Positron emission tomography assessment of metacarpal/metatarsal condylar fractures post surgical repair: Prospective study in 14 racehorses.

OBJECTIVES: To assess 18F-sodium fluoride (18F-NaF) positron emission tomography (PET) findings associated with metacarpal/metatarsal condylar fractures at the time of fracture repair and through healing. STUDY DESIGN: Prospective descriptive study. ANIMALS: Fourteen Thoroughbred racehorses. METHODS: 18F-NaF PET was performed within 4 days of surgical metacarpal/metatarsal condylar fracture repair, on both the injured and contralateral limb. Follow-up PET scans were offered at 3- and 5-months post fracture repair. Areas of abnormal uptake were assessed using a previously validated grading system. RESULTS: Eight fractures were located in the parasagittal groove (PSG) (six lateral and two medial) and six fractures were located abaxial to the PSG (non-PSG) through the palmar/plantar condyle (all lateral). All horses in the latter group had uptake in the lateral palmar condyle of the contralateral limb suggestive of stress remodeling. Three horses with PSG fractures had uptake in a similar location in the contralateral limb. Horses with lateral condylar fracture only presented minimal or mild uptake in the medial condyle, which is considered atypical in the front limbs for horses in full training. Four horses developed periarticular uptake in the postoperative period suggestive of degenerative joint disease, three of these horses had persistent uptake at the fracture site. These four horses did not return to racing successfully. CONCLUSION: The findings of this study provide evidence of pre-existing lesions and specific uptake patterns in racehorses suffering from metacarpal/metatarsal condylar fractures. CLINICAL SIGNIFICANCE: PET has a possible role in the prevention, diagnosis, and postoperative monitoring of metacarpal/metatarsal condylar fractures in racehorses.

Assessment of BPV-1 Mediated Matrix Metalloproteinase Genes Deregulation in the In Vivo and In Vitro Models Designed to Explore Molecular Nature of Equine Sarcoids.

Matrix metalloproteinases (MMPs) represent a family of enzymes capable of biocatalytically breaking down the structural and functional proteins responsible for extracellular matrix (ECM) integrity. This capability is widely used in physiological processes; however, imbalanced MMP activity can trigger the onset and progression of various pathological changes, including the neoplasmic transformation of different cell types. We sought to uncover molecular mechanisms underlying alterations in transcriptional profiles of genes coding for MMPs, which were comprehensively identified in equine adult dermal tissue bioptates, sarcoid-derived explants, and ex vivo expanded adult cutaneous fibroblast cell (ACFC) lines subjected to inducible oncogenic transformation into sarcoid-like cells. The results strongly support the hypothesis that the transcriptional activity of MMP genes correlates with molecular modifications arising in equine dermal cells during their conversion into sarcoid cells. The alterations in MMP transcription signatures occurs in both sarcoid tissues and experimentally transformed equine ACFC lines expressing BPV1-E4^E1 transgene, which were characterized by gene up- and down-regulation patterns.

Assessment of agreement using the equine glandular gastric disease grading system in 84 cases.

INTRODUCTION: Equine glandular gastric disease (EGGD) is a common condition causing signs of gastric pain although lesions are highly variable in their appearance. The only definitive method to diagnose EGGD ante-mortem is gastroscopy. The current recommended method for describing these lesions is the European College of Equine Internal Medicine (ECEIM) guidelines; however, repeatability between users is variable. This study aimed to validate the reliability of lesion descriptions using ECEIM consensus guidelines, using four blinded equine internal medicine diplomates. METHODS: Ninety-two horses with EGGD with pre- and post-treatment gastroscopy images were identified using the electronic record at a UK equine hospital between 2012 and 2019. Eight horses were excluded due to non-diagnostic images. Four blinded observers used the recommended grading system to describe images and outcomes. Intraclass correlation coefficients and Krippendorff's alpha were used to determine reliability and agreement, respectively. RESULTS: Intraclass correlation coefficient for severity was 0.782 (95% confidence interval [CI] 0.722-0.832), for distribution was 0.671 (95% CI 0.540-0.763), for the descriptor raised was 0.635 (95% CI 0.479-0.741), fibrinosuppurative was 0.745 (95% CI 0.651-0.812), haemorrhagic was 0.648 (95% CI 0.513-0.744), hyperaemic was 0.389 (95% CI 0.232-0.522) and for outcome was 0.677 (95% CI 0.559-0.770). Krippendorff's alpha for severity was 0.466 (95% CI 0.466-0.418), for distribution was 0.304 (95% CI 0.234-0.374), for the descriptor raised was 0.268 (95% CI 0.207-0.329), fibrinosuppurative was 0.406 (95% CI 0.347-0.463), haemorrhagic was 0.287 (95% CI 0.229-0.344), hyperaemic was 0.112 (95% CI 0.034-0.188) and for outcome was 0.315 (95% CI 0.218-0.408). There was moderate reliability determined between observers using intra-class correlation coefficients and unacceptable agreement determined between observers using Krippendorff's alpha. DISCUSSION: These results suggest that the current grading system is not comparable between observers, indicating the need to review the grading system or define more robust criteria.

Practical Tips on Sample Handling for Hematology, Chemistry, and Cytology Testing for Equine Patients:: Getting More Bang for your Buck.

Clinical pathology results are only as good as the quality of samples and accompanying information submitted to the diagnostic laboratory. The frustration of nondiagnostic or equivocal test results can often be avoided by taking the time to follow sample handling and submission guidelines. This article discusses preanalytical errors that commonly affect the accuracy of hematology, chemistry, and cytology testing, and offers practical tips for preventing these errors and maximizing diagnostic yield.

Assessment of sand accumulation in the gastrointestinal tract and its excretion with stool in silesian foals.

The aim of this study was to assess sand accumulation in the gastrointestinal tract and fecal sand excretion in Silesian foals using three diagnostic methods and taking into account the sex and age of the animals. Another aim of the study was to compare the three diagnostic methods. The study was carried out on 21 clinically healthy Silesian foals (10 females and 11 males) from 9-28 weeks old grazed on permanent pasture. The sand intake was assessed using a sedimentation test, abdominal ultrasonography and a quantitative evaluation of sand per 100 g of stool. In the sedimentation test, the sand was palpable in the stool of 57.1% of the horses, and clearly visible in 42.9% of the animals. The ultrasound examination revealed the presence of sand in the gastrointestinal tract in 66.7% of the horses. It was limited to a single location in 60% of the horses, while it was present in several regions in 40% of the horses. The mean amount of sand was 0.14 ± 0.33 g per 100 g of stool. It did not exceed 0.1g in 71.4% foals, while it ranged from 0.1-0.5 g in 23.8% foals. In 4.8% of the animals, it amounted to 1.6 g per 100 g of stool. There was no correlation between age and gender and the results. There was a positive correlation between the ultrasound examination and the sedimentation test. Sand may be accumulated in the gastrointestinal tract of foals without any clinical signs. The amount of sand excreted in the stool is not an indicator of the amount of sand accumulated in the gastrointestinal tract. An abdominal ultrasound examination should be combined with a sedimentation test for more specific results.

Peripheral caries and disease of the periodontium in Western Australian horses: An epidemiological, anatomical and histopathological assessment.

BACKGROUND: Peripheral caries may cause significant oral pain and pathology and is very prevalent within the Western Australia horse population. Associations with periodontal disease have been indicated; however, further work is needed to assess the anatomical and histological aspects of the conditions, to better understand the pathophysiology. OBJECTIVES: To assess the anatomical and histopathological changes associated with equine cheek teeth peripheral caries and disease of the periodontium to better understand the pathogenesis and any association between the conditions. STUDY DESIGN: Cross-sectional epidemiological and histological study. METHODS: A survey of 500 Western Australia horses was performed to assess the prevalence of peripheral caries and associations with other dental pathologies within the Western Australia horse population. Histopathological assessment was also performed on four extracted cheek teeth affected by peripheral caries and on three interdental areas from an abattoir specimen affected by peripheral caries and interdental feed accumulation. RESULTS: There was a significant association between peripheral caries and cheek teeth interdental feed accumulation and gingival recession. This association was significantly stronger in the mandibular cheek teeth than the maxillary cheek teeth and also in horses with moderate or severe peripheral caries compared to horses with mild peripheral caries. Histopathological examination found caries lesions consistent with those found in humans above the gingival margin. Sub-gingivally, however, the cementum and periodontal structures were normal. In the samples with concurrent peripheral caries and deep feed-pocketing, there was significant gingival recession; however, only mild or no histopathological changes occurred in the gingiva. MAIN LIMITATIONS: Small sample size for histopathological assessment. CONCLUSION: Horses with peripheral caries, and in particular, horses with mandibular cheek teeth with peripheral caries are significantly more likely to also be affected by disease of the periodontium than horses without peripheral caries.

Assessment of tissue-specific cortisol activity with regard to degeneration of the suspensory ligaments in horses with pituitary pars intermedia dysfunction.

OBJECTIVE To identify signs of tissue-specific cortisol activity in samples of suspensory ligament (SL) and neck skin tissue from horses with and without pituitary pars intermedia dysfunction (PPID). SAMPLE Suspensory ligament and neck skin tissue samples obtained from 26 euthanized horses with and without PPID. PROCEDURES Tissue samples were collected from 12 horses with and 14 horses without PPID (controls). Two control horses had received treatment with dexamethasone; data from those horses were not used in statistical analyses. The other 12 control horses were classified as old horses (≥ 14 years old) and young horses (≤ 9 years old). Standard histologic staining, staining for proteoglycan accumulation, and immunostaining of SL and neck skin tissue sections for glucocorticoid receptors, insulin, 11ß hydroxysteroid dehydrogenase type 1, and 11ß hydroxysteroid dehydrogenase type 2 were performed. Findings for horses with PPID were compared with findings for young and old horses without PPID. RESULTS Compared with findings for old and young control horses, there were significantly more cells stained for glucocorticoid receptors in SL samples and for 11 ß hydroxysteroid dehydrogenase type 1 in SL and skin tissue samples from horses with PPID. Insulin could not be detected in any of the SL or skin tissue samples. Horses with PPID had evidence of SL degeneration with significantly increased proteoglycan accumulation. Neck skin tissue was found to be significantly thinner in PPID-affected horses than in young control horses. CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that tissue-specific dysregulation of cortisol metabolism may contribute to the SL degeneration associated with PPID in horses.

Assessment of a novel equine tarsocrural experimental joint disease model using recombinant interleukin-1ß and arthroscopic articular sampling of the medial malleolus of the tibia on the standing sedated horse.

Joint disease and osteoarthritis are common problems in the horse and numerous experimental studies have been developed to determine the safety and efficacy of new therapies. Synovitis, a critical component of joint disease, has been experimentally induced using recombinant interleukin-1 beta (reIL-1ß) to investigate new joint therapies in a controlled environment, although the use of reIL-1ß has not been reported in the equine tarsocrural joint. A common consequence of performing controlled experiments is that articular tissue collection typically requires general anesthesia or euthanasia. This report describes a minimally invasive surgical biopsy technique to harvest joint tissues from the tarsocrural joint in standing horses. The aims of the study were to assess subjective and objective pain parameters following reIL-1ß induced synovitis in the tarsocrural joint and to describe the surgical technique including the location and quantity of tissues obtained with this method. Experimental synovitis was induced using reIL-1ß in one equine tarsocrural joint of each horse using a randomised controlled design. The minimally invasive surgical technique provided sufficient amounts of articular cartilage from the medial malleolus of the tibia and synovium to perform viability, biochemical and histological assessments without necessitating general anesthesia. The minimally invasive technique also allowed for lameness assessment that could have been influenced by more invasive methods of tissue collection. No incisional or lameness complications were detected after use. The synovitis model and surgical technique provided ample tissue for laboratory evaluation and avoided general anesthesia or sacrifice of the horse.

Retrospective evaluation of 155 adult equids and 21 foals with tetanus from Western, Northern, and Central Europe (2000-2014). Part 2: Prognostic assessment.

OBJECTIVE: To identify prognostic variables for adult equids and foals with tetanus. DESIGN: Multicenter retrospective study (2000-2014). SETTING: Twenty Western, Northern, and Central European university teaching hospitals and private referral centers. ANIMALS: One hundred fifty-five adult equids and 21 foals with tetanus. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Variables from history and clinical examination were statistically compared between survivors and nonsurvivors (adults: 49 survivors, 85 nonsurvivors; foals: 7 survivors, 10 nonsurvivors). Cases euthanized for financial reasons were excluded. Mortality rates in adults and foals were 68.4% and 66.7%, respectively. Variables associated with survival in adults included: standing, normal intestinal sounds and defecation, voluntarily drinking, eating soft or normal food, lower heart and respiratory rates, high base excess on admission, longer diagnosis time, treatment and hospitalization delay, and mild severity grade. Variables associated with death included: anorexia, dysphagia, dyspnea, low blood potassium concentration on admission, moderate and severe disease grading, development of dysphagia, dyspnea, recumbency and seizures during hospitalization, treatment with glycerol guaiacolate, intravenous fluids, and intravenous glucose solutions. Variables associated with survival in foals included standing on admission, voluntarily eating soft food and drinking, older age, and longer hospitalization delay. Outcome was not different between different tetanus antitoxin (TAT) dosages, although there was a trend of increasing survival rate with increasing TAT dosages. Cases with appropriate vaccination prior to development of tetanus were rare, but had improved outcome and shorter hospitalization. CONCLUSIONS: Prognosis for equine tetanus is poor with similar outcome and prognostic factors in foals and adults. The prognostic assessment of cases with tetanus provides clinicians with new evidence-based information related to patient management. Several prognostic indicators relate to the ability to eat or drink, and more severe clinical signs relate to poor outcome. Increasing intravenous dosages of TAT has no significant effect on outcome, but the positive trend identified may support a recommendation for high intravenous TAT dosages. Further evaluation is warranted.

Sales performance and athletic outcome in young Thoroughbreds with pericarditis.

BACKGROUND: Pericarditis is a sporadic, but important cause of critical illness in horses of all ages. There is limited information on whether Thoroughbred horses that survive pericarditis are able to reach athletic potential. OBJECTIVES: To determine how pericarditis affected horses that had the disease as young animals with regard to selling price in public sales and the ability to race successfully. STUDY DESIGN: Retrospective case series. METHODS: Medical records were searched to identify pericarditis cases. Signalment and month of diagnosis were noted and Thoroughbreds with ultrasonographically confirmed pericarditis that presented from 2 months to 3 years old were identified. For this subgroup data on sales and racing performed were obtained from publicly available databases to determine long-term survival and post-treatment outcomes from these horses and their unaffected half-siblings. RESULTS: Horses that survived pericarditis as young animals may recover growth and maturation rates quickly enough to reach expected sales prices at public sales for horses of racing age and recovered horses can have successful racing careers. MAIN LIMITATIONS: The number of horses in this case series was not sufficient to enable statistical comparisons between affected horses and unaffected half-siblings, but description of sales prices and race earnings nevertheless yields information about the chances for affected young horses to achieve their intended purposes. CONCLUSIONS: Young Thoroughbreds with pericarditis warrant treatment and can sell and have successful racing careers.

Assessment of horse owners' ability to recognise equine laminitis: A cross-sectional study of 93 veterinary diagnosed cases in Great Britain.

BACKGROUND: Use of owner-reported data could further epidemiological knowledge of equine laminitis. However, owner recognition of laminitis has not previously been assessed. OBJECTIVES: The primary objective was to establish whether cases of owner-suspected laminitis would be confirmed as laminitis by the attending veterinary surgeon. Secondary objectives were to compare owner- and veterinary-reported information from veterinary-confirmed cases of equine laminitis. STUDY DESIGN: Cross-sectional study. METHODS: Twenty-five British veterinary practices were invited to submit laminitis reporting forms (LRFs) for active laminitis cases attended between January 2014 and October 2015; detailing 27 clinical signs, 5 underlying conditions and 7 risk factors associated with laminitis. Owners were invited to independently complete a modified LRF if reason for the veterinary visit was suspicion of laminitis. Differences between paired veterinary and owner LRFs, and between cases where owners did and did not recognise laminitis, were assessed using McNemar's and Fisher's Exact tests, respectively. RESULTS: Veterinary LRFs were received for 93 veterinary-diagnosed laminitis cases. All 51 owner-suspected cases were confirmed by veterinary diagnosis, with the remaining 42 (45.2%) not recognised as laminitis by owners. Undefined lameness, foot abscesses, colic and stiffness were common reasons for owner-requested veterinary visits in owner-unrecognised cases. 'Divergent growth rings' (prevalence difference: +27.3%, P = 0.01) and 'breed type' (prevalence difference: +21.2%, P = 0.04) were more commonly reported by veterinary surgeons in owner-recognised compared to owner-unrecognised cases. 'Difficulty turning', 'shifting weight' and risk factor 'body condition' were more frequently reported by veterinary surgeons whilst 'increased hoof temperature' was reported more frequently by owners. MAIN LIMITATIONS: The limited clinical data restricted statistical inferences regarding the secondary objectives. CONCLUSIONS: All owner-suspected laminitis cases were confirmed upon veterinary examination, showing validity for the inclusion of owner-reported cases in future epidemiological studies. However, failure of laminitis recognition by owners highlights further need for evidence-based education to ensure early disease detection.

Early detection of West Nile virus in France: quantitative assessment of syndromic surveillance system using nervous signs in horses.

West Nile virus (WNV) is a growing public health concern in Europe and there is a need to develop more efficient early detection systems. Nervous signs in horses are considered to be an early indicator of WNV and, using them in a syndromic surveillance system, might be relevant. In our study, we assessed whether or not data collected by the passive French surveillance system for the surveillance of equine diseases can be used routinely for the detection of WNV. We tested several pre-processing methods and detection algorithms based on regression. We evaluated system performances using simulated and authentic data and compared them to those of the surveillance system currently in place. Our results show that the current detection algorithm provided similar performances to those tested using simulated and real data. However, regression models can be easily and better adapted to surveillance objectives. The detection performances obtained were compatible with the early detection of WNV outbreaks in France (i.e. sensitivity 98%, specificity >94%, timeliness 2·5 weeks and around four false alarms per year) but further work is needed to determine the most suitable alarm threshold for WNV surveillance in France using cost-efficiency analysis.

Tracheobronchoscopic Assessment of Exercise-Induced Pulmonary Hemorrhage and Airway Inflammation in Barrel Racing Horses.

BACKGROUND: Poor performance is often suspected to be associated with EIPH in barrel racing horses; however, there are no published reports of EIPH for this discipline. The prevalence of EIPH in barrel racing horses is also unknown. OBJECTIVES: This study was performed to determine the prevalence of EIPH and signs of airway inflammation in barrel racing horses under normal racing conditions in Alberta. ANIMALS: About 170 barrel racing horses. METHODS: Observational cross-sectional study. Tracheobronchoscopic examinations were performed at least 30 minutes postrace. Video recordings were scored off-site independently by two observers for EIPH and tracheal mucus accumulation (TMA). Horses with an EIPH score ≥2 were not assessed for TMA. Interobserver agreement was calculated by weighted κ statistics. Run times, environmental variables, and clinical information were also recorded for analysis. RESULTS: 77/170 (45.3%) of horses examined showed evidence of EIPH (grade ≥ 1). Interobserver agreement was 0.94. 140/141 (99.3%) of horses assessed for TMA showed evidence of tracheal mucus accumulation (grade ≥ 1) with 104/141 (73.8%) having a TMA score ≥ 2. Interobserver agreement was 0.73. A weak positive association was found between EIPH scores and average run speed, the presence of cough at rest reported by the riders, increased recovery time, exercise intolerance, and outdoor pattern. CONCLUSIONS AND CLINICAL IMPORTANCE: The high prevalence of EIPH observed in the sampled population indicates that barrel racing induces substantial stress on the lungs. The presence of EIPH did not impact negatively on performance. Factors such as environmental dust and frequent traveling might have contributed to the high prevalence of TMA observed.

Comparative study of equine mesenchymal stem cells from healthy and injured synovial tissues: an in vitro assessment.

BACKGROUND: Bone marrow and adipose tissues are known sources of mesenchymal stem cells (MSCs) in horses; however, synovial tissues might be a promising alternative. The aim of this study was to evaluate phenotypic characteristics and differentiation potential of equine MSCs from synovial fluid (SF) and synovial membrane (SM) of healthy joints (SF-H and SM-H), joints with osteoarthritis (SF-OA and SM-OA) and joints with osteochondritis dissecans (SF-OCD and SM-OCD) to determine the most suitable synovial source for an allogeneic therapy cell bank. METHODS: Expression of the markers CD90, CD105, CD44, and CD34 in SF-H, SM-H, SF-OA, SM-OA, SF-OCD and SM-OCD was verified by flow cytometry, and expression of cytokeratin, vimentin, PGP 9.5, PCNA, lysozyme, nanog, and Oct4 was verified by immunocytochemistry. MSCs were cultured and evaluated for their chondrogenic, osteogenic and adipogenic differentiation potential. Final quantification of extracellular matrix and mineralized matrix was determined using AxioVision software. A tumorigenicity test was conducted in Balb-C(nu/nu) mice to verify the safety of the MSCs from these sources. RESULTS: Cultured cells from SF and SM exhibited fibroblastoid morphology and the ability to adhere to plastic. The time elapsed between primary culture and the third passage was approximately 73 days for SF-H, 89 days for SF-OCD, 60 days for SF-OA, 68 days for SM-H, 57 days for SM-OCD and 54 days for SM-OA. The doubling time for SF-OCD was higher than that for other cells at the first passage (P < 0.05). MSCs from synovial tissues showed positive expression of the markers CD90, CD44, lysozyme, PGP 9.5, PCNA and vimentin and were able to differentiate into chondrogenic (21 days) and osteogenic (21 days) lineages, and, although poorly, into adipogenic lineages (14 days). The areas staining positive for extracellular matrix in the SF-H and SM-H groups were larger than those in the SF-OA and SM-OA groups (P < 0.05). The positive mineralized matrix area in the SF-H group was larger than those in all the other groups (P < 0.05). The studied cells exhibited no tumorigenic effects. CONCLUSIONS: SF and SM are viable sources of equine MSCs. All sources studied provide suitable MSCs for an allogeneic therapy cell bank; nevertheless, MSCs from healthy joints may be preferable for cell banking purposes because they exhibit better chondrogenic differentiation capacity.

Prognosis and impact of equine recurrent uveitis.

REASONS FOR PERFORMING STUDY: Equine recurrent uveitis (ERU) is a leading cause of vision loss in horses. OBJECTIVES: To assess the prognosis and impact of ERU on affected horses and their owners by evaluating the signalment, treatment and outcome (including the loss of use, vision assessment and economic loss). STUDY DESIGN: Retrospective impact study. METHODS: Medical records of horses presenting to the North Carolina State University Veterinary Health Complex (NCSU-VHC) with ERU between 1999 and 2014 were reviewed. Signalment, clinical signs, ophthalmic examination findings, treatments and outcomes were evaluated. Owner questionnaires were completed regarding vision, job/role, monetary value, diagnostic and treatment costs, concurrent illness and outcomes. RESULTS: Records of 224 horses (338 eyes) with ERU were reviewed. There was an overrepresentation of Appaloosas (54; 24.1%), Hanoverians (11; 4.9%) and other Warmbloods (13; 5.8%). Ninety-six eyes (28.4%) were diagnosed as blind and 38 eyes (11.2%) with glaucoma on initial evaluation. Leptospirosis titres of serum and/or aqueous humour were obtained in 88 horses and were positive in 40 horses (45.5%), with L. pomona being the most frequently isolated serovar. Globe loss at the NCSU-VHC occurred in 41 ERU eyes (12.1% of total). Owner questionnaires were evaluated in 194 horses (86.6%) and 91 horses (46.9%) were reported blind in the affected eye(s). Fifty-seven horses (29.4%) did not return to their previous role, while 61 (31.4%) performed at a reduced level. Equine recurrent uveitis decreased the monetary value of 164 horses. Twenty-nine horses (14.9%) were euthanised and 37 (19.1%) underwent change in ownership as a direct result of ERU. CONCLUSIONS: The impact of ERU is attributed to the high frequency of blindness, globe loss and loss of function. Euthanasia and change of ownership are common sequelae to the progressive nature of ERU. These factors, along with financial costs of the disease, have a significant impact on affected horses and their owners.

Cytological evaluation of tracheal aspirate and broncho-alveolar lavage fluid in comparison to endoscopic assessment of lower airways in horses with recurrent airways obstruction or inflammatory airway disease.

The aim of the present study was to compare the grade of discharge accumulation in the tracheal lumen, area of tracheal bifurcation, main bronchi and the tracheal septum thickness with the cytology of the tracheal aspirate (TA) and broncho-alveolar lavage fluid (BALF) in horses with recurrent airways obstruction and inflammatory airway disease from those horses. This study was conducted on 96 horses with RAO, 139 horses with IAD and 10 control horses. In all the horses, both clinical and endoscopic examinations were performed. During endoscopy, a score of mucus accumulation was estimated in 3/4 lower of the trachea and in the tracheal bifurcation. In addition, thickening of the tracheal septum was also assessed; tracheal aspirates and broncho-alveolar lavage were performed. An estimate of cell percentage was done in TA and BALF samples. In horses suffering from RAO and IAD, there was a positive correlation between the percentage of neutrophils and the accumulation of discharge, and in the IAD group, there was a negative correlation between the percentage of eosinophils and the accumulation of discharge. There was no correlation between tracheal septum thickening and the percentage of neutrophils and/or eosinophils.

Histopathological assessment of intrinsic laryngeal musculature in horses with dynamic laryngeal collapse.

REASONS FOR PERFORMING STUDY: The pathogenesis of bilateral dynamic laryngeal collapse associated with poll flexion (DLC) of horses is unknown but might be associated with intrinsic laryngeal muscle weakness. OBJECTIVES: To investigate histopathological characteristics of the cricoarytenoideus dorsalis, the cricothyroid (CT) and the cricoarytenoideus lateralis muscles in DLC-affected horses and compare these with unaffected controls. Our hypotheses were that evidence of neurogenic atrophy of the CT or cricoarytenoideus dorsalis muscles would be found in DLC-affected horses and that observed changes would be symmetrically (left/right) distributed, or that muscle fibre diameter would be significantly reduced in DLC-affected horses compared to unaffected controls, reflecting an underlying paresis. STUDY DESIGN: Case-control study. METHODS: Five DLC horses and 8 controls were included. Muscle samples were harvested immediately following euthanasia. Fibre type proportions and size were evaluated by multiple immunofluorescence labelling of cryosections, and compared between sides (left/right) and groups (DLC-affected cases/ unaffected controls). Subjective and objective assessments of fibre type grouping were compared between sides and groups. RESULTS: Fibre type proportions, fibre size and the subjective assessment of fibre type grouping did not reveal any statistically significant differences between the groups. Objective assessment of fibre type grouping revealed significantly more large clusters of T1 fibres within the left cricoarytenoideus lateralis muscle of DLC-affected cases versus controls, and within the right CT muscle of control horses compared to the DLC-cases. CONCLUSIONS: The absence of bilateral symmetric fibre type grouping, fibre type loss and fibre atrophy in the DLC-affected cases do not support a neuromuscular component within the pathogenesis of DLC. The objective assessment of fibre type grouping revealed some statistical differences between the DLC-affected cases and the unaffected controls; however, these findings were inconsistent with regard to DLC. An alternative aetiology of DLC seems likely.

Usefulness of the assessment of discharge accumulation in the lower airways and tracheal septum thickening in the differential diagnosis of recurrent airway obstruction (RAO) and inflammatory airway disease (IAD) in the horse.

The aim of the present study was to use endoscopic evaluation to compare the grade of accumulation of discharge in the lower airways of horses with recurrent airway obstruction (RAO) and inflammatory airway disease (IAD), and to estimate the usefulness of endoscopic evaluation in differential diagnosis of these diseases. Endoscopic evaluation consists of: the amount of discharge in the lower part of the trachea and tracheal bifurcation, and the assessment of tracheal septum thickness. This study was performed on 248 horses, 10 were healthy, 97 were diagnosed as RAO, and 141 were diagnosed as IAD. In all animals both a clinical and endoscopic examination were performed. During endoscopy, a score of mucus accumulation was estimated in 3/4 lower of the trachea and in the tracheal bifurcation. In addition to this, thickening of the tracheal septum was also assessed. According to the results of this study, it was estimated that the accumulation of mucus in the lower airways was much more advanced in RAO horses compared to horses with IAD. In horses with RAO there was a marked thickening of the tracheal septum compared to IAD horses. The results indicate the efficacy of scoring the amount of mucus in the tracheal lumen and tracheal bifurcation, as well as the efficacy of the assessment of tracheal septum thickness in the diagnosis of these diseases.

Dark-field microscopy in the assessment of large colon microperfusion and mucosal injury in naturally occurring surgical disease of the equine large colon.

REASON FOR PERFORMING STUDY: Intraoperative assessment of colonic viability can be challenging and largely subjective. Objective methods are often impractical. Viability is related to re-establishment of colonic perfusion; particularly microvascular perfusion. This study evaluated the utility of dark-field microscopy (DFM) of the colonic serosa as an objective method of assessing microperfusion. OBJECTIVES: To measure microvascular perfusion indices (MPI) of the pelvic flexure serosa in horses with surgical colonic lesions and correlate these with macroperfusion indices (MaPI) and histomorphometry. STUDY DESIGN: Prospective, clinical, case-control study. METHODS: Control horses and horses with colonic volvulus (LCV), displacement, and/or simple obstruction undergoing surgery had DFM video loops performed on the pelvic flexure. Total vessel density, perfused vessel density, proportion of perfusion vessels and microvascular flow index were calculated from video analysis. Macroperfusion indices (arterial blood pressure and heart rate) were recorded. Histomorphometry was used to determine a mucosal injury score. Differences between lesions for MPI, MaPI and histomorphometry were compared using ANOVA or Kruskal-Wallis statistic. Spearman correlations between MPI with MaPI were performed. Linear regression was used to assess the relationship between MPI and histomorphometry. P<0.05 was significant. RESULTS: Horses with LCV had lower perfused vessel density, proportion of microvascular perfusion vessels and flow index than horses with nonstrangulating obstructions and control horses. Macroperfusion indices were not correlated with MPI but MPI were correlated with histomorphometry. CONCLUSIONS: Dark-field microscopy is achievable in the operating room and can quantify MPI from the colonic serosa in different colonic lesions. Macroperfusion indices were not related with colonic MPI. Microvascular perfusion indices can predict the severity of histopathological change at the pelvic flexure. Derangements of MPI may be more useful indicators of colonic pathology and viability and offer a more objective assessment of intestinal injury than subjective methods. Further study is needed to determine the utility of DFM in predicting survival in horses with LCV.