A multi-centre cohort study investigating the outcome of synovial contamination or sepsis of the calcaneal bursae in horses treated by endoscopic lavage and debridement.

BACKGROUND: Previous studies investigating factors associated with survival following endoscopic treatment of contamination/sepsis of the calcaneal bursa are limited. OBJECTIVES: To investigate the factors associated with survival in horses with contamination/sepsis of the calcaneal bursae treated endoscopically and to describe the bacterial isolates involved in the synovial infections. STUDY DESIGN: Retrospective analysis of clinical records. METHODS: Medical records from 128 horses with contamination/sepsis of the calcaneal bursae treated by endoscopic lavage at seven equine hospitals were reviewed. A follow-up questionnaire was used to determine survival and return to athletic performance. Descriptive statistics and Cox proportional hazards survival models were used to determine factors associated with survival. RESULTS: Horses underwent one (n = 107), two (n = 19), or three (n = 2) surgeries. Survival to hospital discharge was 84.4%. Univariable survival analysis revealed that administration of systemic antimicrobials prior to referral was associated with reduced mortality (hazard ratio, [HR] 0.41, 95% CI 0.18-0.91, P = 0.03). Increased mortality was associated with bone fracture/osteomyelitis (HR 2.43, 95% CI 1.12-5.26, P = 0.03), tendon involvement (≥30% cross sectional area) (HR 3.78 95% CI 1.78-8.04, P = 0.001), duration of general anaesthesia (HR 1.01, 95% CI 1.00-1.02, P = 0.04), post-operative synoviocentesis (HR 3.18, 95% CI 1.36-7.43, P = 0.006) and post-operative wound dehiscence (HR 2.5, 95% CI 1.08-5.65, P = 0.04). Multivariable Cox proportional hazards model revealed reduced mortality after systemic antimicrobial administration prior to referral (HR 0.25, 95% CI 0.11-0.60, P = 0.002) and increased mortality with tendinous involvement (≥30% cross-sectional area) (HR 7.92, 95% CI 3.31-19.92, P<0.001). At follow-up (median 30 months, range 0.25-13 years, n = 70) 87.1% horses were alive, 7.1% had been euthanised due to the calcaneal injury and 5.7% had been euthanised for unrelated reasons. From 57 horses with athletic performance follow-up, 91.2% returned to the same/higher level of exercise, 5.3% to a lower level and 3.5% were retired due to persistent lameness of the affected limb. MAIN LIMITATIONS: Retrospective study and incomplete follow-up. CONCLUSION: Endoscopic treatment of contamination/sepsis of the calcaneal bursae has an 84% survival rate to hospital discharge. Tendinous involvement reduced survival whilst systemic antimicrobials administration prior to referral improved survival.

Improved diagnostic criteria for digital flexor tendon sheath pathology using contrast tenography.

BACKGROUND: Pathology of the digital flexor tendon sheath is a significant cause of lameness in the horse. Imaging is important to identify lesions and inform on prognosis prior to tenoscopic surgery. OBJECTIVES: To use a large population to evaluate 1) the sensitivity and specificity of digital flexor tendon sheath (DFTS) contrast radiographs in diagnosing manica flexoria (MF) tears, deep digital flexor tendon (DDFT) tears and constriction of the palmar/plantar annular ligament (PAL) using novel criteria; 2) predisposition to pathology in signalment and limb affected. STUDY DESIGN: Multicentre retrospective cohort study. METHODS: The medical records of 206 horses with lameness localised to the DFTS, contrast radiographs and subsequent tenoscopic surgery were reviewed. Breed and limb predispositions were evaluated for pathology of the DDFT, MF and PAL constriction. Contrast radiographs of the DFTS were reviewed by four masked operators and for each pathology the sensitivity, specificity and interobserver variability were calculated. RESULTS: Contrast tenography was a sensitive test for MF tears (92% confidence interval [CI] 88.4-94.4%; specificity 56%, CI 51.1-61.1%) and specific for diagnosing DDFT tears (73%, CI 68.6-76.8%; sensitivity 54%, CI 47.8-60.2%) but had a lower sensitivity (71%, CI 65.1-75.9% ) and specificity (45%, CI 39.1-52.0%) for PAL constriction. It had good to substantial interobserver agreement for MF and DDFT tears (Krippendorff's alpha 0.68 and 0.46 respectively). Ponies (57%) and cobs (58%) were significantly more likely to be affected with MF tears (other breeds 20-39%, P = 0.003) and Thoroughbreds (50%), warmbloods (45%) and draught breeds (48%) were more likely to have DDFT tears (other breeds 22-34%, P = 0.01). MF tears and PAL constriction were overrepresented in the hindlimbs compared to DDFT tears in forelimbs. MAIN LIMITATIONS: No standardisation of contrast radiographs was possible. The subjectivity of diagnosis of PAL constriction may also have led to bias. Radiographs were read as JPEGS reducing ability to manipulate images. CONCLUSIONS: Contrast radiography of the DFTS is accurate in the pre-operative diagnosis of DFTS pathologies. Different pathologies are overrepresented in certain breeds and limbs.

Metabolomic analysis of synovial fluid from Thoroughbred racehorses diagnosed with palmar osteochondral disease using magnetic resonance imaging.

BACKGROUND: Palmar osteochondral disease (POD) is a common cause of lameness in competition horses. Magnetic resonance imaging (MRI) is the most sensitive diagnostic modality currently available, however it may not be financially or logistically practical for routine screening of POD. There is increasing interest in the use of metabolomics for diagnosis prior to progression to irreversible damage. OBJECTIVES: To determine metabolite levels in synovial fluid (SF) of horses with a clinical diagnosis of POD based on diagnostic analgesia and MRI, with the hypothesis that metabolomic profiles differ between diseased and healthy joints. STUDY DESIGN: Prospective clinical study. METHODS: Synovial fluid was collected from metacarpo/tarsophalangeal joints (MC/TPJ) of 29 horses (n = 51 joints), including 14 controls (n = 26) and 15 cases (n = 25), the latter with lameness localised to the MC/TPJ and MR changes consistent with POD (n = 23). Spectra were produced using 1 H-nuclear magnetic resonance (NMR) spectroscopy and analysed. RESULTS: Twenty-five metabolites were recognised associated with various biosynthetic and degradation pathways. The metabolite abundances within the controls demonstrated increased variability compared with the clinical group. The low level of variance between the spectra of the two groups was explained by five principal components. Cross-validation of the cohort demonstrated modest separation of predictive power (R2  = 0.67; Q2  = 0.34). Although statistical significance was not achieved, the most influential metabolites were glucose and lactate. MAIN LIMITATIONS: The modest sample size and variation in signalment, background and presenting condition of the controls may have impacted the discriminative power of the constructed models. The lack of matched controls, differences in time of fluid collection and freezing times may have also reduced accuracy when representing metabolite profiles. CONCLUSIONS: This study identified and quantified metabolites present in MC/TPJ SF of clinical cases with POD.

Fracture of the medial intercondylar eminence of the tibia in horses treated by arthroscopic fragment removal (21 horses).

BACKGROUND: Fractures of the medial intercondylar eminence of the tibia (MICET) are scarcely reported in horses. OBJECTIVES: To report the clinical and diagnostic findings, surgical treatment and outcome in a series of horses presented with MICET fracture and treated with arthroscopic fragment removal. STUDY DESIGN: Multicentre retrospective case series. METHODS: Case records of horses diagnosed with MICET fractures that had undergone surgical treatment were reviewed. Follow-up information was obtained from re-examination visits and/or owners. RESULTS: Twenty-one cases were identified at 9 equine hospitals between 2004 and 2016. A history of trauma and acute onset of lameness was reported in 12 horses. All cases underwent fracture removal via arthroscopy of the medial femorotibial joint. The cranial cruciate ligament was intact in 6 horses and damaged in 15 horses (damage was ≤25% [n = 9], 25-50% [n = 4] or ≥50% [n = 2] of the cross-sectional area). The cranial ligament of the medial meniscus was damaged in 11 horses (≤25% [n = 8], 25-50% [n = 3]). The medial meniscus was damaged in 5 horses and articular cartilage damage was identified in 14 horses (mild [n = 8], moderate [n = 6]). Follow-up information (median 14 months; 4 months-6 years) was available for 20 cases; 2 horses were sound but convalescing; 13 horses were sound and returned to their previous or expected use. Of the 4 horses with the most severe changes to the articular soft tissue structures, 2 remained lame and 2 were subjected to euthanasia because of persistent lameness. MAIN LIMITATIONS: The retrospective, multicentre nature of this study and the limited number of horses are the main limitations. CONCLUSIONS: Fractures of the MICET are commonly associated with a traumatic event. Prompt diagnosis and early arthroscopic removal of the fracture are recommended.

Post operative synovial sepsis following endoscopic surgery: Increased risk associated with the carpal sheath.

REASONS FOR PERFORMING STUDY: The overall rate of sepsis following endoscopic surgery of synovial structures has not previously been documented. Clinical observation has led to the conjecture that tendon sheaths, in particular the carpal flexor tendon sheath, are more prone to post operative synovial sepsis than other synovial structures. OBJECTIVES: To document and investigate the rate of post operative synovial sepsis following elective endoscopic surgery. STUDY DESIGN: Retrospective case series. METHODS: The medical records of horses that underwent arthroscopy, tenoscopy or bursoscopy at Donnington Grove Veterinary Surgery between January 1999 and July 2012 were reviewed. The signalment, anatomical structure involved, use of electrosurgery, tourniquet or motorised resector, presence of a fracture, whether surgery was performed with the horse standing or under general anaesthesia and the number of structures examined were recorded. Multivariable logistic regression was used to test the association between the selected variables and synovial sepsis. Odds ratios (OR) and 95% confidence intervals (CI) were calculated. Level of significance was P<0.05. RESULTS: There were 1670 horses that underwent endoscopic surgery of 3159 synovial structures: 2517 joints, 583 tendon sheaths and 59 bursae. There were 16 cases of post operative sepsis in 16 horses; therefore, the infection rate was one per 100 horses or 5 per 1000 procedures. Carpal sheath tenoscopy was associated with an OR of developing post operative synovial sepsis of 14.9 (95% CI 4.8-45.9, P<0.001) compared to other synovial structures. Tendon sheath endoscopy had an OR of developing post operative synovial sepsis of 5.21 (95% CI 1.24-21.91, P<0.02) compared to other synovial structures. CONCLUSION: Surgeons should be aware that tendon sheaths and the carpal sheath in particular appear to have higher odds of developing sepsis following endoscopic surgery.

Outcome of horses with synovial structure involvement following solar foot penetrations in four UK veterinary hospitals: 95 cases.

REASONS FOR PERFORMING STUDY: The factors associated with outcome following solar foot penetration involving synovial structures treated using endoscopic lavage have not been described in the UK population. OBJECTIVES: To provide descriptive data on horses with synovial contamination or sepsis following solar penetration in 4 UK equine referral hospitals and to identify specific factors associated with the outcome. STUDY DESIGN: Retrospective case series. METHODS: Data were collected from 4 veterinary hospitals. Follow-up data were obtained via a telephone questionnaire. Two multivariable logistic regression models were generated. Model 1 included all horses with synovial contamination following foot penetration undergoing surgical treatment, with the outcome variable being euthanasia during hospitalisation. Model 2 included all horses surviving anaesthesia, with the outcome variable being failure to return to pre-injury athletic function. RESULTS: Ninety-five horses were included. Overall, 56% of horses survived to discharge and 36% of horses returned to pre-injury athletic function. Model 1 included penetration of the central frog sulcus (odds ratio [OR] 10, 95% confidence interval [CI] 1.9-51.8), concurrent distal phalanx involvement (OR 32, 95% CI 2.6-101.9), increasing days to presentation (OR 1.2, 95% CI 1.0-1.3) and hospital. Model 2 included increasing days to presentation (OR 1.1, 95% CI 1.1-1.6), breed (OR 32, 95% CI 2.2-135.4), more than one surgery (OR 5.6, 95% CI 1.0-32.7) and hospital. CONCLUSIONS AND POTENTIAL RELEVANCE: Synovial involvement following solar foot penetration has a guarded prognosis for survival to discharge and a poor prognosis for return to pre-injury athletic function. Penetration of the central sulcus of the frog and distal phalanx involvement are associated with euthanasia during hospitalisation. Delayed referral and hospitalisation are associated with both euthanasia and failure to return to pre-injury athletic function. Breed and more than one surgery are associated with failure to return to pre-injury athletic function. These data may assist veterinary surgeons and owners to make evidence-based decisions when managing cases with synovial involvement following solar foot penetration.

Dynamic compression plate (DCP) fixation of propagating medial condylar fractures of the third metacarpal/metatarsal bone in 30 racehorses: retrospective analysis (1990-2005).

REASONS FOR PERFORMING STUDY: An in-depth review of dynamic compression plate (DCP) fixation of propagating medial condyle fractures of the third metacarpus or metatarsus has not been previously reported. OBJECTIVES: To describe the technique, evaluate short-term outcome and long-term race performance of racehorses that underwent DCP fixation for repair of propagating or spiralling medial condylar fractures of the third metacarpal (McIII) or metatarsal (MtIII) bone. STUDY DESIGN: Retrospective case series. METHODS: The surgical case records of 30 horses with propagating fractures of the medial condyle of McIII or MtIII were reviewed. Medical information included: age, breed, sex, presentation, how injury occurred (racing or training), surgical treatment and post operative complications. Racing information included: starts, top 3 placing and career earnings. RESULTS: Long propagating fractures of the medial condyle of Mc/tIII were identified in 23 Thoroughbred (TB) and 7 Standardbred (STB) racehorses. The fracture spiralled proximally in 22 of 30 cases (73%). Standardbreds had a higher propensity for hindlimb involvement (71%), whereas TBs tended to have more front limb involvement (61%). Twelve of 30 (40%) horses raced post surgery. Career earnings were significantly lower for TB horses with medial condylar fractures; $34,916 when compared with the national average of $60,841 (P≤0.03). Overall, horses having DCP fixation for medial condylar fractures had less starts post surgery (3.1 TBs and 5.8 STBs) compared with the national average (7 TBs and 17.3 STBs) and decreased lifetime starts 13.4 (TBs) compared with 17.3 nationally. CONCLUSIONS: Propagating medial condyle fractures can be repaired with plate fixation to potentially lessen the risk of catastrophic fracture destabilisation and return to racing can be expected in 40% of horses. Further prospective studies are warranted comparing lag screw fixation with DCP fixation for repair of severe medial condylar fractures of the metacarpus/metatarsus.

Comparison of conventional and alternative arthroscopic approaches to the palmar/plantar pouch of the equine distal interphalangeal joint.

REASONS FOR PERFORMING THE STUDY: The conventional arthroscopic approach to the palmar/plantar aspect of the distal interphalangeal joint (DIPJ) may result in the inadvertent penetration of the digital flexor tendon sheath (DFTS) and the navicular bursa (NB). This iatrogenic communication would be undesirable subsequent to arthroscopic lavage of a septic DIPJ. HYPOTHESIS: A lateral/medial approach to the palmar/plantar aspect of the DIPJ will result in a significantly lower rate of inadvertent penetration of the DFTS and NB, whilst still providing adequate intra-articular evaluation. METHODS: The conventional palmar/plantar approach or a novel lateral/medial approach to the DIPJ was performed on cadaver fore- and hindlimbs (30 limbs/approach). Subsequently, India ink was injected into the dorsal pouch of the DIPJ, and the DFTS (n = 60) and NB (n = 20) were examined for the presence/absence of ink. In addition, observations of the number of attempts made to access the joint, evidence of iatrogenic intra-articular trauma and occurrence of incomplete visualisation of the palmar/plantar pouch were recorded. RESULTS: With the conventional approach, DFTS penetration was noted in 18/30 (60%) of the limbs, compared to 1/30 (3.3%) with the lateral/medial approach (P≤0.001). NB penetration was seen in 5/10 limbs with the palmar/plantar approach compared to 0/10 with the lateral/medial approach (P = 0.01). No significant differences were found between the approaches in the number of attempts made to access the joint, the incidence of iatrogenic intra-articular trauma, or the occurrence of incomplete visibility of the palmar/plantar pouch. CONCLUSIONS: The novel lateral/medial approach to the DIPJ significantly decreases the risk of inadvertent penetration of the DFTS and NB. POTENTIAL RELEVANCE: The novel lateral/medial approach to the DIPJ is an effective technique to gain access to the palmar/plantar pouches, and is particularly advantageous for arthroscopic lavage of a septic DIPJ.

Extraction of cheek teeth using a lateral buccotomy approach in 114 horses (1999-2009).

REASON FOR PERFORMING THE STUDY: There are few published data regarding the success rates of cheek tooth (CT) removal by lateral buccotomy in the horse. OBJECTIVES: A retrospective study of 114 horses admitted to 2 private equine referral hospitals over a 10 year period (1999-2009), which underwent CT removal via a lateral buccotomy. METHODS: Hospital records were analysed and details including case details, presenting complaint and results of all diagnostic tests and surgical reports were documented. Information obtained during post operative reassessment was also available for analysis. Long-term follow-up information (>2 months) was obtained for 112 horses. RESULTS: Short-term complications (<2 months) occurred in 24/77 horses (31%) undergoing exodontia of the maxillary CT and 10/37 horses (27%) involving mandibular CT, with the majority arising from partial wound dehiscence and infection following 16 extractions (47%). All healed well by second intention. Other complications included both temporary (n = 6) and permanent (n = 3) facial nerve paralysis, myositis (n = 4) and the inadvertent establishment of an oroantral fistula (n = 4). One myositis case was subjected to euthanasia 24 h post operatively. Five horses had persistent sinusitis following surgery due to dental remnants (n = 2) and excessive packing material (n = 1) found in the sinuses. No inciting cause could be found in the remaining 2 horses. One further horse suffered a fatal cardiac arrest at induction of anaesthesia. Of all horses, 92% operated on had returned to their previous level of work after >2 months with no complications. CONCLUSION: Horses with CT removal by a lateral buccotomy have a reasonable prognosis for long-term outcome. POTENTIAL RELEVANCE: Performing a lateral buccotomy is a justified treatment alternative for the surgical removal of equine CT following unsuccessful attempts by standing oral extraction, offering advantages over alternatives such as retropulsion, endodontic therapy and periapical curettage.

Retrospective study of scintigraphic and radiological findings in 21 cases of enostosis-like lesions in horses.

Records of horses admitted to a veterinary surgery in the UK for lameness investigation during 2000 to 2008 were reviewed. Twenty-one horses were identified with both scintigraphic and radiological evidence of enostosis-like lesions (ELLs), in which 68 individual foci of increased radiopharmaceutical uptake were confirmed in 57 long bones. The presenting lameness was attributed to ELLs in 15 of 21 (71 per cent) horses; the remainder were thought to be incidental findings. Five horses were subjected to a repeat examination, four of which showed the occurrence of new lesions in the same or different limbs. Hindlimbs had significantly more lesions than forelimbs, but there was no difference between the right and left limbs. All 18 horses for which follow-up information was available were treated conservatively and returned to soundness after a variable period of time. Following ELL resolution, thoroughbred horses performed at a similar level to that before investigation and diagnosis.

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.

Arthroscopic removal of fractures of the lateral malleolus of the tibia in the tarsocrural joint: a retrospective study of 13 cases.

There is limited information on the treatment of lateral malleolus (LM) fractures in the horse, with no previously published case series for the outcome following arthroscopic removal of such fractures. This report reviews and evaluates findings of a retrospective study of 13 horses admitted to a private equine referral hospital over a 10 year period (1999-2009) that underwent arthroscopic removal of fractures of the LM. Hospital records were reviewed and details including patient history, aetiology of the fracture and limb affected, results of all diagnostic tests and surgical reports were documented. Performance information concerning Thoroughbred horses that went onto race post operatively was collected using an online database. Owners and trainers were contacted regarding the return to performance for non-Thoroughbred cases or those that did not go onto race post operatively. Of the 13 horses presented, 12 were Thoroughbreds, 9 of which were National Hunt racehorses and 3 were Flat racehorses. The other horse in the study was used for general purpose riding. All cases presented with an acute unilateral fracture. Eleven of the 13 had >6 months post operative follow-up and all were nonlame. Of the 12 Thoroughbreds, 10 have raced again, a total of 104 times (median 5 times). The median time from surgery to return to racing was 241 days (180-366 days). It is concluded that horses with fractures of the LM have an excellent prognosis for return to full athletic performance following arthroscopic debridement; and that arthroscopic fragment removal is an appropriate treatment method for fractures of the LM.

An investigation of the relationship between race performance and superficial digital flexor tendonitis in the Thoroughbred racehorse.

REASONS FOR PERFORMING STUDY: There is limited information regarding the number of races and the period for evaluation of outcome which is critical for assessment of SDF tendonitis treatments. OBJECTIVE: To evaluate the re-injury rate and racing performance of Thoroughbred racehorses that sustain SDF tendonitis in relation to matched controls in terms of number of races post treatment and maximum racing performance ratings before and after injury. STUDY DESIGN: Clinical records and racing histories of 401 racehorses with a first occurrence of SDF tendonitis diagnosed by ultrasonography. Controls were of the same age, sex and were horses training in the same establishment at the time of injury as the case horses and where the trainer reported that the horse had not had a previous SDF tendon injury or treatment. RESULTS: Eighty percent of both case and control horses returned to racing after the date of injury, and the re-injury proportion within 3 years of treatment was 53%. The difference in Racing Post Rating((max)) (RPR((max))) and the Racing Post Rating in the race immediately before the treatment date was significantly smaller in case horses (mean = 9.6 lbs; range = 0-75) compared to control horses (mean = 17.0 lbs; range = 0-79). No significant decrease in RPR((max)) was noted post injury. No difference between case and control horses was found for return to racing and racing 3 times, but control horses were significantly more likely to compete 5 races post treatment date than case horses. CONCLUSION AND CLINICAL RELEVANCE: Injury was associated with an individual's pre-injury maximum performance level and return to racing and completion of 3 races are not useful indicator of the outcome of horses with SDF tendonitis. The assessment of the outcome of horses with an SDF injury in a population of racehorses using the number of races post injury requires a minimum of 5 races post injury to be a useful indicator. Further, a re-injury proportion in a population of horses in training for 3 years post treatment.

The use of race winnings, ratings and a performance index to assess the effect of thermocautery of the soft palate for treatment of horses with suspected intermittent dorsal displacement. A case-control study in 110 racing Thoroughbreds.

REASONS FOR PERFORMING THE STUDY: There have been no reports of the efficacy of thermocautery of the soft palate (TSP) assessed objectively as a treatment of intermittent dorsal displacement of the soft palate (DDSP). OBJECTIVE: To compare: racing performance of horses that underwent thermocautery of the soft palate with matched controls; and 'Racing Post ratings' (RPR) with prize money won (RE) and a performance index (PI) for each of the horses in the study. HYPOTHESIS: Thermocautery of the soft palate has no beneficial effect on racing performance and the 3 measures of performance are significantly related. METHODS: The inclusion criteria were fulfilled by 110 horses and each was matched with 2 controls. Changes in performance were compared statistically. RPR, RE and PI were analysed using a regression model. RESULTS: The percentage of horses that improved in performance following the procedure was 28-51% for the 3 measures of performance, compared to 21-53% for the matched controls. There was no significant effect of the procedure on the changes in RPR or RE. There was a significant effect of the procedure on the change in PI (P=0.015) with more treated horses achieving an improved PI and fewer acquiring a worse PI than matched control horses. The measures of performance showed significant correlation. CONCLUSIONS: Thermocautery of the soft palate alone may not be the most efficacious treatment of DDSP. POTENTIAL RELEVANCE: Production of a reliable measure of racehorse performance may be possible.

Outcome of lag-screw treatment of incomplete fractures of the frontal plane of the radial facet of the third carpal bone in horses.

AIM: To describe outcomes for horses diagnosed with incomplete, non-displaced fractures of the frontal plane of the radial facet (INFR) of the third carpal bone (C3) treated by placement of a lag screw across the fracture under arthroscopic guidance. METHODS: Horses (n=13) diagnosed with INFR and treated between December 1999 and January 2005 using a lag screw placed over the fracture were studied. For each case, five horses matched for sire, age and sex which were not known to have INFR were sought for comparison. Racing performance data were collected from a commercial online database. The racing performance of cases pre- and post-operatively, and of cases and matched horses in the post-operative period was compared. RESULTS: Sixteen INFR were found in the 13 horses. Radiographic evidence of healed fracture lines 2-4 months after surgery was seen in 11/16 (69%) fractures; 11/13 (85%) cases raced again after a median recovery period of 292 (range 149-681) days. Treatment was considered successful in 9/13 (69%) cases, which were still in training or had been retired for reasons other than lameness localised to the middle carpal joint at the end of the study period. Just 6/13 (46%) cases had raced prior to injury. The racing ability pre- and post-operatively of five cases was compared, three (60%) of which performed better post-operatively than they had before. There was no significant difference in racing longevity or ability post-operatively between patients and matched (control) horses. CONCLUSIONS: Post-operatively, there was little difference in the racing performance between horses diagnosed with INFR which had a lag screw placed across the fracture line and horses matched for sire, age and sex which were not known to have INFR. CLINICAL RELEVANCE: Horses which were diagnosed with INFR of C3 and had a lag screw placed across the fracture had a good prognosis for future racing performance.

Dynamic obstructions of the equine upper respiratory tract. Part 1: observations during high-speed treadmill endoscopy of 600 Thoroughbred racehorses.

REASONS FOR PERFORMING STUDY AND OBJECTIVE: To review the prevalence of single and complex forms of dynamic airway obstructions within a large group of Thoroughbred horses in training referred for investigation of poor performance. METHODS: Video-endoscopic recordings of the upper respiratory tract made during a standardised treadmill exercise test of 600 Thoroughbred racehorses were reviewed and analysed in real time and slow motion to identify dynamic collapse by the tissues bordering onto the pharyngeal and laryngeal airways. RESULTS: Dynamic collapse within the nasopharynx or larynx was confirmed in 471 of the 600 horses. Dorsal displacement of the soft palate (DDSP; 50%) and palatal instability (33%) were the disorders most frequently identified. It was concluded that deglutition is not a significant event in the triggering of DDSP. Complex forms of dynamic collapse were present in 30% of the horses with upper respiratory tract obstructions. A significant influence of age on the prevalence of DDSP and dynamic laryngeal collapse was identified. There was an increased risk of DDSP in younger horses, and of laryngeal collapse in older horses. No association with gender or format of racing was identified. CONCLUSIONS AND POTENTIAL RELEVANCE: Palatal instability and DDSP comprised the most frequently encountered forms of dynamic collapse within the upper respiratory tract of the Thoroughbred racehorses in this study and are probably expressions of the same nasopharyngeal malfunction. Complex obstructions, i.e. where more than one structure collapses into the airway, occur frequently and therefore treatments that address solitary disorders may often be unsuccessful. Younger horses were found to be at greater risk of sustaining DDSP while older horses seemed more at risk to vocal cord collapse but not to collapse of the arytenoid cartilage itself.

Dynamic obstructions of the equine upper respiratory tract. Part 2: comparison of endoscopic findings at rest and during high-speed treadmill exercise of 600 Thoroughbred racehorses.

REASONS FOR PERFORMING STUDY: The reliability of diagnoses of obstructive conditions of the upper respiratory tract (URT) based on examinations performed at rest vs. at exercise is controversial. OBJECTIVE: To compare diagnosis of URT by endoscopy at rest with that achieved during high-speed treadmill exercise (HSTE). HYPOTHESIS: Endoscopy of URT at rest, when performed in isolation from other simpler techniques is unreliable in the prediction of dynamic respiratory obstructions. METHODS: Endoscopic findings of 600 Thoroughbred racehorses during quiet breathing were compared with findings during high-speed treadmill exercise. Other parameters were also assessed for their specificity in diagnosis. RESULTS: Endoscopy of the resting horse showed low sensitivity (0.15) in the diagnosis of dorsal displacement of the soft palate (DDSP) and palatal instability (PI). When endoscopy and reported noises were taken together there was still a 35% misdiagnosis rate. Although there was significant association between resting laryngeal function score (LFS) and dynamic vocal cord and/or arytenoid cartilage collapse at exercise, 19% of horses with a grade 4/5 LFS were able to attain and maintain full abduction during exercise and 7% of those with 'normal' grades 1 or 2 LFS at rest showed dynamic laryngeal collapse when exerted. Sensitivity of the diagnostic model was greatly increased (80%) when a history of inspiratory noise and palpable intrinsic muscle atrophy were included. CONCLUSIONS AND POTENTIAL RELEVANCE: Endoscopy of the upper respiratory tract of static horses is unreliable in the diagnosis of dynamic obstructions of the URT and should not be used in isolation in surgical decision-making or in the assessment of horses at the time of sale.

Tenoscopic surgery for treatment of lacerations of the digital flexor tendon sheath.

REASONS FOR PERFORMING STUDY: Lacerations to the digital flexor tendon sheath (DFTS) are a common injury in the horse, but little information is available in the literature regarding prognostic indicators. OBJECTIVE: To ascertain whether laceration of the DFTS carried a better prognosis if treated by tenoscopic lavage, debridement and repair within 36 h of the original injury. METHODS: A retrospective analysis of 39 horses treated surgically for lacerations to the DFTS was performed over a 3 year period. The injury-to-surgery interval was recorded as <36 or >36 h. The structures damaged by the injury were also recorded, as well as age, sex, use and outcome. RESULTS: Sixteen horses had laceration and contamination of the DFTS alone, of which 15 (94%) returned to their original or intended use. Sixteen horses had lacerations involving the superficial digital flexor tendon, of which 12 (75%) made a full recovery. Six horses had lacerations to both superficial and deep digital flexor tendons, 5 were subjected to euthanasia intraoperatively and one is paddock sound. Treatment within 36 h of initial laceration carried a significantly better prognosis for return to intended athletic use (25 of 28 horses allowed to recover from anaesthesia) than treatment after 36 h (2 of 5 P = 0.03; Fisher's Exact Test). CONCLUSIONS: If sepsis is treated early using tenoscopic visualisation, lavage and repositol antibiotics, the limiting factor in return to athletic function is tendon damage. POTENTIAL RELEVANCE: This study supports anecdotal evidence that early treatment of synovial sepsis improves the prognosis for return to intended use. It also provides information on prognostic indicators including extent of damage to collateral structures.

Assessment of the efficacy of composite surgery for the treatment of dorsal displacement of the soft palate in a group of 53 racing Thoroughbreds (1990-1996).

REASONS FOR PERFORMING STUDY: There has been no objectively assessed case-control study of the efficacy of surgery to correct dorsal displacement of the soft palate (DDSP) previously reported. HYPOTHESIS: Composite surgery has a beneficial result on racing performance in horses affected with DDSP as compared to a matched control population. METHODS: Race records were obtained for 53 racing Thoroughbreds which underwent composite staphylectomy, sternothyrohyoideus myectomy and ventriculectomy for correction of idiopathic DDSP at the University of Bristol between 1990 and 1996. Each surgical case was matched for age, sex and training yard with 2 control horses. The racing performance, based on prize money won, of surgical cases and control horses were compared for 3 races run before and after the date of surgery. RESULTS: Ninety-two percent of the surgical cases returned to racing after surgery. There was a significant increase in earnings of the surgical group before and after surgery (P = 0.011), but there was no significant difference in earnings of the control group before and after the date of surgery (P = 0335). Sixty percent of the surgical group had higher earnings after surgery than before, compared to 40% of controls. When horses which underwent surgery were ranked relative to their 2 matched controls, surgical cases did not significantly change in rank (P = 033), whereas control horses significantly decreased in rank (P = 0.012). Additionally, horses within the surgical group were more likely (P < 0.01) to start in 3 post operative races than those in the control group. CONCLUSIONS AND POTENTIAL RELEVANCE: Composite surgery had a beneficial effect on racing performance of horses afflicted with idiopathic DDSP, and further studies to evaluate objectively the usefulness of other surgical techniques are warranted.