TitleUpper appendicular, pelvic and axial skeletal pathology with poor performance

Background: There is very little information available about the health status of young stallions from the German Warmblood population that will, once licensed, shape the future of the equestrian sport and horse-breeding. Objectives: To evaluate the prevalence of clinical findings at licensing examinations of candidate stallions and the influences of season of birth, age at licensing, year of licensing, and the evaluator on the distribution of recorded findings. Study design: Retrospective observational study Methods: Clinical records of 1655 candidate stallions presented for licensing in 2018–2020 were reviewed. Data were provided by all German Warmblood horse-breeding associations and their official veterinarians. Storage and processing of the records was performed using the German equine health database. Generalised linear models were used to determine the influences of fixed effects (season of birth, age at licensing, year of licensing, evaluator) on main clinical findings. Significance level was set at p < 0.05. Results: No remarks were documented on the clinical examination protocol in 777 of the 1655 horses (47.0 %). Furthermore, 51.9% of those stallions with remarks had only one finding documented. Main abnormalities recorded were skin lesions, enlargements on the limbs, and testicular findings. The distributions of several clinical findings differed significantly between the evaluators. Main limitations: Homogenous study population and retrospective data Conclusion: The clinical part of the licensing examination of German Warmblood candidate stallions presented in 2018–2020 revealed mostly no or only very few findings. Furthermore, the majority of the clinical findings recorded are considered to be of minor clinical relevance, implying an overall favourable clinical health status of the stallions presented.

Background: Equine odontoclastic tooth resorption and hypercementosis (EOTRH) is a painful disorder primarily affecting the incisor teeth of horses over 15 years of age. Clinical signs of the disease include mastication problems, halitosis and weight loss. The disease predominately affects the reserve crown and presents as a loss of dental tissue and excessive build-up of cementum. Objectives: Determine the radiographic scores of horses with EOTRH and age-matched controls. Increase understanding of EOTRH using microCT to compare teeth from horses with EOTRH and age matched controls. Methods: This study used radiography ( in vivo) and microcomputed tomography (microCT) ( ex vivo) to help understand and characterise EOTRH. For radiography, 87 patients were assessed using a radiographic scoring system for EOTRH. The microCT study was undertaken on 20 incisor teeth which were scanned and segmented to measure the different dental tissues. These were assessed using a descriptive analysis (surface roughening, tooth resorption, root blunting, pulp cavity). Study design: In vivo and ex vivo studies. Results: Radiographic scoring demonstrated that 03s were more severely affected than 01s in EOTRH. Total radiographic score and age had a weak positive correlation. Following microCT, we identified that EOTRH teeth had a lower pulp and enamel volume and therefore significantly higher ratios relative to the whole tooth volume, compared to control teeth. Cementum and dentine volumes were more variable in EOTRH teeth. Thus, their ratios relative to the whole tooth volume were not different to control teeth. Main limitations: The number of horses was relatively small. Conclusions: Results suggest differing degrees of tooth resorption and hypercementosis, potentially indicating multiple phenotypes of the disease.

Background: There is a shortage of equine veterinarians. Understanding what factors are associated with job satisfaction in equine veterinarians can inform interventions to increase retention in equine medicine. Objective: To explore the prominent factors causing work dissatisfaction and burnout in equine veterinarians. Study design: A qualitative research study was conducted that consisted of semi-structured focus groups. Methods: Thirty-seven current and former equine veterinarians across the United States were recruited via snowball and convenience sampling to answer questions on work history, work-life balance, and perceptions of equine practice. Transcripts were analyzed in Delve and coded in the context of the Conservation of Resources (COR) theory. A card sorting activity was used to rank the four types of resources in the COR theory (condition, object, energy, personal). Results: Condition resources were the most frequently mentioned reasons for work dissatisfaction. These included issues with discrimination or bias due to age, race/ethnicity, and gender, unpredictable and long hours, and heavy workload. Object resources, such as equipment, were rarely mentioned. Energy resources, including pay and student loan debt, were influential, with most participants feeling that equine veterinarians are underpaid. Personal resources, such as problem-solving skills and enjoyment in helping others, improved job satisfaction. Main limitations: Although recruiting efforts prioritized perspectives of black, indigenous, and people of color (BIPOC), lesbian, gay, bisexual, transgender, queer plus (LGBTQ+) identities, and members with disabilities, demographic information was not directly collected. Conclusions: The main barriers to equine veterinary retention included lack of work-life balance, long hours, lower-than-expected pay, and issues with discrimination and bias. This study highlights areas for intervention to improve the equine veterinary field, such as higher pay, rural practice incentives, and effective diversity, equity, inclusion, and belonging (DEIB) efforts. A shift toward caseload-sharing between veterinarians could help alleviate excessive emergency on-call and burnout.

Background Equine dental diseases significantly impact on a horse’s overall health, performance, and quality of life. They can result in secondary infections and digestive disturbances, potentially leading to colic. A recently described disease affecting the incisors of horses is equine odontoclastic tooth resorption and hypercementosis (EOTRH). Understanding EOTRH is crucial for early diagnosis, effective management, and prevention of its severe consequences. Objectives To determine proteomic differences in incisor cementum in horses with and without clinical EOTRH. Study Design Comparative and observational clinical study. Methods Teeth were extracted and cementum was isolated using a diamond wire. Proteins were extracted using an optimised sequential workflow, and trypsin digested for mass spectrometry. Protein identification and label-free quantification was undertaken. Results In total 1149 unique proteins were detected in cementum across all samples. We identified four proteins exclusively in EOTRH affected cementum. EOTRH samples showed a higher heterogeneity than healthy samples. In total 54 proteins were increased in EOTRH, and 64 proteins were reduced (adjusted p-value < 0.05). Inflammatory proteins, such as cathepsin G (p = 0.004), neutrophil elastase (p = 0.003), bactericidal permeability-increasing protein (p = 0.002), azurocidin (p = 0.003) and lactotransferrin (p = 0.002) were all increased in EOTRH. Pathway analysis revealed that antimicrobial peptides (Z score 2.65, p = 1.93E-09) and neutrophil degranulation (Z-score 1.89, p = 1.7E-04) were commonly up-regulated canonical pathways. Main limitations The sample size was limited. Conclusion EOTRH leads to biochemical changes within the cementum proteome, which are important in explaining the physiological changes occurring in disease. Differentially abundant proteins may represent promising biomarkers for earlier disease detection and establishment of a cell-based model could provide further insight into the role these proteins play in hypercementosis.

BACKGROUND: Intervention by hoof care professionals is critical for a functioning equine hoof. Pressure distribution provides information on loading, however information on the effects of such interventions on pressure distribution is lacking OBJECTIVES: To describe the pressure changes of equine fore feet following trimming. STUDY DESIGN: Cross-sectional cohort study METHODS: 50 sound horses were recruited through convenience sampling. 18 external hoof measures of the dorsal, lateral, medial and solar aspects were obtained before and after trimming from 94 fore feet. Horses were walked over a pressure mat before and after trimming and pressure maps of the solar surface created. Percentage change in hoof measures were assessed. Factors associated with an increase in pressure in the frog region after trimming were entered into a forward likelihood ratio logistic regression model. Odd ratios (ORs) with 95% confidence intervals (CI) and area under the curve receiver operator characteristics (AUROC) were calculated. Sensitivity and specificity were calculated at a cut-off value of P=0.5. RESULTS: Trimming resulted in a significant increase in pressure, topographically mapped to the frog region, in 12/94 feet. Percentage difference in bearing border length (OR 0.66 95% CI 0.51; 0.86), heel buttress to centre of pressure distance (OR 1.30 95% CI 1.10; 1.53), heel angle (from the lateral side) (OR 1.11 95% CI 1.04; 1.19) and heel length (from the medial side) (OR 0.92 95% CI 0.85; 0.99) were retained in the final model associated with increased pressure in the frog region following trimming. AUROC was excellent (0.94 95% CI 0.88; 0.99) with fair sensitivity (58%) and excellent specificity (98%) at P=0.5. MAIN LIMITATIONS: Subjective lameness exam only. CONCLUSIONS: Measuring pressure changes over the solar surface of the equine fore foot after trimming identified that an increased pressure in the frog region was linked to specific changes in hoof shape.

Background: Equine obesity is a growing concern, much of the current management advice centres on dietary restrictions, including the removal or limitation of grazing. Little is known about the effectiveness and impact of this approach on the overall welfare of the horse. Objective: This study investigates the impact of two commonly used grazing systems advocated for the control of weight – the ‘strip-grazing’ system and the ‘track’ system - on the behaviour and welfare of outdoor living ponies. Study design: A within-subject cross-over experimental design was used with four groups of pasture kept ponies experiencing each system for 4 weeks in a random order. Methods: Time budgets and behavioural indicators of welfare were measured using 24-hour electronic surveillance, morphometric parameters including weight, body condition score and cresty neck score were measured weekly and activity levels were tracked using GPS tracking units. Results: Ponies moved more (median (IQR), track: 3.23% (2.08%), strip: 2.02% (0.90%); P = 0.001) and travelled a greater distance in 24-hour period (median (IQR), track: 7013.47m (1761.49m), strip: 5331.91m (494.16m); P < 0.001) and engaged in less overt agonistic behaviour on the track system compared with the strip system (median IQR; track: 0.14 (0.30), strip: 0.21 (0.37) P = 0.02). Main Limitations: A relatively short time period of exposure to each grazing system. Conclusions: Track systems resulted in a significant increase in ambulatory behaviour compared with the strip system. Increased levels of agonistic interactions on the strip system maybe the result of perceived reduction of space or a spatial concentration of resources compared to the track system, although the actual accessible area was the same. These results suggest that there may be physical health benefits to the track system as the ponies engaged in more voluntary low intensity exercise as well as improvements to overall welfare.

Background: Equine trigeminal-mediated (TGM) headshaking (HS) is a facial pain syndrome characterised by varying intensity and frequencies of head movements and nasal irritation. An accurate method for quantification and/or characterisation of severity is lacking. Objectives: To develop and validate an objective measure of TGMHS. Study design: Prospective case control study. Methods: Horses presenting for HS were recruited alongside those presenting for forelimb lameness (LAME) and pre-purchase examination as well as healthy controls (CONTROL). Head movement data were collected for five minutes whilst trotting on the lunge using a tri-axial accelerometer (range ±16g, sampling rate of 800Hz) on the bridle headpiece. Recordings were exported and peak detection performed using minimum and maximum thresholds of -1g and +1g (corrected for gravity) and a minimum peak width of 10 samples. Results: Fifty-six horses were included in the study; 18 TGMHS, 10 non-TGMHS, 12 LAME and 16 CONTROL. Characteristics and frequency of vertical (Z axis) head movements of TGMHS horses differed significantly from other horses. TGMHS horses had peaks with greater mean and maximum positive g-force (P<0.005) and lower mean and minimum negative g-force (P<0.001), greater frequency of peaks/min (P<0.001), and over twelve times greater percentage of peaks >+2g compared to other horses (P<0.001). Receiver operator curve characteristics of percentage of peaks >+2g (CI 0.72-0.95), percentage of peaks <-2g (CI 0.66-0.92), and percentage of peaks <-2g and >+2g (CI 0.72-0.96) showed excellent discrimination of TGMHS horses from LAME, CONTROL and non-TGMHS horses. Main limitations: Referral population of horses, small sample size, and control horses were not evaluated for orthopaedic disease. Conclusions: Accelerometer data from trotting exercise on the lunge gives an objective measure of HS and can differentiate between TGMHS, non-TGMHS, normal head movements, and those associated with forelimb lameness. Accelerometer use may aid HS diagnosis and monitoring of management strategies.

Background: Surgical site infection (SSI) is a frequent complication following emergency equine laparotomy. It negatively impacts equine welfare, increases treatment costs and is a hospital biosecurity risk justifying investigations of ways to reduce SSI incidence. Objectives: To determine if a sutured-on stent dressing for anaesthetic recovery reduces SSI in horses following emergency laparotomy. Study design: Randomised controlled trial. Methods: Eligible horses undergoing emergency exploratory laparotomy were enrolled. Horses were randomised to have a sutured-on stent dressing (intervention) or standard adhesive textile dressing (control) placed for incisional protection during anaesthetic recovery. Horses were followed up to 90 days postoperatively. Data were analysed according to intention-to-treat principles. Time to SSI (primary outcome) for each group was analysed using a Cox proportional hazard model. Secondary outcomes (SSI during hospitalisation, pyrexia during hospitalisation, days hospitalisation and incisional hernia formation at 90 days) were analysed using Chi-squared tests and a univariable logistic regression model (categorical data) or by comparing means between groups (continuous data). Results: The study included 352 horses (167 intervention group, 185 control group). SSI developed in 101 horses (28.7%) at a mean of 9.7 days (SD 4.6 days). Rate of SSI was not significantly different between intervention and control groups unadjusted (Hazard Ratio [HR] 0.83, 95% CI 0.56 - 1.23, P=0.36) or adjusted for variables significantly associated with rate of SSI (HR 0.88, 95% CI 0.59 – 1.30, P=0.51). There were no significant differences in secondary outcomes between intervention and control groups. Main limitations: This study was performed at a single centre and only evaluated incisional protection for anaesthetic recovery. Conclusions: Use of a sutured-on stent dressing for anaesthetic recovery did not reduce the rate of SSI compared to a textile adhesive dressing. Further RCT are required to investigate efficacy of other interventions on reduction of SSI following emergency laparotomy

The current study aims to investigate the complication rate of equine appendicular magnetic resonance imaging (MRI) performed under general anesthesia at a tertiary referral center. 1655 horses, donkeys, and mules were included in the study. A complication rate of 1.5% was found in this 9-year study period. The most common complication was post-anesthetic fever with 11 horses becoming pyrexic in the immediate post-anesthetic period. Four of these horses went on to develop clinical pneumonia and one horse had an outbreak of respiratory herpesvirus. The incidence of neuropathy was 0.4% and colic was 0.4%. This study concludes that peri-anesthetic antimicrobial administration would not decrease the risk of complications in horses or donkeys undergoing general anesthesia for MRI of the appendicular skeleton at this tertiary referral center.

Background: Data on equine thoracic pathology hardly exist in other breeds than Thoroughbreds. Objectives: To describe pathological changes of the osseous thoracic vertebral column in Warmblood horses, Shetland ponies and Konik horses, and to compare prevalence and severity. Study design: Descriptive post-mortem study. Methods: Computed tomography examined the thoracic vertebral column of 34 Warmblood horses, 28 Shetland ponies, and 18 Konik horses. Osteoarthritis (OA), periarticular osteolysis (PO), cyst-like lesions (CLL) and fragments of articular processes (APJs), costovertebral (CVJs) and costotransverse (CTJs) joints, soft tissue (ST) mineralisation surrounding these joints, intervertebral disc (IVD) mineralisation, impingement of spinous processes (SPs) and spondylosis were scored. Results: APJ aplasia (98%; 58/ 59) occurred in 14 Shetland ponies. OA predominated in Warmblood horses across all joints (45% vs. 29 and 32%, p<0.001). OA and PO were particularly found in CTJs (p<0.001) across all breeds. Warmblood and Konik horses showed more and severe ST mineralisation than Shetland ponies (2.3%, score 1.5 and 3.2%, score 1.3, respectively, vs. 0.3%, score 0.9, p<0.01). Mid location was most often affected with highest severity score (4.2%, 1.5, p=0.001). Konik horses displayed the highest IVD mineralisation (20%, p<0.001), which notably increased with age (p<0.001) compared to Warmblood horses (4.5%) and Shetland ponies (1.1%). SPs impingement was absent in Shetland ponies, and most prevalent in Warmblood horses (11.2%, p=0.0004) compared to Konik horses (2.2%). CLL, fragments and spondylosis were minimal in all breeds, nearly absent in Shetland ponies. Main limitations: Clinical histories were unavailable. Conclusions: Distinct breed differences exist in prevalence and severity of thoracic vertebral column osseous pathologies. CTJ pathology prevails over APJ in all breeds. Warmblood horses are prone to OA, spondylosis and SPs impingement; Konik horses exhibit significant IVD mineralisation, and Shetland ponies demonstrate high APJ aplasia . PO, CLL, fragments and ST mineralisation are notably low in Shetland ponies.

Background: Fungi are ubiquitous in horses’ environment. Their contribution to the pathophysiology of severe asthma (SA) is acknowledged, while controversies remain for mild-moderate asthma (MA). Objectives: We hypothesized that fungi were a risk factor for asthma. Our objective was to compare different combinations of analytical methods (cytology, culture) and sampling sites (tracheal wash (TW), bronchoalveolar lavage fluid (BALF)) in relation to clinical status (control, MA, SA). Study design: Prospective cross-sectional study. Methods: The study population included asymptomatic racing horses in the field and horses referred to the hospital for respiratory investigations. Fungi were detected by cytology and identified by mycology on TW and pooled BALF. Chi-square tests were used for prevalence comparison between groups and association with clinical investigations. Results: A total of 155 horses (85 MA, 35 SA and 35 controls) were included in the study. The overall proportions of fungal detection in TW ranged from 45.7% to 89.4% among groups. The prevalence of fungal detection in BALF was significantly lower by cytology for SA (5.7%) than MA horses (23.6%) and significantly higher by culture for MA horses (31.8%) than controls (8.6%). Fungal detection by culture in BALF was significantly associated with high tracheal mucus score, high neutrophil proportions in BALF and diagnosis of MA. Main limitations: Mycology was only performed in pooled BALF, and environment was not sampled. Conclusion and clinical importance: Fungi were significantly more prevalent in the airways of MA horses than SA and/or controls. Fungal detection on TW, either by cytology or culture, was uninformative in a clinical context. Fungal detection by culture (but not cytology) in BALF represents a risk factor for MA.

Background: Obesity has been associated with human obstructive sleep apnoea and canine brachycephalic obstructive airway syndrome. To the authors’ knowledge the effect of body condition score (BCS) on structures of the oropharynx , nasopharynx and upper airway of the horse has not been investigated. Objectives: To investigate the effect of BCS on tongue area and height, soft palate angle and basihyoid depth in the horse. Study Design: Retrospective, analytical, cross-sectional. Methods: Computed tomographic (CT) images of the head of 44 horses were assessed. DICOM viewing software was used to measure head length, basihyoid-skin depth, soft palate angle (SPA), midline tongue area and dorsoventral height (DVH) of the tongue in two locations. BCS were assigned at the time of CT examinations. Results: Increased BCS led to an increased mean SPA (mean difference=2.56 ˚ ; P=0.019) and increased median basihyoid depth (mean difference=0.246cm; P=0.006). Following adjustments made for the effect of head length on tongue measures, significant correlation was identified between SPA and tongue area (Spearman’s r=0.544; P=0.007); SPA and DVH of the tongue at the level of the hard palate (Spearman’s r=0.562; P=0.004) and SPA and DVH of the tongue at the lingual process of the basihyoid bone (Spearman’s r=0.690; P<0.001). No significant correlation was identified between variables with sex or age of horses. Conclusions: Increased BCS increases SPA and basihyoid bone depth. Increases in tongue size measurements increase SPA. Results from this study warrant further investigation into the clinical significance of the effects of BCS on the upper airways of the horse.

Background: Selective anthelmintic treatment, advocated due to evolving anthelmintic resistance, has been associated with an increase in Strongylus vulgaris prevalence. Reverting to routine interval anthelmintic treatments is not viable and therefore, identifying other management factors correlated with S. vulgaris infection is vital. Objectives: To investigate possible risk factors associated with the presence of S. vulgaris infection in residing horses on Swedish horse establishments. Study design: Internet-based questionnaire survey. Methods: A questionnaire, created using the internet-based survey platform Netigate, was distributed to owners of equine establishments throughout Sweden via established equine platforms and social media channels. The survey was available for response from May 21 until September 1 2022. Questions were closed ended with branching logic paths. Results: Four factors were significantly associated with S. vulgaris infection, with an increased odds of infection seen in livery yards (OR 1.67, 95% CI 1.18-2.36, p = 0.004) and premises with more than ten residing horses (OR 2.42, 95% CI 1.64-3.56, p < 0.001). A lower odds of infection was seen in establishments using quarantine routines (OR 0.69, 95% CI 0.50-0.96, p = 0.03) and anthelmintic treatment of new horses prior to arrival at the premise (OR 0.37, 95% CI 0.18-0.74, p = 0.005). Main limitation: Due to the presence of S. vulgaris infection in the present study being based on S. vulgaris diagnostics performed at the farm level, any association between faecal diagnostic use and risk of infection could not be investigated. Conclusions: Although the use of diagnostics for S. vulgaris can keep infection rates low, large farms or livery yards with many different horse owners, and those with low use of biosecurity measures as regards to new horses arriving at the premise, are associated with a higher risk of infection.

Rhodococcus equi causes pyogranulomatous pneumonia in foals and immunocompromised people. Despite decades of research efforts, no vaccine is available against this common cause of disease and death in foals. The purpose of this narrative review was to summarize the current understanding of interactions between R. equi and the host innate immune system, to describe features of the immune response that are associated with resistance or susceptibility to R. equi infection, and help guide strategies for developing novel approaches for preventing R. equi infections. Virulence of R. equi in foals has been attributed to the virulence associated protein A which allows intracellular survival in macrophages by preventing acidification of R. equi-containing vacuole. Additionally, foal susceptibility to R. equi infection is associated with immaturity and naivety of innate and adaptive immune systems, while adult horses with fully functional immune system are resistant to pneumonia. Specific interaction between R. equi and innate immune cells can result in bacterial survival or death; learning how to manipulate these responses to control infection is critical to prevent pneumonia in foals. Administration of live vaccines and stimulation of innate immune responses appears to improve foals’ immune response and has the potential to overcome the challenges of foal active vaccination and elicit protection against pneumonia.

Background: The survival of horses diagnosed with critical colic relies on rapid and effective decision-making by owner and veterinary practitioner. Objectives: To explore horse owners’ and veterinary practitioners’ experiences of decision-making for critical cases of equine colic. Methods: A phenomenological approach was taken. Individual, semi-structured telephone interviews were conducted with 14 horse owners and 13 veterinary practitioners (vets) who had experienced a critical decision (referral or euthanasia) for a horse with colic. A purposive, convenience sample of participants was recruited. Sessions explored participant’s experience of colic, including recognition, help-seeking behaviour, and challenges. Thematic analysis was performed on collected data. Results: Four over-arching themes were identified; ‘head’, ‘heart’, ‘practicalities’ and ‘impact’. Owners acknowledged responsibility for their horse’s welfare but had different perspectives to vets on the importance of finance (‘head’). Both vets and owners described how the horse-human relationship (‘heart’) often led to conflict during decision-making. The vet-client relationship was influential on decision-making for both owners and vets; involving other people in decision-making was described both positively and negatively by participants (‘heart’). ‘Practicalities’, such as lack of preparedness, transport issues and adverse weather conditions, were identified by both owners and vets as barriers. Owners described a ‘rollercoaster’ of emotions after a critical decision, with profound impacts on their mental wellbeing, feelings of guilt, and long term changes in behaviour (‘impact’), and a lack of support to manage these feelings. Main Limitations: Small sample size. Conclusions: This study describes stakeholder decision-making during critical cases of equine colic. Factors that commonly influenced decisions included an owner’s previous knowledge and beliefs, social pressures, logistics, and the relationship between owner and vet. The study highlighted long term impacts on the owner, including their management and decisions for subsequent horses. These factors should be considered and included in shared decision-making for critical cases of colic.

Background: Few studies have investigated the adequate contrast enhancement (CE) evaluation depending on concentration, volume, and rate of contrast media (CM) and the scan parameters in equine contrast enhanced computed tomography (CECT). Objectives: We investigated CE of the deep digital flexor tendon (DDFT) and arteries depending on voltage, concentration, volume, and rate of CM during intra-arterial CECT of equine distal forelimbs. Study design: This is a prospective study. Methods: Six horses underwent fifty-four CT scans. First, the CE of DDFT and arteries was evaluated depending on the voltage (80 or 120 kV) and CM concentration (150, 120, or 90 mg I/mL in 50 mL of CM). Second, CE of DDFT and vessels was evaluated depending on the CM volume (50, 100, or 150 mL) and administration rate (2, 4, or 6 mL/s) with a fixed iodine delivery rate (IDR) (300 or 180 mg I/s). Results: CE of DDFT significantly increased at 80 kV of voltage and 150 mg I/mL of CM concentration (Median: 29.65; IQR: 1.74; P < 0.05). CE of the DDFT positively correlated with CM concentration (P = 0.0004; r = 0.75). At 180 mg I/s of IDR, an increase in rate and volume (6 mL/s and 150 mL) led to low contrast attenuation in the medial and lateral palmar arteries (median and IQR: 985.93 and 71.8 Hounsfield units [HU] and 988.73 and 41.16 HU, respectively); the CE was sufficient to distinguish the artery from the adjacent structures. Main limitations: The number of animals was small for parametric statistical analysis. Conclusions: Our results suggest that a low CM concentration could yield sufficient CE of the DDFT and arteries with adjusted CT scanning parameters or volume and injection rate of CM.

Background: Limited literature exists regarding equine Immune Mediated Keratitis (IMMK) in Europe. North America-based publications describe minimal blepharospasm, rare corneal ulceration and no uveitis; clinical impression suggests that these signs are common in Europe. Objectives. Assess the prevalence of blepharospasm, corneal ulceration and uveitis and their impact on outcome in horses diagnosed with IMMK in European countries. Study design: Retrospective case series of 95 horses with IMMK in the UK and Finland. Methods. Clinical records of horses with IMMK were retrospectively evaluated. The UK and Finland populations were comparable; therefore, descriptive statistics were performed on combined data on subtypes of IMMK and clinical features. Odds ratios (OR) and confidence intervals (CI) were calculated for impact of blepharospasm, ulceration or presence of uveitis on the outcome of enucleation and treatment duration. Results. IMMK subtype was classified as 10/95 (10.5%) epithelial, 50/95 (52.6%) anterior stromal, 15/95 (15.8%) mid-stromal, 4/95 (4.2%) endothelial cases and 16/19 (16.8%) unrecorded. Blepharospasm was documented in 35/95 (36.8%), corneal ulceration in 28/95 (29.5%), and signs of uveitis in 24/95 (25.4%) of horses. Increased odds of enucleation were associated with the presence of blepharospasm (OR 5.9, 95% CI 1.7-20.8), corneal ulceration (OR 3.3, 95% CI 1.0-10.5) and signs of uveitis (OR 8.6, 95% CI 2.5-29.6). The presence of blepharospasm, corneal ulceration or uveitis did not significantly alter the odds of ongoing medication. Main limitations: Data were collected over a wide timeframe and the diagnosis was mainly made without histopathology. A broad definition of uveitis was used and there was a bias towards complicated cases being retained for follow up. Conclusions. The clinical features of IMMK were similar between two geographically distinct European countries but different to findings described in the USA. Blepharospasm, corneal ulceration and signs of uveitis can occur with IMMK and increase the odds of enucleation.