Multicentre study investigating return to athletic function following synovial sepsis in horses.

Multicentre study investigating return to athletic function following synovial sepsis in horses. | Authorea try { document.documentElement.classList.add('js'); } catch (e) { } var _gaq = _gaq || []; _gaq.push(['_setAccount', 'G-8VDV14Y67G']); _gaq.push(['_trackPageview']); (function() { var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true; ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s); })(); Skip to main content Preprints Collections Wiley Open Research IET Open Research Ecological Society of Japan All Collections About About Authorea FAQs Contact Us Quick Search anywhere Search for preprint articles, keywords, etc. Search Search ADVANCED SEARCH SCROLL This is a preprint and has not been peer reviewed. Data may be preliminary. 3 December 2025 V1 Latest version Share on Multicentre study investigating return to athletic function following synovial sepsis in horses. Authors : Therese De Souza , Elise Rodden 0009-0000-1564-048X [email protected] , Sarah Freeman 0000-0002-3119-2207 , Evita Busschers 0000-0001-8361-5788 , Amelia Cameron 0000-0002-7190-0722 , John Burford 0000-0003-0505-1520 , and Joanna Suthers 0000-0002-3885-7363 Authors Info & Affiliations https://doi.org/10.22541/au.176479396.62658950/v1 280 views 117 downloads Contents Abstract Information & Authors Metrics & Citations View Options References Figures Tables Media Share Abstract Background: Synovial sepsis is a potentially life-threatening and career-ending condition in horses. While survival rates now carry a generally favourable prognosis, there is limited data on return to athletic function (RTF) and the influencing factors. Objectives: To determine the likelihood of adult horses resuming their pre-operative work level or higher following synovial lavage to treat septic synovial structures and to identify factors influencing this outcome. Study design: Multicenter, prospective observational trial. Methods: Data was collected from horses undergoing surgical lavage of septic synovial structures during a 15-month recruitment period. Structured client interviews were conducted a minimum of 365 days after surgery to assess long-term RTF. A comprehensive dataset including horse demographics, clinical presentation, perioperative management, and surgical techniques and findings were recorded. Descriptive statistics, univariable and multivariable logistic regression models were used to identify influencing factors. Results: RTF was achieved in 77.8% (161/207) of horses that survived surgery. Multivariable logistic regression model identified four significant predictors negatively impacting athletic function: increasing horse bodyweight (p=0.041, CI 0.150-0.963), number of surgical procedures (p=0.002, CI 0.059-0.517), volume of lavage fluids used at surgery (p=0.011, CI 0.842-0.977) and the use of postoperative intravenous regional limb perfusion (IVRLP) (p=<0.001, CI 0.072-0.487). Overall 65% (30/46) of horses that did not RTF were due to reasons directly attributable to synovial sepsis and a further 15% (7/46) potentially related. Main limitations: Owner recall bias, incomplete data, small subgroup sizes, and subjectivity in defining RTF. Conclusions: Horses undergoing synovial lavage for treatment of synovial sepsis had a good prognosis for RTF. Variables negatively impacting this outcome were increasing horse bodyweight, number of surgeries, volume of lavage fluids used during surgery and postoperative IVRLP. These findings can assist clinicians and owners with prognostic information to guide decision making and establish expectations. Multicentre study investigating return to athletic function following synovial sepsis in horses. Summary Background: Synovial sepsis is a potentially life-threatening and career-ending condition in horses. While survival rates now carry a generally favourable prognosis, there is limited data on return to athletic function (RTF) and the influencing factors. Objectives: To determine the likelihood of adult horses resuming their pre-operative work level or higher following synovial lavage to treat septic synovial structures and to identify factors influencing this outcome. Study design: Multicenter, prospective observational trial. Methods: Data was collected from horses undergoing surgical lavage of septic synovial structures during a 15-month recruitment period. Structured client interviews were conducted a minimum of 365 days after surgery to assess long-term RTF. A comprehensive dataset including horse demographics, clinical presentation, perioperative management, and surgical techniques and findings were recorded. Descriptive statistics, univariable and multivariable logistic regression models were used to identify influencing factors. Results: RTF was achieved in 77.8% (161/207) of horses that survived surgery. Multivariable logistic regression model identified four significant predictors negatively impacting athletic function: increasing horse bodyweight (p=0.041, CI 0.150-0.963), number of surgical procedures (p=0.002, CI 0.059-0.517), volume of lavage fluids used at surgery (p=0.011, CI 0.842-0.977) and the use of postoperative intravenous regional limb perfusion (IVRLP) (p=<0.001, CI 0.072-0.487). Overall 65% (30/46) of horses that did not RTF were due to reasons directly attributable to synovial sepsis and a further 15% (7/46) potentially related. Main limitations: Owner recall bias, incomplete data, small subgroup sizes, and subjectivity in defining RTF. Conclusions: Horses undergoing synovial lavage for treatment of synovial sepsis had a good prognosis for RTF. Variables negatively impacting this outcome were increasing horse bodyweight, number of surgeries, volume of lavage fluids used during surgery and postoperative IVRLP. These findings can assist clinicians and owners with prognostic information to guide decision making and establish expectations. Introduction Synovial sepsis is a relatively common and potentially life threatening and career-ending condition in horses. While survival rates reported in the literature range from 44% to 90%, 1-4 more recent and larger studies suggest a favourable prognosis, with this data set having a long-term survival rate of 89%. 5 However, the likelihood of a horse returning to athletic function (RTF) following synovial sepsis remains highly variable. This variability is influenced by several factors, including differences in study design, case populations, and methods of outcome assessment. Notably, some studies include both adult horses and foals, despite the differing pathophysiology. Previous retrospective studies have reported that foals generally have poorer long-term outcomes compared to adult horses following synovial sepsis treatment. 6,7 The pre-injury workload and intended use also influences outcomes. Furthermore, the definition of RTF and the duration of follow up is inconsistent, with some studies relying on owner follow-up while others use objective performance data such as racing records. A key distinction highlighted in the literature is whether studies include all horses that survive surgery, horses that survive to hospital discharge or only those that get the opportunity to return to some level of work. These approaches address fundamentally different clinical questions and cannot be directly compared. This difference is reflected in the RTF rates, which range widely from 36% to 100%. 1,3,6-12 Within the literature there has only been one large prospective study analysing just adult horses and this contained a very specific population of just blackthorn penetrations. 8 There remain several controversial variables for which studies have shown conflicting effects on outcomes. These include the duration of sepsis prior to treatment, whether surgery was performed out-of-hours (OOHs), the use of intravenous regional limb perfusion (IVRLP), the specific synovial structure involved, the administration of intrasynovial corticosteroids, the extent of osseous or soft tissue involvement, and the degree of pannus formation, among others. 13 The high cost of treatment and the expectation for horses to RTF highlights the importance of accurately predicting outcomes. Although survival rates following synovial sepsis are generally favourable, the broad variability in RTF rates makes prognosis in individual cases difficult. To improve clinical decision making and support informed discussions with owners, there is a need for large-scale, prospective studies focusing exclusively on adult horses. The objectives of this multicentre study were to determine the likelihood of adult horses resuming their pre-operative work level or higher following synovial lavage to treat septic synovial structures and to identify factors influencing this outcome. The study aimed to provide clinicians and owners with prognostic information to guide decision making and establish expectations. MATERIALS AND METHODS Case selection A prospective multicentre study evaluating outcomes following treatment for synovial sepsis was conducted across ten UK referral hospitals with focus on RTF. The recruitment of hospitals and case selection was as described by Author et al. (2024). 5 The previous study reported survival to discharge and long-term survival. The current study investigated owner reported outcomes related to RTF. Data collection A comprehensive dataset was collected for each case, as described previously by Author et al. (2024). 5 A structured client interview was developed to investigate long-term survival and RTF (Data S1), conducting the interviews following hospital discharge from owners and/or referring veterinarians at a minimum of 365 days post hospital discharge. Information was gathered regarding the current use and pre-injury use of the horse, ownership, death or sale, reasons for reduced athletic performance, any pre-existing performance issues, duration of rehabilitation, and any current medications. All horses remained in the study until death or loss to follow-up. Horses were considered lost to follow-up if there was no response after a minimum of three contact attempts. The structured client interview follow up was conducted by the primary researcher [blinded for review] at nine hospitals, and by in-house veterinarians at one hospital. The study design and protocol was reviewed and approved by [blinded for review]. Informed client consent was required for participation within the study. Statistical analysis IBM SPSS Statistics for Windows (version 29.0.2.0) was used for data collection and analysis. Prior to further analysis, variables were assessed, and appropriate biological grouping performed. Descriptive statistics for all variables were performed and the outcome RTF was categorised as either yes or no. Cases were censored if they were lost to follow up. Continuous and categorical data with a p value for inclusion in a multivariable model. 14 Before inclusion, continuous variables were assessed for whether they met the assumption of linearity and if not, transformations were applied. Linearity was restored in all cases. Independence among variables was assessed using Chi-square tests, Pearson’s correlation, the Mann-Whitney U test or Kruskal-Wallis test where appropriate, p <0.05 was considered a significant association. A manual iterative logistic regression model was conducted in a forwards stepwise fashion, with variable inclusion and subsequent exclusion examined using changes in -2 log likelihood values (-2LL). Statistical significance was set at p 10), and model fit assessed with Hosmer–Lemeshow goodness-of-fit ( p >0.05 indicating good fit) alongside Nagelkerke tests. 15 Delta betas and Cook’s leverage scores were calculated to assess for any influential outliers which were retained unless evidence of potential errors or spurious data were identified (Data S2). Results A total of 240 horses were treated surgically at the referral hospitals during the recruitment period for which the previous study has reported population demographics, surgical treatments and perioperative management. 5 This study reports data for the subset of 207 cases in which long-term follow up was available (Data S3). Thoroughbreds or Thoroughbred crosses predominated the study cohort (38.6%, 80/207), followed by Irish Sport Horses (22.2%, 46/207) and Warmbloods or Warmblood crosses (15.9%, 33/207). The median weight was 523kg (range 175-786kg) and performance or competition, including racehorses, was the most common pre-injury use in 38.6% (80/207) of cases. General purpose made up 17.4% (36/207) of cases, hunting 15.9% (33/207), unknown 9.7% (20/207) and other 18.4% (38/207). The ‘other’ category primarily consisted of youngstock but also contained retired horses and broodmares. The metacarpophalangeal or metatarsophalangeal joints were the most frequently affected (20.3%, 42/207), followed by the digital flexor tendon sheath (18.8%, 39/207) and then the carpal joints (13.5%, 28/207). Wounds were identified in 71.0% of cases (147/207), foreign bodies detected in 20.3% (42/207), and blackthorn penetrations accounted for 14.0% (29/207) of the total cases. Antimicrobials and non-steroidal anti-inflammatories were administered prior to referral in 42.3% (77/182) and 37.8% (68/180) of cases, respectively. A culture and sensitivity sample was submitted in 38.2% (79/207) cases but there were missing data for 104 cases. From these samples 69.6% (55/79) had a positive culture. There were just eight cases (8/207) of iatrogenic synovial sepsis and two of these were post intrasynovial injection and one post arthroscopy. The other five cases had insufficient data recorded. The duration of suspected synovial sepsis prior to treatment varied, with 26.1% (54/207) of cases presenting within 12 hours and 15.0% (31/207) after more than 7 days (Figure 1). Figure 1 : A bar chart showing the percentage of horses returning to athletic function following synovial lavage grouped by duration of synovial sepsis prior to referral, from a multicentre UK study investigating outcomes of synovial sepsis. The bar chart displays the proportion of horses that returned to athletic function (light blue bars) versus those that did not (dark blue bars) across four time intervals based on the duration of sepsis prior to referral: 7 days (n=31). Return to athletic function remained high across all time groups, with the highest percentage observed in horses referred between 1 and 7 days after onset. Delayed referral (>7 days) was associated with a higher proportion of horses not returning to athletic function but this was not found to be statistically significant. Surgeries were performed within working hours in 78.7% (163/207) cases. Intraoperatively, the median volume of lavage fluid used was 10 litres (range: 2–29 litres), and this was not statistically associated with the specific synovial structure being lavaged. Synovial inflammation was classified as none to mild in 52.7% of cases (109/207) and moderate to severe in 26.1% of cases (54/207), with data unavailable for 44 cases. Pannus was classified as none or mild in 56.0% of cases (116/207), and as moderate to severe in 25.1% of cases (52/207) (Data S3). Osseous pathology was only present in 16.9% (35/207) of cases and soft tissue pathology present in 22.2% (46/207) of cases (Table 1). Intrasynovial antimicrobials were administered during surgery in 93.7% (194/207) cases with amikacin being most used, when specified. Just 13% (27/207) of horses had more than one surgery (Figure 2). IVRLP was primarily used postoperatively, with only two cases receiving intraoperative treatment compared to 27.5% (57/207) postoperatively. Half of the horses received a single postoperative IVRLP treatment, while the other half received two or more. Gentamicin was the antimicrobial of choice, used in 87.3% (48/55) of cases, followed by amikacin (5/55) and ceftiofur (2/55). Table 1: Surgical factors and percentage returning to athletic function from a multicentre UK study investigating outcomes following treatment of synovial sepsis in the horse. (n) (%) When surgery was performed Out of hours 44 31 70 Working hours 163 130 80 Not recorded 0 Osseous pathology Present 35 25 71 Not present 160 125 78 Not recorded 12 Cartilage pathology Present 27 21 78 Not present 139 110 79 Not recorded 41 Soft tissue pathology Present 46 33 72 Not present 114 90 79 Not recorded 47 Pannus (scale at surgeon’s discretion) None 60 45 75 Mild 58 50 86 Moderate 24 19 79 Severe 28 21 75 Not recorded 37 Synovial inflammation 1.Hyperaemia 2.Petechiation 3.Proliferation 4.Stunting None (0/4) 48 36 75 \tightlist Mild (1/4) 62 50 81 Moderate (2-3/4) 35 25 71 Severe (4/4) 20 17 85 Not recorded 42 Foreign body Present 42 33 79 Not present 132 105 80 Not recorded 33 Figure 2: A flow diagram showing the number of surgical procedures each horse underwent and how this affected return to athletic function, from a multicentre UK study investigating outcomes of synovial sepsis in the horse. Figure Legend: This flow diagram illustrates outcomes following one, two, or three surgical lavages in 207 cases of synovial sepsis. After the first lavage, 71% (146/207) of horses returned to athletic function, while 48% (13/27) that underwent a second surgery returned to athletic function, and 40% (2/5) undergoing a third surgery returning to athletic function. The diagram shows a decreasing trend in RTF rates with each additional surgical intervention. No horses underwent more than three surgeries. RTF= return to athletic function; X RTF = did not return to athletic function; orange= cases that did not return to athletic function; dark blue= horses that did return to athletic function. At 365 days post-surgery, long-term survival was 89.4% (185/207) as previously published using this data set. 5 Of the 207 horses that survived surgery, 11 did not survive to discharge. These cases were all euthanised due to persistent synovial sepsis. RTF was achieved in 77.8% (161/207) horses that survived surgery and this improved to 82.6% (161/195) from horses that survive to discharge. Overall RTF was not achieved in 22.2% (46/207) horses that survived surgery of which 65% (30/46) cases were attributable to reasons relating directly to synovial sepsis and a further seven cases lacked reasoning but some of these are likely to be attributable to synovial sepsis (Figure 3). There were seven cases that did not RTF but for reasons not related to synovial sepsis, most commonly occurring due to concurrent pathology, with one horse retiring due to cataracts. A further two cases were yet to restart work for owner related reasons. Twenty-two horses were euthanised and the most common reasoning being poor response to treatment or persistent lameness attributable to the synovial sepsis. Eleven horses returned to a lower level of performance with all horses having signs of persistent lameness or osteoarthritic changes in the affected synovial structure and one case of reduced range of motion following extensor carpi radialis tendon sheath sepsis (Figure 3). Figure 3: Distribution of contributing factors in horses that failed to return to athletic function following synovial lavage from a multicentre UK study investigating outcomes of synovial sepsis in the horse. Univariable logistic regression analysis highlighted several significant variables affecting the outcome RTF (Table S1 and S2), with four remaining in the final multivariable logistic regression model (Table 2). The significant predictors negatively impacting likelihood of RTF included increasing horse bodyweight ( p =0.041, CI 0.150-0.963), undergoing multiple surgical procedures ( p =0.002, CI 0.059-0.517), increasing volume of fluids used to lavage at surgery ( p =0.011, CI 0.842-0.977) and receiving postoperative IVRLP ( p =<0.001, CI 0.072-0.487). All these predictors were associated with a reduced likelihood of RTF (Data S4). Some of the variables that had no statistical influence on RTF included the preoperative synovial white cell count or total protein, duration of sepsis, whether surgery was performed out of hours, the presence of concurrent osseous pathology, degree of pannus, iatrogenic causes and the synovial structure affected. Apart from three cases of carpal sheath sepsis, distal interphalangeal joint sepsis had the lowest RTF rate of just 38% (5/13) but was not statistically significant. Delayed referral of more than seven days post injury had a higher proportion of horses not RTF but this was not found to be statistically significant (Figure 1). Table 2: Multivariable logistic regression model presenting factors influencing return to athletic function in 207 horses that underwent treatment of synovial sepsis at ten UK referral hospitals (horses that did RTF N= 160, and horses that did not RTF N= 46, from all horses that survived surgery). Lower Upper Number of surgeries -1.745 0.554 0.002 0.175 0.059 0.517 Volume of fluids used for lavage (litres) -0.098 0.038 0.011 0.907 0.842 0.977 Postoperative IVRLP -1.678 0.489 <0.001 0.187 0.072 0.487 Horse bodyweight (kg) -0.966 0.474 0.041 0.381 0.150 0.963 Abbreviations: B= regression coefficients; S.E= standard error; IVRLP= intravenous regional limb perfusion; kg=kilograms Discussion This study highlights a generally favourable prognosis for horses undergoing synovial lavage for synovial sepsis with 78% of horses that survive surgery returning to or exceeding pre-injury work levels. While various studies have examined survival rates following treatment for synovial sepsis, 1-4 factors critical to long-term athletic recovery remain less clear. Multivariable logistic regression analysis revealed four variables that significantly reduced the likelihood of RTF. These included increasing bodyweight of the horse, undergoing multiple surgeries, postoperative IVRLP treatment and the volume of fluids used for lavage. Heavier horses have previously been linked to poorer outcomes and increased mortality following synovial sepsis. 4,6 Increased weight places greater mechanical stress on joints, which may delay healing and promote osteoarthritic changes or exacerbate concurrent pathology. 9,11,12 Evidence from human orthopaedics indicates that obesity is a recognised risk factor for poorer outcomes after surgery, attributable to factors such as increased biomechanical loading and limitations on rehabilitation that can prolong recovery. 16 Unlike horse bodyweight, the remaining three significant variables are likely to be indicators of more complex cases rather than directly negatively impacting RTF. The association between a requirement for multiple surgical interventions and a reduced likelihood of RTF observed in the present study aligns with previous findings in both equine and human literature. 17 Repeated synovial lavage is frequently indicative of incomplete resolution of the initial septic process and ongoing inflammation. Persistent or recurrent infection necessitating additional surgical intervention has been associated with compromised cartilage integrity and an elevated incidence of degenerative joint disease (DJD), a recognised factor limiting long-term performance outcomes in equine athletes. 18 In addition, persistent or recurrent inflammation could result in inflammation of the synovial cavity and thickening of the synovial lining. 19 Multiple procedures can also contribute to cumulative iatrogenic trauma to synovial structures. Although arthroscopic and through-and-through lavage techniques are considered minimally invasive, they nonetheless result in disruption of the synovial lining, and repeated instrumentation may potentiate synovial inflammation and delay tissue healing. 20,21 Horses may demonstrate residual lameness or joint stiffness, thereby impairing their ability to RTF. Similar mechanisms have been documented in human orthopaedics, where repeated joint debridement is associated with poorer functional outcomes in cases of septic arthritis, 22 further supporting this finding in the equine context. Horses that did not receive postoperative IVRLP were more likely to RTF. Although IVRLP is commonly employed as a prophylactic or therapeutic adjunct in the management of synovial sepsis, this finding is likely to reflect selection bias. The use of IVRLP can be clinician dependent, however horses receiving IVRLP are often perceived to have more severe pathology or show a poor response to initial treatment, and it can be preferred over intra-synovial medication when there is concurrent soft tissue or osseous pathology. These associations are inherently thought to carry an inferior prognosis. This is supported by a recent study finding horses treated for synovial sepsis were less likely to survive as the total number of IVRLP treatments increased. 23 Increased volumes of lavage fluid used during surgery was also significantly associated with a reduced likelihood of RTF and unsurprisingly corresponded with longer anesthesia durations. This likely reflects the need for more extensive lavage in cases with complex or severe intra-synovial pathology. While previous research has identified marked pannus and osseous pathology as negative prognostic factors linked to decreased survival and postoperative performance, 3,6,8 our study did not observe these associations. It is important to note that only a limited number of cases exhibited concurrent osseous pathology, and data regarding the severity of pannus at surgery was incomplete, which may have impacted our findings. Due to the low numbers in more specific categories, the presence of osseous and soft tissue pathology was analysed only as a binary yes/no outcome, without further characterisation or detail regarding the specific injuries which would also impact the results. No significant association was found between the type of surgical procedure, surgical approach, or the specific synovial structure affected and the likelihood of RTF. Most cases (94.1%) underwent endoscopic lavage, with only a small number managed using through-and-through needle lavage (5.8%), and just one case via an open approach. The latter case did not RTF, although the sample size is too small to draw definitive conclusions. Open synovial approaches, while occasionally necessary for specific anatomical locations or severe contamination, are associated with increased morbidity, postoperative fibrosis, and greater postoperative care. 24 Their rare use in this study likely reflects a broader shift in surgical practice toward minimally invasive techniques. The distal interphalangeal joint (DIPJ) exhibited a notably low return to athletic function rate (38%, 5/13), although this was not statistically significant. The lack of statistical significance may reflect limited numbers and statistical power rather than a true absence of association. Only the carpal sheath showed a lower RTF rate based on just three cases, which limits interpretation. A previous study reporting outcomes following synovial sepsis surgery for foot penetrations also reported a much lower RTF rate of 36%, 3 however only four out of our 207 cases involved foot penetrations, limiting the ability to draw robust conclusions for this subset. Given that a poor prognosis for DIPJ sepsis has been suggested in previous studies, 25,26 this trend warrants further investigation in a larger cohort to determine whether the low RTF rate observed here reflects a true prognostic difference. Delayed treatment has previously been linked to worse outcomes in the literature, 27,28 however our study found no statistically significant association between duration of sepsis and RTF. This aligns with many other studies that also found no association. 4,7,10,11,24,25 Advancements in perioperative protocols, such as earlier antimicrobial administration and improved pre-referral stabilisation may have lessened the clinical impact of delayed surgery compared to earlier reports. A key contributing factor is case selection bias as severely affected horses referred late may have been euthanased before surgical treatment. These cases would have been excluded from the study meaning worse outcomes would be underrepresented. There is a slight trend in the cases presenting more than seven days from initial injury having a decreased RTF, however this finding did not achieve statistical significance (Figure 1). In our cohort, the majority of OOHs procedures were performed by only two of the ten participating referral centres. This uneven distribution introduces a potential confounding factor and limits the generalisability of our findings regarding the impact of surgical timing. These centres may have had more robust OOHs staffing models, mitigating the negative outcomes previously associated with OOHs surgery. 2 The culture-positive rate in this study was 69.6%, higher than figures reported in several previous studies (typically around 30–50%). 3,8 Despite this relatively high positivity rate, no association was found between culture status and RTF. However, knowledge of the pathogen and antimicrobial susceptibility may still influence clinical decisions and outcomes, particularly in resistant or atypical infections and also supports rational for antimicrobial selection and responsible use. Many studies acknowledge poorer outcomes in iatrogenic cases of synovial sepsis when corticosteroids have been used, whether it is from clinical impression or from data. 29,30 Due to low numbers, these findings are often mentioned without strong statistical validation . There were eight cases of iatrogenic synovial sepsis in this cohort, with incomplete data for five cases and so further research is still needed in this area. The role of financial constraints in clinical decision-making can also not be overstated. In this study, several early euthanasias occurred not due to a poor prognosis per se, but because the owners were unable or unwilling to fund continued treatment or a second surgery. These horses may have otherwise been viable candidates for recovery and this is an important source of potential bias in both survival and RTF data. Acknowledging this limitation is essential when interpreting outcome data and setting realistic expectations with owners at the time of diagnosis. This study demonstrates horses undergoing synovial lavage for treatment of synovial sepsis have a good prognosis for RTF and highlights several factors identified as significantly associated with a reduced likelihood of RTF. These included increasing horse bodyweight, multiple surgical interventions, postoperative IVRLP and a higher volume of fluids used for lavage. Apart from bodyweight of the horse, the other variables are likely secondary findings from cases with more complex pathology and so future studies with more cases reporting concurrent osseous or soft tissue pathology and degree of pannus would be recommended. Combining RTF with an objective lameness assessment would also be useful to remove the subjectivity around the term ‘return to athletic function’ and the potential for owner bias. However, the findings from this study do provide clinicians and owners with prognostic information to guide decision making and establish expectations. References 1. Wright I, Smith M, Humphrey D, et al. Endoscopic surgery in the treatment of contaminated and infected synovial cavities. Equine Vet J. 2003;35:613–619. 2. Milner P, Bardell D, Warner L, et al. Factors associated with survival to hospital discharge following endoscopic treatment for synovial sepsis in 214 horses. Equine Vet J. 2014;46:701–705. 3. Findley J, Pinchbeck G, Milner P, et al. Outcome of horses with synovial structure involvement following solar foot penetrations in four UK veterinary hospitals: 95 cases. Equine Vet J. 2014;46:352–357. 4. Rubio-Martínez L, Elmas C, Black B, et al. Clinical use of antimicrobial regional limb perfusion in horses: 174 cases (1999–2009). J Am Vet Med Assoc. 2012;241:1650–1658. 5. [blinded for review] 6. Crosby D, Labens R, Hughes K, et al. Factors associated with survival and return to function following synovial infections in horses. Front Vet Sci. 2019;6:367. 7. Smith L, Mellor D, Marr C, et al. What is the likelihood that a horse treated for septic digital tenosynovitis will return to its previous level of athletic function? Equine Vet J. 2006;38:337–341. 8. Ashton N. Prospective study of blackthorn injury and synovitis in 35 horses. Equine Vet Educ. 2020;32:492–499. 9. Duggan M, Mair T. Comparison of outcomes following treatment of septic calcaneal bursitis by needle or bursoscopic lavage: a retrospective study of 29 horses. Equine Vet Educ. 2020;33:135–142. 10. Isgren C, Salem S, Singer E, et al. 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. Equine Vet J. 2020;52:404–410. 11. Walmsley E, Anderson G, Muurlink M, et al. Retrospective investigation of prognostic indicators for adult horses with infection of a synovial structure. Aust Vet J. 2011;89:226–231. 12. Wereszka M, White N, Furr M. Factors associated with outcome following treatment of horses with septic tenosynovitis: 51 cases (1986–2003). J Am Vet Med Assoc. 2007;230:1195–1200. 13. de Souza TC, Suthers JM, Busschers E, et al. A scoping review of the current evidence on treatment and outcomes following synovial sepsis. Equine Vet J. 2022;54:467–480. 14. Menard S. Multiple logistic regression. In: Applied Logistic Regression. 2nd ed. Thousand Oaks: Sage; 2000. p.31–46. 15. Pallant J. SPSS Survival Manual: a step by step guide to data analysis using IBM SPSS. 7th ed. London: McGraw-Hill; 2020. 16. Jiang K, Chen B, Lou D, et al. Systematic review and meta-analysis: association between obesity/overweight and surgical complications in IBD. Int J Colorectal Dis. 2022;37:1485–1496. 17. Walinga AB, Stornebrink T, Emanuel KS, et al. Failure rates in surgical treatment in adults with bacterial arthritis of a native joint: a systematic review of 8,586 native joints. Arch Orthop Trauma Surg. 2023;143:6547–6559. 18. Bertone AL, Palmer JL, Jones J. Synovial fluid cytokines and eicosanoids as markers of joint disease in horses. Vet Surg. 2001;30:528–538. 19. Beccati F, Gialletti R, Passamonti F, et al. Ultrasonographic findings in 38 horses with septic arthritis/tenosynovitis. Vet Radiol Ultrasound. 2015;56:68–76. 20. Stake S, Scully R, Swenson S, et al. Repeat irrigation and debridement for patients with acute septic knee arthritis: incidence and risk factors. J Clin Orthop Trauma. 2020;11:S177–S183. 21. Hunter JG, Gross JM, Dahl JD, et al. Risk factors for failure of a single surgical debridement in adults with acute septic arthritis. J Bone Joint Surg Am. 2015;97:558–564. 22. Mathews CJ, Weston VC, Jones A, et al. Bacterial septic arthritis in adults. Lancet. 2010;375:846–855. 23. Loppnow Z, Kersh K, Wang C, et al. Clinical use of antimicrobial regional limb perfusion in adult horses diagnosed with synovial sepsis or penetrating synovial wounds at a single equine referral hospital in the Midwest United States: 163 cases (2010–2020). Front Vet Sci. 2025;12:1504486. 24. Wright I. Arthroscopic surgery in the management of contamination and infection of joints, tendon sheaths, and bursae. Clin Tech Equine Pract. 2002;1:234–244. 25. Pille F, Martens A, Oosterlinck M, et al. A retrospective study on 195 horses with contaminated and infected synovial cavities. Vlaams Diergeneeskd Tijdschr. 2009;78:97–104. 26. Peek M. Equine Synovial Sepsis – A Systematic Review of the Literature. Biological Sciences Honors Program Honors Thesis. Cornell University; 2022. 27. Schneider R, Bramlage L, Moore R, et al. A retrospective study of 192 horses affected with septic arthritis/tenosynovitis. Equine Vet J. 1992;24:436–442. 28. Fraser B, Bladon B. Tenoscopic surgery for treatment of lacerations of the digital flexor tendon sheath. Equine Vet J. 2004;36:528–531. 29. Lapointe J, Laverty S, Lavoie J. Septic arthritis in 15 Standardbred racehorses after intra-articular injection. Equine Vet J. 1992;24:430–434. 30. Krause DM, Pezzanite LM, Griffenhagen GM, et al. Comparison of equine synovial sepsis rate following intrasynovial injection in ambulatory versus hospital settings. Equine Vet J. 2022;54:523–530. Information & Authors Information Version history V1 Version 1 03 December 2025 Copyright This work is licensed under a Non Exclusive No Reuse License. Authors Affiliations Therese De Souza CVS UK Limited View all articles by this author Elise Rodden 0009-0000-1564-048X [email protected] CVS UK Limited View all articles by this author Sarah Freeman 0000-0002-3119-2207 University of Nottingham - Sutton Bonington Campus View all articles by this author Evita Busschers 0000-0001-8361-5788 Murdoch University View all articles by this author Amelia Cameron 0000-0002-7190-0722 University of Nottingham - Sutton Bonington Campus View all articles by this author John Burford 0000-0003-0505-1520 University of Nottingham - Sutton Bonington Campus View all articles by this author Joanna Suthers 0000-0002-3885-7363 CVS UK Limited View all articles by this author Metrics & Citations Metrics Article Usage 280 views 117 downloads .FvxKWukQNSOunydq8rnd { width: 100px; } Citations Download citation Therese De Souza, Elise Rodden, Sarah Freeman, et al. Multicentre study investigating return to athletic function following synovial sepsis in horses.. 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