No abstract

Exercise-induced pulmonary hemorrhage (EIPH) is common in horses following intense exertion, occurring in up to 75% of racing Thoroughbreds and Standardbreds. In spite of this, the pathogenesis of EIPH is poorly understood. In 7 racing Thoroughbred horses with EIPH, 6 sections were collected from the left and right lung, representing the cranial, middle, and caudal region of the dorsal and ventral lung (84 sites total). Grossly, both right and left lungs had numerous dark brown to blue-black foci along the caudodorsal visceral pleura. Tissue sections were stained with hematoxylin-eosin, Masson's trichrome, and Prussian blue. Verhoeff Van Gieson and immunohistochemistry for alpha-smooth muscle actin were used to assess the pulmonary vasculature. Histologic scores (HS = 0-3) were assigned to each region/slide for the presence and severity of 5 findings: interstitial fibrosis, hemosiderin accumulation, pleural/interlobular septal thickness, arterial and venous wall thickness, and evidence of angiogenesis (maximum cumulative HS = 15). Thirty-nine of the 84 (46%) sections were histologically normal (HS = 0); 33/84 (39%) were mildly to moderately affected, with small amounts of hemosiderin and fibrosis (HS = 1-9) while 12/84 (14%), primarily from the dorsocaudal lung, had severe vascular remodeling, fibrosis, and hemosiderin accumulation (HS = 10-15). In the latter, veno-occlusive remodeling of the intralobular veins colocalized with hemosiderosis, fibrosis, hypertrophy of vessels within the pleura, and interlobular septa and bronchial neovascularization. We propose that regional veno-occlusive remodeling, especially within the caudodorsal lung fields, contributes to the pathogenesis of EIPH, with the venous remodeling leading to regional vascular congestion and hemorrhage, hemosiderin accumulation, fibrosis, and bronchial angiogenesis.

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Septic arthritis is an uncommon complication of IAM in horses, yet the risk is substantially higher than that reported in humans. The risk was higher for some veterinarians; identifying the reason for this was beyond the scope of this study, yet we presume they may have paid less attention to strict aseptic technique. A larger study may be needed to clarify whether the risk is greater with certain types of corticosteroids and to identify additional risk factors.

Michigan (FJD,NER)S U M M A R Y We used immunohistochemistry to examine myosin heavy-chain (MyHC)-based fiber-type profiles of the right and left cricoarytenoideus dorsalis (CAD) and arytenoideus transversus (TrA) muscles of six horses without laryngoscopic evidence of recurrent laryngeal neuropathy (RLN). Results showed that CAD and TrA muscles have the same slow, 2a, and 2x fibers as equine limb muscles, but not the faster contracting fibers expressing extraocular and 2B MyHCs found in laryngeal muscles of small mammals. Muscles from three horses showed fiber-type grouping bilaterally in the TrA muscles, but only in the left CAD. Fiber-type grouping suggests that denervation and reinnervation of fibers had occurred, and that these horses had subclinical RLN. There was a virtual elimination of 2x fibers in these muscles, accompanied by a significant increase in the percentage of 2a and slow fibers, and hypertrophy of these fiber types. The results suggest that multiple pathophysiological mechanisms are at work in early RLN, including selective denervation and reinnervation of 2x muscle fibers, corruption of neural impulse traffic that regulates 2x and slow muscle fiber types, and compensatory hypertrophy of remaining fibers. We conclude that horses afflicted with mild RLN are able to remain subclinical by compensatory hypertrophy of surviving muscle fibers. (J Histochem Cytochem 57:787-800, 2009)

BackgroundCommunication and teamwork failures have frequently been identified as the root cause of adverse events and complications in surgery. Few studies have examined contextual factors that influence teams’ non-technical skills (NTS) in surgery. The purpose of this prospective study was to identify and describe correlates of NTS.MethodsWe assessed NTS of teams and professional role at 2 hospitals using the revised 23-item Non-TECHnical Skills (NOTECHS) and its subscales (communication, situational awareness, team skills, leadership and decision-making). Over 6 months, 2 trained observers evaluated teams’ NTS using a structured form. Interobserver agreement across hospitals ranged from 86% to 95%. Multiple regression models were developed to describe associations between operative time, team membership, miscommunications, interruptions, and total NOTECHS and subscale scores.ResultsWe observed 161 surgical procedures across 8 teams. The total amount of explained variance in NOTECHS and its 5 subscales ranged from 14% (adjusted R2 0.12, p<0.001) to 24% (adjusted R2 0.22, p<0.001). In all models, inverse relationships between the total number of miscommunications and total number of interruptions and teams’ NTS were observed.ConclusionsMiscommunications and interruptions impact on team NTS performance.

The results support the hypothesis that repeated bouts of venous hypertension during strenuous exercise cause regional vein wall remodelling and collagen accumulation, venous occlusion and pulmonary capillary hypertension. Subjected to these high pressures, there is capillary stress failure, bleeding, haemosiderin accumulation and, subsequently, lung fibrosis.

Summary Reasons for performing study: Sclerosis of the third carpal bone is a common radiographic finding in both lame and sound racehorses, but there are no guidelines correlating degree of sclerosis and incidence of lameness. Objectives: To develop a protocol for describing subchondral bone sclerosis in C3 on dorsoproximal‐dorsodistal oblique (DPr‐DDiO) radiographs of the carpus and to correlate these changes with exercise history and carpal lameness. Methods: One hundred and six Standardbreds entering their first year of training (exercise group) and 7 age‐matched Standardbreds at pasture (controls) were examined at approximately 3 month intervals over 12‐18 months. Examinations consisted of lameness evaluation and carpal radiographs (DPr‐DDiO and flexed lateromedial projections). A grading system (very mild, mild, moderate and severe) for C3 sclerosis seen on the DPr‐DDiO radiograph was developed that utilised a combination of the criteria of trabecular thickening (trabecular score; TS) and total percent area of the C3 radial facet affected (TAA). Results: Exercise group horses showed significant increase in TS and TAA throughout training compared to control horses. Middle carpal joint lameness developed in 32/106 (30%) exercise group horses and none of the control horses. Incidence of middle carpal joint (MCJ) lameness was lower in horses with mild (2/30, 6.7%) than moderate (10/32, 31.2%) and severe (20/44, 45.4%) sclerosis throughout training. Conclusions: Horses with higher grades of sclerosis, as defined by this novel grading system, were more likely to develop MCJ lameness at some point of training. The proposed grading system gave a quantitative assessment of radiographic sclerosis that could then be used to correlate increasing severity of sclerosis with increasing incidences of lameness. Potential relevance: These results serve as a basis for further investigation into determining the degree of C3 sclerosis at which pathological changes and lameness can be expected.