continued pasture turnout of > 6 months. Further investigation is required to determine risk factors and before making firm conclusions regarding the optimal management, prognosis for racing and long-term soundness.

Fragmentation of the dorsal distal aspect of the talus on weanling survey and pre-sale radiographs of juvenile Thoroughbreds: prevalence and 2- and 3-year-olds racing performance.

BACKGROUND: Fragmentation of the dorsal aspect of the distal talus (FDDT), at the dorsolateral articular margin of the proximal intertarsal joint (PITJ) on pre-sale radiographs of yearling Thoroughbreds has not been previously described and data to support decisions made by veterinarians to predict future racing potential of horses with these lesions are lacking. METHODS: In this retrospective case-control study we aimed to determine the prevalence of FDDT in juvenile Thoroughbreds and to report their race records. From a database of survey and repository radiographic examinations of 5709 horses, 36 with FDDT were identified. RESULTS: The prevalence of FDDT was 0.63% (36/5709; 95%CI 0.44, 0.87), compared with 5.01% (286/5709; 95%CI 4.46, 5.61) for osteochondrosis of the distal intermediate ridge of the tibia in the same population. In most cases, a single oval-shaped fragment 1-12 mm in diameter was present. When comparing cases with matched controls, there were no significant differences in mean sale price, whether horses started in a trial or race and mean number of starts, wins, places and prize money when 2- and 3-years old. CONCLUSION: FDDT did not appear to affect racing performance, although a larger-scale study is warranted to confirm this finding.

Dystocia in a referral hospital setting: approach and results.

REASONS FOR PERFORMING STUDY: Dystocia in the mare is an emergency in which duration has a profound effect on survival of the foal. Specific examination of the effects of dystocia duration on foal survival provides information to enable horse care personnel and veterinarians to manage these cases more effectively and maximise the chances of obtaining a live foal. HYPOTHESIS: Dystocia duration would have a negative impact on foal survival while method of dystocia resolution would not have an effect on foal survival. Additionally, we were interested in determining the effects of dystocia on subsequent fertility. METHODS AND RESULTS: In the years 1986-1999, 247 dystocias were admitted. Of these, 91 % resulted in survival and discharge of the mare, 42% in delivery of a live foal, and 29% of foals survived to discharge. Period from hospital arrival to delivery for foals alive at discharge (23.0 +/- 14.1 mins) was not significantly different than for foals not surviving (24.8 +/- 10.6 mins) (P > 0.05); and from chorioallantoic rupture to delivery for foals alive at discharge (71.7 +/- 343 mins) was significantly less than for foals not surviving (853 +/- 37.4 mins) (P < 0.05). Average predystocia live foaling rates for all mares with available records was 84%. Overall post dystocia live foaling rates over the entire period of this study were 67%. Of mares bred in the year of the dystocia, 59% had a live foal in the year following. CONCLUSIONS: Based on these results, dystocia duration has a significant effect on foal survival and resolution methods should be chosen to minimise this time, as the difference between mean dystocia duration for foals that lived and those that did not in this study was 13.6 mins. Post dystocia foaling rates reported here are higher than previously reported for both same-season and overall breedings, indicating same-season breeding may be rewarding for select dystocia cases. POTENTIAL RELEVANCE: Dystocia resolution methods that minimise delivery time may maximise foal survival. Post dystoicia breeding may be rewarding in select cases.

Qualitative and quantitative documentation of the racing performance of 461 Thoroughbred racehorses after arthroscopic removal of dorsoproximal first phalanx osteochondral fractures (1986-1995).

The purpose of this study was to examine the longevity of postoperative careers and quality of performance of 461 Thoroughbred racehorses after arthroscopic removal of dorsoproximal first phalanx (P1) osteochondral fractures. Six hundred and 59 dorsoproximal P1 chip fractures were removed arthroscopically from 574 joints in 461 horses presented for lameness or decreased performance attributed to the chip fractures. Radiological and arthroscopic examination revealed an average of 1.43 fragment sites/horse, 1.15 fragment sites/joint and 1.25 affected joints/horse. Eighty-nine percent of the horses (411/461) raced after surgery and 82% (377/461) did so at the same or higher class. Fifty horses did not race after surgery. Sixty-eight percent of the horses raced in a Stake or Allowance race postoperatively. Data, previously undocumented, establishes that the quantity and quality of performance is not diminished after arthroscopic treatment of dorsoproximal P1 fragmentation. Surgical removal of chip fractures is a means of preserving the economic value of an injured Thoroughbred, allowing a rapid and successful return to racing at the previous level of racing performance.

Characterisation of the type and location of fractures of the third metacarpal/metatarsal condyles in 135 horses in central Kentucky (1986-1994).

The objective of this retrospective study was to provide a detailed description of the characteristics of condylar fractures represented in a population of 135 horses who sustained 145 fractures. Records and radiographic studies were examined. Fifty-nine percent of the horses were male and the majority Thoroughbreds. The distribution of fractures was 37% incomplete-nondisplaced, 30% complete-nondisplaced and 32% complete-displaced. The right front was more likely to sustain a complete-displaced fracture, whereas the left front was more likely to sustain an incomplete-nondisplaced fracture. Forelimbs (81%) and lateral condyles (85%) were more likely to be involved. Contrary to previous studies, the right forelimb was slightly more often involved than the left. Fractures tended to involve the middle portion of the condyle (59%). The mean length of all fractures was 75+/-3.8 mm. Axial fractures and medial condyle fractures tended to be longer. Fifteen percent of the fractures had definitive articular comminution. Ninety-five percent of fractures with articular comminution were associated with complete fractures. When fractures entered the middle area of the condyle, 23% had articular comminution. Eight of the fractures spiralled, all involved forelimbs. Concurrent lesions included proximal phalanx chip fractures, sesamoid fractures, sesamoiditis, proximal phalanx fractures, 'splint' bone periostitis and ligamentous injuries. The complete description of the fractures in this group of horses allows us better to define the condylar fracture, compare these fractures to previous studies and establish new data for use in defining prognosis.

Results of treatment of 145 fractures of the third metacarpal/metatarsal condyles in 135 horses (1986-1994).

The objectives of this study were to correlate condylar fracture characteristics and type of treatment with subsequent capacity for athletic ability, and to determine the characteristics of healing that affect prognosis after fracture fixation. Medical records, post operative radiographic studies and race records were examined for 135 horses sustaining 145 fractures. Sixty-five percent of horses overall started in a race post injury (SPI) in a mean time of 9.7 months with a mean of 13.7 races post injury. Having raced pre-injury did not confer an advantage to starting post injury, though nonstarters pre-injury tended to take longer to return. For horses starting pre- and post injury, 66% improved or maintained their race class level after injury, whereas 64.2% decreased their race earnings post injury. Eighty-five percent of the fractures received internal fixation, of which 70% were complete fractures. Eighty-seven percent of horses with incomplete-nondisplaced fractures treated conservatively raced post injury. The percent SPI for incomplete-nondisplaced, complete-nondisplaced and complete-displaced fractures treated with internal fixation were 74%, 58%, and 60%, respectively. Males (72%) raced post injury more frequently than fillies (53%), and may represent a truer probability of SPI. Spiral fractures tended to take longer until their first start (mean 13.3 months). Fifty-two percent of horses with articular fragments were able to race post injury. Horses were more likely to start if 2-4 month radiographic healing revealed no evidence of the fracture except the presence of lag screws. Based on this series of cases, the majority of horses, with proper treatment, were able to return to racing regardless of fracture characteristic. Prognosis appeared to be affected by the severity of the injury to the joint, the presence of articular comminution and the quality of surgical repair.

Colopexy.

Colopexy is a surgical procedure designed to create an adhesion from the ventral colon to the body wall to prevent recurrence of large colon volvulus or displacement, and is a useful technique to prevent recurrence of this disease. Colopexies usually are reserved for broodmares, because this is the population of horses that is most predisposed to recurrence of large colon volvulus.

Colonic luminal pressure in horses with strangulating and nonstrangulating obstruction of the large colon.

Colonic luminal pressure (median, range) measured during ventral midline celiotomy in 69 horses with strangulating obstruction (SO) of the large colon (SO; > or = 270 degrees large colon volvulus; 27 cm H2O: 2 to 80 cm H2O) was greater (P = .0023) than that measured in 37 horses with nonstrangulating obstruction (NSO) of the large colon (NSO; < or = 180 degrees volvulus or a nonstrangulating displacement; 18 cm H2O; 6 to 46 cm H2O). Sixty-five percent (45 of 69) of horses with SO and all horses with NSO survived. Survival analysis was restricted to 59 horses with large-colon SO that survived to hospital discharge or met the criteria specified for classification as nonsurvivors. Colonic luminal pressure in nonsurvivors (48.5 cm H2O; 34 to 80 cm H2O) was higher (P =.0001) than that measured in survivors (18 cm H2O; 2 to 50 cm H2O) of SO. From response operating characteristic curves, a luminal pressure of 38 cm H2O optimized the distribution of horses with SO into survivor and nonsurvivor groups. Sensitivity, specificity, and positive and negative predictive values for a colonic luminal pressure greater than 38 cm H2O in predicting nonsurvival were 0.89, 0.91, 0.72 and 0.97, respectively. Measurement of colonic luminal pressure may be useful for predicting survival in horses with colonic volvulus.

Neoplasia.

Equine tumors are rather uncommon; however, of the body regions, the head is a relatively common location for neoplasia, including sarcoids and squamous cell carcinomas of the skin, tumors of the sinus/nasal cavity, and bony tumors of the head. Tumors discussed in the article include odontogenic and bony tumors; sarcoids; tumors of the guttural pouch and pharyngeal and oral mucosa; tumors of the larynx; and tumors of the paranasal sinuses and nasal passages. In general, tumors involving deeper structures of the head carry a poor prognosis; however, some tumors such as sarcoids, ossifying fibromas, and osteomas of the paranasal sinus often can be treated effectively by cytoreductive surgery, with or without adjunctive treatment modalities. The clinical signs, prognoses, and therapeutic options for specific tumor types and locations are reviewed. Ophthalmic tumors are not discussed.

Lesions of the caudal aspect of the femoral condyles in foals: 20 cases (1980-1990).

Medical records and radiographs were reviewed from 20 foals with caudal femoral condylar lesions. Osseous lesions were classified radiographically into 3 categories. Type-I lesions were characterized by a discrete area of radiolucency within the subchondral bone of the caudal aspect of a femoral condyle and were associated with septic arthritis and osteomyelitis. Type-II lesions had localized, osseous irregularities involving < 50% of the femoral condyle. Type-III lesions had widespread irregularities involving a large area of the condyle, and in 5 foals with type-III lesions, there was a thin osseous fragment displaced from the condyle and free in the femorotibial joint pouch. Foals with type-I and -III lesions were severely lame and often required assistance to stand. Foals with type-II lesions were not as lame, but lameness was evident at the trot and was exacerbated by flexion of the affected stifle. Cytologic evaluation of the synovial fluid from foals with type-I lesions was compatible with septic arthritis, whereas synovial fluid from foals with type-II and -III lesions was not septic. Surgical exploration and debridement were performed in 4 foals. Two foals with type-II lesions are currently performing athletically. The remaining 2 foals, in which surgery was performed, had type-III lesions; both of those foals were euthanatized at surgery because of the severity of the lesions. Follow-up information was available in 5 foals that did not have surgery. Two foals with type-I lesions and 1 foal with a type-III lesion were sound 1 year after diagnosis. One foal with a type-II lesion had residual lameness that prevented performance, and 1 foal with a type-III lesion was salvaged for breeding. Eleven foals were euthanatized and available for postmortem examination. Gross examination of the joints in foals with type-I lesions revealed a subchondral bone defect with intact articular cartilage in 3 of 4 foals examined. In 1 foal with a type-II lesion, a gross examination was performed, which revealed a focal indentation of the articular cartilage and on cross section had a retained cartilaginous core. Postmortem examination of 4 foals with type-III lesions revealed a large, denuded area with a shell-like cartilage fragment free within the joint. Two additional foals within this same group had marked irregularity of the articular cartilage with deep reticulation in the articular surface. In 2 of 3 foals examined with type-I lesions, histologic examination revealed suppurative osteomyelitis. The third foal in this group had changes compatible with focal ischemia.(ABSTRACT TRUNCATED AT 400 WORDS)

Colopexy in broodmares: 44 cases (1986-1990).

Colopexies were performed in 44 broodmares requiring abdominal surgery for large colon volvulus or right dorsal displacement of the large colon. Colopexies were performed by suturing the lateral bands of the left and right ventral colon to the ventral abdominal wall. Forty-seven percent of the mares in which a colopexy was performed had previous surgery for a large colon volvulus or right dorsal displacement of the large colon. Postoperative complications considered directly associated with the colopexy procedure were intermittent abdominal pain in 7, reoperation in 5, subcutaneous fistulous tracts in 1, and catastrophic rupture of the left ventral colon in 2 horses. Thirty-six horses survived greater than 6 months after colopexy, 34 of which had complete follow-up examinations. Twenty-seven mares have foaled at least once subsequent to the colopexy procedure, totalling 40 foals. Colopexy was considered a viable technique to prevent recurrence of large colon displacement or volvulus in selected predisposed populations.

Retrospective study of 38 cases of femur fractures in horses less than one year of age.

Medical records of 38 horses less than 1 year of age and diagnosed as having a fracture of the femoral diaphysis, metaphysis or distal physis were evaluated. Twenty-six foals had fractures of the femoral diaphysis or metaphysis with the most common fracture configuration being comminuted. Twelve foals had distal physeal fractures with the most common fracture configuration being a Salter-Harris type II. Twenty-one foals with fractures of the capital femoral physis, neck or greater trochanter during the same time period were excluded from this study. Surgical repair was attempted in 16 diaphyseal and 2 distal physeal fractures. Most of the diaphyseal fractures were repaired by placing plates on the lateral and cranial surfaces of the bone. Dynamic condylar screw plates or angle blade plates were used for increased bone purchase in 4 foals with short distal fragments. Five foals with distal physeal fractures were treated; 2 were surgically treated by placing an angle blade plate on the lateral cortex, and 3 foals with minimally displaced distal physeal fractures were managed with stall confinement. Eight of the 16 surgically repaired diaphyseal fractures healed. Fracture location and configuration was not a determinant of outcome, but the mean age of foals with successfully repaired diaphyseal fractures was 2 months compared with 4 months for the unsuccessful cases, indicating that the age and size of the foal was important. Long-term follow up revealed that 6 of the 8 successfully repaired diaphyseal fractures had no residual effects of the fracture observed during performance of the horse for its intended use. Only 1 of the 2 surgically repaired distal physeal fractures healed, but this horse was eventually killed because of unthriftiness related to a malabsorption syndrome. Some form of complication developed in 13 of the 18 surgically repaired fractures. Infection was the primary cause of failure. The greatest determinant associated with infection was the inability to control post-surgical seroma formation.

Cystic structures in the guttural pouch (auditory tube diverticulum) of two horses.

Two horses were examined for compression of the pharynx from the dorsal pharyngeal wall. Neither horse had a patent opening of 1 of the guttural pouches. Radiography of the guttural pouch region revealed a retropharyngeal opacity that occluded 1 guttural pouch. Organisms were not isolated on bacteriologic culture of fluid obtained from the affected guttural pouch. Surgical exploration of the guttural pouch revealed the lining to be easily removeable by blunt dissection in 1 horse; however, the lining was more firmly attached and removal was not attempted in the second horse. A fenestration between the normal and affected guttural pouch was created in both horses to allow for drainage. The etiopathogenesis of the cyst in the guttural pouches is unknown.

Subcutaneous emphysema from an axillary wound that resulted in pneumomediastinum and bilateral pneumothorax in a horse.

A 5-year-old Thoroughbred gelding was examined because of a small axillary wound sustained 5 days earlier and had resulted in extensive subcutaneous emphysema. Three days after admission, the horse's respiratory rate had increased to 72 breaths/min, and the horse appeared anxious and distressed. Thoracic radiography revealed pneumomediastinum and severe bilateral pneumothorax. Tube thoracostomy was performed on both hemithoraxes. The drains were connected to one-way suction valves and suction devices to decompress the thorax. A nasopharyngeal catheter was inserted, and oxygen insufflation was started. Cross ties were placed on the horse to limit movement, and the wound was packed. The horse improved within 30 minutes after initiating treatment. The horse was released 15 days after the development of pneumothorax, at which time the pneumothorax had resolved, the wound was no longer open, and the subcutaneous emphysema had greatly decreased. Although subcutaneous emphysema is usually regarded as a temporary cosmetic disfigurement, it can lead to serious complications such as pneumothorax. This case demonstrates that subcutaneous emphysema can lead to a life-threatening pneumothorax if the pressure is great enough to migrate through the mediastinum and into the pleural cavity. Horses with subcutaneous emphysema should be kept in confinement and monitored for the development of pneumothorax.