Dorsal-to-palmar branch neuroanastomosis in horses undergoing palmar digital neurectomy does not reduce neuroma formation or improve outcome.

OBJECTIVE: Chronic foot pain, a common cause of forelimb lameness, can be treated by palmar digital neurectomy (PDN). Complications include neuroma formation and lameness recurrence. In humans, neuroanastomoses are performed to prevent neuroma formation. The aim of the study was to evaluate the outcome of horses undergoing dorsal-to-palmar branch neuroanastomosis following PDN. STUDY DESIGN: Retrospective case series. ANIMALS: Eighty-five horses with PDN and dorsal-to-palmar branch neuroanastomosis. METHODS: Medical records for horses undergoing this procedure at two hospitals between 2015 and 2020 were reviewed. Palmar and dorsal nerve branches of the PDN were transected and end-to-end neuroanastomosis was performed by apposition of the perineurium. Follow-up was obtained from medical records and telephone interviews. Success was defined as resolution of lameness for at least one year. RESULTS: Lameness resolved following surgery in 81/85 (95%) horses with 57/84 (68%) sound at one year. Postoperative complications occurred in 19/85 (22%) cases. The main limitations of the study were an incomplete data set, inaccurate owner recall, and variations in procedure. CONCLUSION: Compared to previous studies, this technique resulted in similar numbers of horses sound immediately after surgery, a comparable rate of postoperative neuroma formation but a higher recurrence of lameness rate at 1 year postoperatively. CLINICAL SIGNIFICANCE: End-to-end neuroanastomosis of the dorsal and palmar branches of the PDN does not reduce the rate of neuroma formation in horses. Long-term outcome was less favorable compared to previously reported PDN techniques.

Computed tomographic assessment of fracture characteristics and subchondral bone injury in Thoroughbred racehorses with lateral condylar fractures and their relationship to outcome.

OBJECTIVE: To investigate the effects of fracture characteristics and concurrent subchondral bone pathology identified with computed tomography (CT) on the racing performance of Thoroughbred racehorses with fractures of the MC3/MT3 lateral condyle. STUDY DESIGN: Retrospective cohort study. SAMPLE POPULATION: Thoroughbred racehorses (n = 50) with a fracture of the MC3/MT3 lateral condyle, which had preoperative CT and internal fixation performed. METHODS: Medical records were reviewed for age, sex, limb, and surgical treatment. Computed tomography scans were evaluated to determine fracture characteristics including length, whether the fracture was incomplete or complete, and displacement. The presence of subchondral bone injury (SBI), sesamoid bone fracture, articular comminution, and fragmentation in the joint was noted. Racing data was obtained from an online database. Univariable and multivariable analyses determined associations between independent variables and outcomes. RESULTS: Thirty-three (66%) horses raced after surgery. Horses with sesamoid bone fractures (P = .021), MC3/MT3 comminution (P = .016) and intra-articular fragmentation (P = .015) were less likely to race postoperatively. Concurrent SBI did not affect outcome. In the final multivariable model, sex (P = .015) and whether a fracture was incomplete or complete (P = .007) were the most significant predictors of racing postoperatively with females and horses with complete fractures being less likely to race. CONCLUSION: The prognosis for racing after a lateral condylar fracture is favorable but is decreased in horses with complete fractures and certain concurrent joint pathology. CLINICAL SIGNIFICANCE: Horses presenting with lateral condylar fractures commonly have concurrent joint pathology. Computed tomography can aid in preoperative evaluation and prognostication by enabling more complete fracture assessment.

The clinical and histopathologic effects of potentiated chlorhexidine in the upper respiratory tract of horses.

OBJECTIVE: To describe the bactericidal and fungicidal properties of a 0.0005% chlorhexidine (CHD) solution potentiated with EDTA-Tris buffers (CHD-EDTA-Tris) and evaluate the safety of 0.0005% CHD-EDTA-Tris in the upper respiratory tract (URT) of normal horses. STUDY DESIGN: Clinical, prospective study. ANIMALS: Eight healthy, skeletally mature horses. METHODS: In vitro-serial dilutions of CHD-EDTA-Tris and EDTA-Tris alone were evaluated for bactericidal and fungicidal activity against Aspergillus fumigatus, Escherichia coli, Staphylococcus aureus, Streptococcus equi subspecies ssp. equi, Streptococcus equi ssp. zooepidemicus, and Pseudomonas aeruginosa. In vivo-eight healthy horses were topically treated twice with 30 ml of 0.0005% CHD-EDTA-Tris. Mucosal samples from each location were evaluated for the presence of inflammation or pathologic lesions. RESULTS: Solutions containing CHD were superior in fungal and bacterial killing to those without. In vitro-a 0.005% CHD-EDTA-Tris was 100% effective against all bacterial and fungal species evaluated, while a 0.0005% CHD-EDTA-Tris was less efficacious against A. fumigatus and S. equi ssp. equi. In vivo-a 0.0005% CHD-EDTA-Tris did not cause any clinical, gross, or histologic abnormalities when topically applied to the equine URT. CONCLUSIONS: A 0.0005% CHD-EDTA-Tris was highly effective for killing of common bacterial and fungal isolates in the equine upper respiratory tract. Short-term topical treatment of the equine URT with dilute CHD did not cause gross or histological inflammation in the tissue. CLINICAL SIGNIFICANCE: A 0.0005% CHD solution with EDTA-Tris should be considered for treatment of clinically relevant inflammatory or infectious conditions or in the URT of the horse.

A retrospective multicenter study on the use of locking compression plates for scapulohumeral arthrodesis in small equids.

OBJECTIVE: To report on technical aspects and outcomes after scapulohumeral arthrodesis (SHA) with a locking compression plate (LCP) in small equids. STUDY DESIGN: Retrospective multicenter case series. ANIMALS: Client-owned Shetland Ponies, Miniature Shetlands, and American Miniature Horses (n = 15). METHODS: Inclusion criteria were completed SHA with an LCP to treat scapulohumeral osteoarthritis/subluxation and availability of postoperative radiographs. Contributing surgeons completed a questionnaire to collect data. All radiographs were reviewed for this study. Follow-up information was obtained via re-admission to the hospital or telephone interview of the referring veterinarian or owner. Outcome was subjectively scored as excellent, good, moderate, or poor based on lameness and function. RESULTS: Sixteen SHAs were performed in 15 equids (body weight 65-145 kg) by nine different surgeons. A narrow 4.5/5.0 mm LCP (7-16 holes) was used in 14 of the 16 SHAs. Follow-up was collected 2.5 years after surgery (median; range: 9 weeks to 10 years). Major complications related to the SHAs were noted in 4 of the 13 horses alive long term, consisting of implant failure (n = 1), surgical site infection (n = 2), and scapular fracture (n = 1). The outcome was graded as excellent in 4, good in 5, and moderate in 4 horses. Two ponies were euthanized because scapulohumeral osteoarthritis and subluxation developed in the contralateral limb. CONCLUSION: Although major complications occurred in about one-third of ponies, SHA with LCP led to long-term survival with good function in most ponies. CLINICAL SIGNIFICANCE: SHA with an LCP offers a high chance for good long-term outcome in small equids although contralateral disease may affect outcome.

Racing performance after surgical repair of medial condylar fracture of the third metacarpal/metatarsal bone in thoroughbred racehorses.

OBJECTIVE: To report the performance of thoroughbred racehorses after surgical repair of a medial condylar fracture of the third metacarpal/metatarsal bone. STUDY DESIGN: Retrospective cohort study. SAMPLE POPULATION: Forty-three horses surgically treated for medial condylar fractures, 30 with previous racing experience, 13 without previous racing experience (nonexperienced). METHODS: Medical records (2009-2017) were reviewed for signalment, radiographic fracture characteristics, repair technique, and postoperative morbidity and mortality. Each experienced horse was matched with two horses randomly selected from its most recent race to serve as healthy controls. Racing performance parameters (race rating, competitive level, speed rating, performance index) and career racing statistics were compared with multiple regression models between injured experienced horses and controls. The career racing statistics for nonexperienced horses were evaluated. Reasons for nonreturn to racing were obtained. RESULTS: The median duration of follow-up was 6 years (minimum 2, maximum 10). Twenty-one of 43 (49%) horses raced again as well as 18 of 30 (60%) experienced horses and three of 13 (23%) nonexperienced horses. Experienced horses were five times more likely than nonexperienced horses to return to racing (95% confidence interval = 0.07-0.58, P = .003). Higher preoperative racing performance parameters were associated with return to racing. Racing performance parameters were lower after the date of fracture in injured horses compared with controls. CONCLUSION: Experienced horses were more likely to return to racing after medial condylar fracture repair, although their performance was generally lower than that of comparably uninjured horses. CLINICAL SIGNIFICANCE: Owners should be aware that horses with medial condylar fractures likely will race at a lower level than their uninjured peers.

Surgical site infection associated with equine orthopedic internal fixation: 155 cases (2008-2016).

OBJECTIVE: To determine the prevalence of surgical site infection (SSI) after internal fixation and to identify risk factors for SSI and nonsurvival. STUDY DESIGN: Retrospective study. ANIMALS: One hundred fifty-five horses with long bone fractures or arthrodesis treated by internal fixation at 1 hospital between 2008-2016. METHODS: Signalment, diagnosis, surgical repair, surgeon, surgical time, antimicrobial use, SSI onset, bacterial identification, and adjunct treatments were recorded. Perioperative variables were analyzed to identify risk factors associated with outcomes. RESULTS: Surgical-site infection was reported in 22 of 155 (14.2%) horses, which is lower than what has been previously reported (P = .003). Horses with fetlock arthrodesis or ulnar fracture were more likely to develop SSI. Local prophylactic antimicrobial therapy was associated with an increased risk of SSI. Horses with SSI were 12 times (P < .0001) less likely to survive to discharge than horses without SSI. Horses with a fetlock or carpal arthrodesis or those with radial/humeral/femoral fractures were less likely to survive. No association was identified between open fractures, open reduction and internal fixation, or surgical times and SSI. CONCLUSION: The prevalence of SSI in this population was lower than what has been previously reported. Horses with fetlock or carpal arthrodesis or radial/humeral/femoral fractures were at increased risk for SSI and/or nonsurvival to discharge. A protective role of local antimicrobial therapy for SSI could not be established. CLINICAL RELEVANCE: The impact of SSI on outcomes of cases of equine internal fixation remains substantial. Identification of cases at higher risk of SSI should influence surgical technique, postoperative management, and early intervention when SSI is suspected. Additional investigation is warranted regarding local antimicrobial therapy.

Arthrodesis of the metacarpophalangeal and metatarsophalangeal joints to treat osteoarthritis in 17 horses.

OBJECTIVE: To describe arthrodesis of the metacarpophalangeal (MCP) or metatarsophalangeal (MTP) joint with a locking compression plate (LCP) and a metallic tension band and report the outcome of horses treated for osteoarthritis (OA) with this technique. STUDY DESIGN: Retrospective case series. ANIMALS: Seventeen horses with OA of the MCP or MTP joint treated with arthrodesis. METHODS: Medical records (2004-2017) of horses treated for OA with arthrodesis of the MCP or MTP joint with an LCP and metallic tension band were reviewed. Preoperative variables included age, sex, breed, affected limb, and lameness grade. Surgical variables included implants used, surgery time, postoperative angle of joint, intraoperative complications, and anesthetic recovery method. Outcome was obtained from medical records and phone interviews. RESULTS: Lameness was scored as 4 out of 5 (range, 2-4) in 13 of 17 horses. All horses survived to discharge and were alive >6 months postoperatively, without any report of long-term complications. All horses were allowed unrestricted turnout, and 1 horse was lightly ridden. No postoperative infections or implant failures were reported. The only complications consisted of cast sores (n = 4). CONCLUSION: Arthrodesis of the MCP/MTP joint was associated with acceptable morbidity and good long-term outcomes in these 17 horses with OA refractory to medical management. CLINICAL SIGNIFICANCE: The morbidity and prognosis after fetlock arthrodesis for OA seem more favorable than reported in horses treated with traumatic disruption of the suspensory apparatus.

Return to racing after surgical management of third carpal bone slab fractures in thoroughbred and standardbred racehorses.

OBJECTIVE: To determine the prognosis for racing of horses surgically treated for slab fractures of the third carpal bone (C3). STUDY DESIGN: Retrospective case study. ANIMALS: Horses (n = 125) surgically treated for C3 slab fractures. METHODS: Medical records of horses surgically treated for dorsal or sagittal C3 fractures were reviewed for age, sex, breed, limb, fracture type, degree of cartilage damage, and surgical treatment. Radiographs were evaluated to determine fracture depth, width, and displacement. Osteophytes, C3 lysis, and fragmentation were scored. Racing performance was obtained from online databases. Univariable and multivariable analyses were used to determine associations between independent variables and outcomes. RESULTS: Fifty-four (43%) horses raced postoperatively. Among thoroughbreds, 35% (30/86) with dorsal fractures and 63% (17/27) with sagittal fractures raced postoperatively. Among standardbreds, 77% (10/13) with dorsal fractures and 0% (0/2) with sagittal fractures raced postoperatively. Fracture displacement, C3 lysis, and cartilage damage affected the likelihood of racing postoperatively. Placement of 3.5-mm screws vs 4.5-mm screws and the placement of fewer screws were associated with improved likelihood of racing. CONCLUSION: The prognosis for postoperative racing of thoroughbreds with dorsal C3 fractures was less favorable than that previously reported. Concurrent joint pathology, such as cartilage damage at time of surgery, affected the ability of the horse to race postoperatively. CLINICAL SIGNIFICANCE: Although internal fixation of C3 slab fractures is required to restore joint congruity, return to racing should be expected in only 42% of thoroughbreds and 67% of standardbreds.

Pancarpal and partial carpal arthrodesis with 3 locking compression plates in 6 horses.

OBJECTIVE: To report the outcome of horses after pancarpal or partial carpal arthrodesis with 3 locking compression plates (LCP). STUDY DESIGN: Case series. ANIMALS: Six horses ranging in age from 8 months to 16 years and weighing 227-580 kg with severe carpal pathology including acute fractures, chronic osteoarthritis, and chronic angular limb deformity. METHODS: Pancarpal or partial carpal arthrodesis was performed with 3 LCP. Autologous cancellous bone grafts were used in 5 of 6 cases to facilitate joint arthrodesis. RESULTS: External coaptation was maintained for 4 to 6 weeks after surgery. Radiographic follow-up was available in all 6 cases, all of which reached arthrodesis and pasture soundness by 4-5 months postoperatively. One case required implant removal at 6 months because of implant exposure through the skin but returned to pasture soundness after removal. CONCLUSION: Carpal instability due to acute fractures or chronic disease was successfully stabilized with 3 short LCP, leading to pasture soundness in all 6 horses. CLINICAL SIGNIFICANCE: The use of 3 short LCP should be considered as a strategy to facilitate pancarpal or partial carpal arthrodesis by providing superior stability without placement of implants in the diaphysis of the radius and third metacarpus.

Wnt10b and Dkk-1 gene therapy differentially influenced trabecular bone architecture, soft tissue integrity, and osteophytosis in a skeletally mature rat model of osteoarthritis.

AIMS: Our goals in the current experiments were to determine if (a) upregulation of Wnt signaling would induce osteoarthritis changes in stable stifle joints and (b) if downregulation of Wnt signaling in destabilized joints would influence the progression of OA. METHODS: At 37 weeks of age, rats were injected in the stifle joint with a recombinant adeno-associated viral vector containing the Wnt-inhibitor Dkk-1 or a Wnt10b transgene. At 40 weeks of age, rats underwent surgical destabilization of the joint. At 50 weeks of age, stifle joints were submitted for micro-computed tomography and histopathological analysis. RESULTS: Injection of either Wnt10b or Dkk-1 transgenes in stable joints improved bone architectural parameters, but worsened soft tissue integrity. Osteophytosis was decreased by Dkk-1, but unchanged by Wnt10b. Destabilization negatively influenced bone architecture, increased osteophytosis, and decreased soft tissue integrity. Dkk-1 exacerbated the negative effects of destabilization, whereas Wnt10b had little effect on these parameters. Osteophytosis was improved, whereas soft tissue integrity was worsened by both transgenes in destabilized joints. CONCLUSIONS: The Wnt-inhibitor Dkk-1 does not appear to completely inhibit the effects of Wnt signaling on bone remodeling. In vivo upregulation of Wnt10b and its inhibitor, Dkk-1, can produce both parallel or contrasting phenotypic responses depending on the specific parameter measured and the fidelity of the examined joint. These observations elucidate different roles for Wnt signaling in stable versus destabilized joints and may help to explain the conflicting results previously reported for the role of Dkk-1 in joint disease.

Use of locking compression plates in ulnar fractures of 18 horses.

OBJECTIVES: To describe the outcome, clinical findings, and complications associated with the use of the locking compression plate (LCP) for various types of ulnar fractures in horses. STUDY DESIGN: Retrospective case series. SAMPLE POPULATION: Client owned horses (n = 18). METHODS: Medical records, radiographs, and follow-up for horses having an ulnar fracture repaired using at least 1 LCP were reviewed. Fifteen of 18 horses had fractures of the ulna only, and 3 horses had fractures of the ulna and proximal radius. RESULTS: All 18 horses were discharged from the hospital. Complications occurred in 5 horses; incisional infection (n = 4, 22%), implant-associated infection (n = 2, 11%), and colic (n = 1, 6%). Follow-up was available for all horses at a range of 13-120 months and 15 horses (83%) were sound for their intended purpose and 3 horses (17%) were euthanatized. One horse was euthanatized for complications associated with original injury and surgery. CONCLUSIONS: The LCP is a viable method of internal fixation for various types of ulnar fractures, with most horses in this series returning to soundness.

Clinical use of computed tomography and surface markers to assist internal fixation within the equine hoof.

OBJECTIVE: To describe clinical use of computed tomography (CT) and hoof surface markers to facilitate internal fixation within the confines of the hoof wall. STUDY DESIGN: Retrospective case series. ANIMALS: Horses (n = 16) that had CT-guided internal fixation of the distal phalanx (DP) or distal sesamoid bone (DSB). METHODS: Drill bit entry point and direction were planned from CT image series performed on hooves with grids of barium paste dots at proposed entry and projected exit sites. Post-implantation CT images were obtained to check screw position and length as well as fracture reduction. Imaging, reduction, and surgical and general anesthesia times were evaluated. Outcome was recorded. RESULTS: Screw position and length were considered near optimal in all horses, with no consequential malposition of bits or screws. Fracture reduction was evident in all cases. Preoperative planning times (at least 2 CT image acquisitions and grid creation) ranged from 10 to 20 minutes. Surgery time ranged from 45 to 90 minutes (mean, 61 minutes) and general anesthesia time ranged from 115 to 220 minutes (mean, 171 minutes). CONCLUSIONS: The combination of CT and surface marker grids allowed accurate positioning of screws in clinical DP and DSB fractures. The technique was simple and rapid. An aiming device is useful for the technique.

Diagnostic and therapeutic arthroscopy in the standing horse.

This article describes diagnostic arthroscopy and arthroscopic management of selected lesions in the standing equine patient. Details on case selection, patient and operating room preparation, and surgical technique are presented. This information will add techniques that avoid general anesthesia to the equine surgeon's armamentarium.

Prospective, longitudinal assessment of subchondral bone morphology and pathology using standing, cone-beam computed tomography in fetlock joints of 2-year-old Thoroughbred racehorses in their first year of training.

BACKGROUND: Catastrophic injuries of the fetlock joints occur in Thoroughbred racehorses and are preceded by stress-induced bone injury. Early detection of subchondral bone injury is essential to prevent irreversible damage or bone failure. OBJECTIVES: To investigate the use of standing, robotic cone-beam computed tomography (CBCT) for assessing longitudinal changes in subchondral bone morphology and pathology of the fetlock joints associated with race training in young Thoroughbreds. STUDY DESIGN: Observational cohort study. METHODS: Forty-one 2-year-old Thoroughbred racehorses were recruited prior to the start of race training. Standing CBCT and radiographs of all 4 metacarpo-/metatarsophalangeal (MCP/MTP) joints were obtained at 0, 6 and 12 months. Hyperdensity, as an estimate of subchondral bone sclerosis, was measured in the distal third metacarpal (MC3)/metatarsal (MT3) bone and proximal phalanx (P1) at each time point on computed tomography. CBCTs were examined for subchondral bone pathology consisting of areas of hypodensity within regions of hyperdensity. RESULTS: Subchondral bone sclerosis increased significantly over time in the medial and lateral MC3/MT3 condyles and in the medial and lateral parasagittal grooves of MC3/MT3. The presence of subchondral bone pathology increased significantly over time in the medial and lateral palmar condyles of MC3/MT3, the lateral parasagittal groove, the medial dorsal condyle and the medial and lateral ridges of P1. MAIN LIMITATIONS: There was attrition of horses due to relocation, change in ownership, and retirement from racing. Husbandry, training regimens and racing schedules were not controlled for in the study. CONCLUSIONS: Standing CBCT is an efficient and effective screening tool for assessing subchondral bone morphology and identifying pathology of the fetlock joint in young Thoroughbred racehorses. CBCT may facilitate early detection of bone pathology allowing for timely intervention and prevention of more serious injuries.

In vitro biomechanical comparison of a 4.5 mm narrow locking compression plate construct versus a 4.5 mm limited contact dynamic compression plate construct for arthrodesis of the equine proximal interphalangeal joint.

OBJECTIVES: To compare the in vitro biomechanical properties of a 4.5 mm narrow locking compression plate (PIP-LCP) with 2 abaxially located transarticular screws and a 4.5 mm limited contact dynamic compression plate (LC-DCP) with 2 abaxially located transarticular screws using equine pasterns. STUDY DESIGN: Experimental. Paired in vitro biomechanical testing of 2 methods for stabilizing adult equine forelimb PIP joints. ANIMAL: Adult equine forelimbs (n = 8 pairs). METHODS: Each pair of PIP joints were randomly instrumented with either a PIP-LCP or LC-DCP plate axially and 2 parasagitally positioned 5.5 mm transarticular screws. The proximal aspect of the proximal phalanx (P1) and the distal aspect of the middle phalanx (P2) were embedded to allow for mounting on a mechanical testing machine. Each construct was tested in both cyclic and subsequently single cycle to failure in 4-point bending. The displacement required to maintain a target load of 1 kN over 3600 cycles at 1 Hz was recorded. Maximum bending moment at failure and construct stiffness was calculated from the single cycle to failure testing. RESULTS: In cyclic testing, significantly more displacement occurred in the LC-DCP (0.46 ± 0.10 mm) than for the PIP-LCP (0.17 ± 0.11 mm) constructs (P = .016). During single cycle testing there was no significant difference in the bending moment between the LC-DCP (148.7 ± 19.4 N m) and the PIP-LCP (164.6 ± 17.6 N m) constructs (P = .553) and the stiffness of the LC-DCP (183.9 ± 26.9 N mm) was significantly lower than for the PIP-LCP (279.8 ± 15.9 N/mm) constructs (P = .011). All constructs failed by fracture of the bone associated with the transarticular screws and subsequently bending of the plates at the middle hole. CONCLUSIONS: Use of the PIP-LCP resulted in a stiffer construct of the same strength as the LC-DCP in vitro using this 4-point bending model.

Identification of a previously unreported site of subchondral bone injury in the dorsodistolateral calcaneus in Thoroughbred racehorses.

BACKGROUND: Increasing accessibility and advancements in computed tomographic (CT) imaging improve understanding of the contributors to poor performance in the Thoroughbred racehorse. OBJECTIVES: To characterise an unreported site of tarsal subchondral bone injury (SBI) in Thoroughbred racehorses. STUDY DESIGN: Retrospective, cross-sectional analytical study. METHODS: Tarsal CT scans of 108 horses were reviewed for evidence of SBI in the dorsodistolateral calcaneus (DDLC). Signalment, including age, breed, sex, and discipline of horses, was recorded. The association of DDLC SBI with Thoroughbred racehorse compared to other breeds/disciplines was calculated. Nuclear scintigraphic scans of the hindlimbs of Thoroughbreds between 2007 and 2022 were also reviewed for increased radiopharmaceutical uptake (IRU) suggestive of DDLC SBI. RESULTS: Tarsal CT scans of 108 horses were analysed and lesion location and type were recorded. DDLC SBI was identified in 8/108 (7.3%) horses. All lesions were found in racing Thoroughbreds (Fischer's exact test p = 0.002) and in 20% (8/40) of racing Thoroughbreds that underwent tarsal CT. DDLC SBI was determined to be the primary cause of lameness in 3/8. Third tarsal bone fracture was considered the primary cause of lameness in 3/8 horses. A total of 1663 nuclear scintigraphic scans of 1603 Thoroughbred horses were reviewed. Increased IRU in the DDLC was present in 13 horses (0.9%). MAIN LIMITATIONS: Study limitations include the retrospective nature of the study, incomplete medical records, lack of sensitivity/specificity data for lesion identification on various imaging modalities or comparison to histopathology, and limited substantive follow-up information. CONCLUSIONS: The DDLC is a previously unreported site of SBI in the Thoroughbred racehorse. The lesion can be the primary source of lameness but may also be found in horses with other clinically relevant osseous injuries. This lesion may be underestimated in the Thoroughbred population. Further investigation is required to determine the true prevalence, clinical relevance, and prognosis in Thoroughbred racehorses with this injury.

CONTEXTO: A maior acessibilidade à tomografia computadorizada (TC) está aprimorando o conhecimento de fatores contribuintes à baixa performance de cavalos puro sangue inglês (PSI) de corrida. OBJETIVOS: Caracterizar um local não previamente descrito de lesão óssea subcondral (LOS) no tarso de cavalos PSI de corrida. DELINEAMENTO DO ESTUDO: Estudo analítico transversal retrospectivo. METODOLOGIA: TC do tarso de 108 cavalos foram revisadas para detectar evidência de LOS na região dorso-distal-lateral do calcâneo (DDLC). Informações de idade, raça, sexo e modalidade esportiva dos cavalos foram revisados. A presença de LOS na região DDLC em cavalos PSI de corrida foi comparada com a presença da mesma lesão em outras raças e modalidades esportivas. Cintilografia nuclear dos membros pélvicos de cavalos PSI de corrida entre 2007 e 2020 também foram revisadas para a presença de evidência de aumento de captação radiofarmacêutica (CRF) sugestiva de LOS na região DDLC. RESULTADOS: LOS na região DDLC for identificada em 8/108 (7.3%) dos equinos. Todas as lesões foram encontradas em PSI de corrida (teste exato de Fischer p = 0.002), e em 20% (8/40) dos PSI de corrida que tiveram o exame de TC feito. LOS na região DDLC foi determinada como a causa primária da claudicação em 3/8 dos casos. Fratura do terceiro osso do tarso foi considerada a causa primária de claudicação em 3/8 dos cavalos. 1663 exames de cintilografia de 1603 cavalos PSI de corrida foram revisados. Aumento da CRF na região DDLC estava presente em 13 equinos (0.9%). PRINCIPAIS LIMITAÇÕES: As limitações deste estudo incluem a natureza retrospectiva do mesmo, prontuários médicos incompletos, falta de dados de sensibilidade e especificidade da lesão nos métodos diagnósticos e comparação histológica, e informação de acompanhamento dos casos limitada. CONCLUSÕES: A região DDLC é um local de LOS não previamente descrito em cavalos PSI de corrida. A lesão pode ser a causa primária de claudicação, mas também pode ser encontrada em casos que apresentam outras lesões relevantes. Essa lesão pode ser subestimada em cavalos PSI de corrida. Mais investigações são necessárias para determinar a prevalência real, a relevância clínica e o prognóstico dessas lesões em cavalos PSI de corrida.

Long-bone fractures in llamas and alpacas: 28 cases (1998-2008).

Treatment and outcome of camelids with long-bone fractures are described. Medical records (1998-2008) of camelids (n = 28) with long-bone fractures were reviewed for signalment, time to presentation, fracture type, method of repair, duration of hospitalization, and post-operative complications. Follow-up information was obtained via telephone interviews with owners. Mean age and weight at presentation were 3.4 years and 56.3 kg, respectively. Twenty-six fractures were treated with internal fixation (n = 11), external fixation (n = 10), combination of internal and external fixation (n = 3), amputation (n = 1), and external fixation followed by amputation (n = 1). Long-term follow-up information was obtained for 19 of the 26 animals. The post-operative complication rate was 23% and owner satisfaction was high. Animals with open fractures were more likely to experience complications. Internal fixation was associated with superior alignment and outcome. Internal fixation techniques should be recommended for camelids.

Recombinant fibroblast growth factor-18 (sprifermin) enhances microfracture-induced cartilage healing.

Posttraumatic osteoarthritis is a disabling condition impacting the mostly young and active population. In the present study, we investigated the impact of intra-articular sprifermin, a recombinant truncated fibroblast growth factor 18, on the outcome of microfracture treatment, a widely used surgical technique to enhance cartilage healing at the site of injury. For this study, we created a cartilage defect and performed microfracture treatment in fetlock joints of 18 horses, treated joints with one of three doses of sprifermin (10, 30, or 100 µg) or with saline, hyaluronan, and evaluated animals functional and structural outcomes over 24 weeks. For primary outcome measures, we performed histological evaluations and gene expression analysis of aggrecan, collagen types I and II, and cartilage oligomeric matrix protein in three regions of interest. As secondary outcome measures, we examined animals' lameness, performed arthroscopic, radiographic, and computed tomography (CT) scan imaging and gross morphology assessment. We detected the highest treatment benefit following 100 µg sprifermin treatment. The overall histological assessment showed an improvement in the kissing region, and the expression of constitutive genes showed a concentration-dependent enhancement, especially in the peri-lesion area. We detected a significant improvement in lameness scores, arthroscopic evaluations, radiography, and CT scans following sprifermin treatment when results from three dose-treatment groups were combined. Our results demonstrated, for the first time, an enhancement on microfracture outcomes following sprifermin treatment suggesting a cartilage regenerative role and a potential benefit of sprifermin treatment in early cartilage injuries.

Serum amyloid A and fibrinogen as markers for early detection of surgical site infection associated with internal fixation in the horse.

The objective of this study was to determine the diagnostic ability of serum amyloid A (SAA) and fibrinogen for early detection of surgical site infection (SSI) after equine internal fixation. Horses undergoing internal fixation for fracture, arthrodesis, or osteotomy with internal fixation for limb deformity were included in the study. SAA and fibrinogen were measured on blood samples preoperatively and on days 1, 3, 5, 7, 10, and 14 postoperatively. Statistical analysis included use of Spearman's rank correlation, logistic regression, and calculating the area under the receiver operating characteristic (ROC) curve. SAA and fibrinogen measurements were both associated with SSI, with SAA being considered an excellent marker (area under the ROC curve 0.8) and fibrinogen being considered acceptable (<0.8). As the amount of time postoperatively increased, SAA elevations indicated a higher likelihood of SSI (area under the ROC curve 0.8 compared with fibrinogen 0.7). SAA and fibrinogen were predictive markers of SSI and SAA is of greater diagnostic utility when compared with fibrinogen. Persistent elevations of SAA postoperatively are associated with the development of SSI. Serial monitoring of SAA can be used to help predict the development of SSI in horses undergoing internal fixation. This may lead to earlier suspicion, and therefore recognition and treatment of SSI.

Computed tomography or magnetic resonance imaging-assisted partial hoof wall resection for keratoma removal.

OBJECTIVES: To (1) describe the computed tomography (CT) and magnetic resonance imaging (MRI) appearance of keratomas; (2) describe a CT- or MRI-assisted partial hoof wall resection technique for removal of keratomas; and (3) evaluate the morbidity and postoperative outcome of these horses. STUDY DESIGN: Case series. ANIMALS: Horses (n=10) with keratoma. METHODS: Data retrieved from medical records included signalment, lameness duration and grade, physical and diagnostic evaluation findings, CT and MRI technique and findings, surgical details, histopathologic diagnosis, postoperative treatment, and complications experienced. Long-term outcome was obtained by telephone interviews of owners. RESULTS: Complications including excessive granulation tissue formation and infection were seen in 2 horses (20%). No keratoma recurrence occurred. Follow-up information was available for 8 horses; 7 were sound and had resumed work. Mean time until they became sound was 2.7 months, and mean time until work resumed was 3.6 months. CONCLUSIONS: CT and MRI can be used to accurately identify the location of keratomas. Postoperative complications may be decreased by creating smaller hoof wall defects, filling the defects with antimicrobial-impregnated polymethylmethacrylate, and placing a shoe early in the postoperative period.