Equine atypical myopathy: a review

Abstract Atypical myopathy (AM) is an acute rhabdomyolysis syndrome that occurs at irregular intervals in grazing equines. An increasing number of outbreaks have been reported in recent years, including some from countries where the disease has not previously been diagnosed. In this review, clinical and other details of outbreaks of AM are analysed to better define its epidemiological profile. Potential aetiologies are discussed, the short clinical course of AM is described and the main biochemical and pathological findings are considered. Recommendations for medical management are suggested, based on a review of clinical reports. Biochemical and histopathological findings have been integrated in order to characterise the physiopathology of AM. There is an ongoing requirement to record new cases of this syndrome, ideally through an epidemiological network

Prolonged Recovery From General Anesthesia Possibly Related to Persistent Hypoxemia in a Draft Horse

Horses are susceptible to developing large areas of pulmonary atelectasis during recumbency and anesthesia. The subsequent pulmonary shunt is responsible for significant impairment of oxygenation. Since ventilation perfusion mismatch persists into the post-operative period, hypoxemia remains an important concern in the recovery stall. This case report describes the diagnosis and supportive therapy of persistent hypoxemia in a 914 kg draft horse after isoflurane anesthesia. It highlights how challenging it can be to deal with hypoxemia after disconnection from the anesthesia machine and how life-threatening it can become if refractory to treatment. Furthermore, it stresses the point on the interactions between hypoxemia and other factors, such as residual drug effects and hypothermia, that should also be considered in the case of delayed recovery from general anesthesia

Synoviocytes, not chondrocytes, release free radicals after cycles of anoxia/re-oxygenation

peer reviewedBy oxymetry and electron paramagnetic resonance (EPR), we investigated the effects of repeated anoxia/re-oxygenation (A/R) periods on the respiration and production of free radicals by synoviocytes (rabbit HIG-82 cell line and primary equine synoviocytes) and equine articular chondrocytes. Three periods of 20 min anoxia followed by re-oxygenation were applied to 10(7)cells; O(2) consumption was measured before anoxia and after each re-oxygenation. After the last A/R, cellular free radical formation was investigated by EPR spectroscopy with spin trapping technique (n=3 for each cell line). Both types of synoviocytes showed a high O(2) consumption, which was slowered after anoxia. By EPR with the spin trap POBN, we proved a free radical formation. Results were similar for equine and rabbit synoviocytes. For chondrocytes, we observed a low O(2) consumption, unchanged by anoxia, and no free radical production. These observations suggest an oxidant activity of synoviocytes, potentially important for the onset of osteoarthritis

Effects of Juglone on Neutrophil Degranulation and Myeloperoxidase Activity Related to Equine Laminitis.

Experimental laminitis, characterized by a failure of the dermal-epidermal interface of the foot, can be induced in horses by the oral administration of a black walnut extract (BWE). In the early phase of this severe and painful disease, an activation of neutrophil occurs, with the release of myeloperoxidase (MPO), a pro-oxidant enzyme of neutrophils, in plasma, skin, and laminar tissue. Juglone, a naphthoquinone derivative endowed with redox properties, is found in walnuts and has been incriminated in this neutrophil activation. We report for the first time the inhibitory activity of juglone on the degranulation of neutrophils induced by cytochalasin B and formyl-methionyl-leucyl-phenylalanine as monitored by the MPO release (>90% inhibition for 25 and 50 μM). Moreover, it also acts on the peroxidase activity of MPO by interacting with the intermediate "π cation radical," as evidenced by the classical and specific immunological extraction followed by enzymatic detection (SIEFED) assays. These results are confirmed by a docking study showing the perfect positioning of juglone in the MPO enzyme active site and its interaction with one of the amino acids (Arg-239) of MPO apoprotein. By chemiluminescence and electron paramagnetic resonance techniques, we demonstrated that juglone inhibited reactive oxygen species (ROS) and superoxide anion free radical produced from phorbol myristate acetate (PMA)-activated polymorphonuclear neutrophils (PMNs). These results indicate that juglone is not the trigger for equine laminitis, at least if we focus on the modulation of neutrophil activation

Production of Free Radicals and Oxygen Consumption by Primary Equine Endothelial Cells During Anoxia-Reoxygenation

The endothelium plays an active role in ischemia/reperfusion injuries. Herein, we report the effect of a single or successive cycles of anoxia/reoxygenation (A/R) on the mitochondrial respiratory function of equine endothelial cells (cultured from carotids) monitored by high resolution oxymetry, and on their production of reactive oxygen species (ROS). ROS were measured by electron paramagnetic resonance (ESR) using POBN and DMPO spin traps, and by gas chromatography (GC) of ethylene released by ROS-induced α-keto-γ-(methylthio)butyric acid (KMB) oxidation. The oxygen consumption significantly decreased with the number of A/R cycles, and POBN-ESR spectra were specific of adducts formed in the cells from superoxide anion. After a one-hour A/R cycle, high intensity DMPO-ESR spectra were observed and assigned to superoxide anion trapping; the GC results confirmed an important production of ROS compared to normoxic cells. These results show that A/R induces mitochondrial alterations in endothelial cells, and strongly stimulates their oxidative activity as demonstrated by ESR and GC methods

Proceedings 3rd ECVSMR congress

peer reviewe

Comparative Effects of University of Wisconsin and Euro-Collins Solutions on Pulmonary Mitochondrial Function after Ischemia and Reperfusion

peer reviewedBACKGROUND: The aim of this study was to compare the effects of Euro-Collins and University of Wisconsin solutions on pulmonary mitochondrial function after cold ischemia and subsequent warm reperfusion. METHODS: Seventeen pigs underwent lung harvesting after classical lung flush with either University of Wisconsin or Euro-Collins solutions. The mitochondria were isolated from fresh swine lungs, from swine lungs subjected to 24 hr of cold ischemia, and from swine lungs subjected to 24 hr of ischemia followed by 30 min of subsequent ex vivo reperfusion at 37 degrees C with Krebs-Henseleit buffer solution and air ventilation. Mitochondrial oxidative phosphorylation parameters were determined in isolated mitochondria by in vitro measurement of oxygen consumption rates. During reperfusion, the lung function was assessed by the pulmonary aerodynamic parameters and the pulmonary vascular resistance. RESULTS: Relative to controls, mitochondria submitted to cold ischemia showed an alteration in the oxidoreductase activities of the respiratory chain. However, the yield of oxidative phosphorylation was conserved. After reperfusion, pulmonary mitochondria underwent a significant worsening in the oxidoreductase activities of the respiratory chain, and a decrease in the respiratory control and the efficiency of oxidative phosphorylation. Meanwhile, the reperfused lungs showed evidence of early dysfunction, assessed by the aerodynamic parameters and pulmonary vascular resistance. In this model, there was no advantage of University of Wisconsin solution over Euro-Collins solution. CONCLUSIONS: The mild mitochondrial alterations after cold ischemia were not sufficient to explain the limited tolerance of lung to ischemia. After reperfusion, the mitochondrial damage was more severe and could be involved in the posttransplant lung dysfunction

Can we predict troubles during horse clinical examination by a simple test?

Peer reviewe

Prevalence of osteochondrosis in Warmblood horses in Wallonia

peer reviewedOsteochondrosis (OC), a developmental orthopaedic disease, is consecutive to a defect in the endochondral ossification process, and can result in formation of an osteochondral fragment (osteochondrosis dissecans). Our objective is to establish the prevalence of osteochondrosis in Wallonia, and describe the main observed lesions. One hundred forty-two Warmblood horses, aged from 12 to 36 months, underwent a systematic X-ray examination. Sixty-three of these horses (44.4 %) presented one or more OC lesions, 46 (32.4 %) of them with an articular fragment. This prevalence is similar to those observed in Dutch Warmblood horses (44.3 %). The localisation of the lesions was as follows: 25 (17.6 %) of the experimental group showed one or more lesions in the hindlimbs fetlocks, 23 (16.2 %) in the hocks, 21 (14.8 %) in the stifles and 14 (9.9 %) in the forelimbs fetlocks. The medial ridge of the talus is the most frequently injured anatomical site in our study. This lesion was observed in 12 horses (8.4 %), a prevalence that is by far higher than those observed in Dutch Warmblood horses (2.9 %). Not any significant difference was observed between males and females. The high prevalence and the clinical and economic consequences of this disease in the horse’s industry fully justify further research in order to improve the understanding of its pathogenic process.Ann. Méd. Vét., 2008, 152 (3), pp 131-137 Prévalence de l’ostéochondrose chez le cheval de sport en Wallonie VANDER HEYDEN L., SERTEYN D., CAUDRON I., VERWILGHEN D., DELIEGE B., LEJEUNE J.-P. Résumé : L’ostéochondrose (OC) est une affection ostéo-articulaire juvénile, consécutive à une non-ossification de l’os endochondral et pouvant entraîner la présence de fragments ostéochondraux (ostéochondrose dissécante). L’objectif de notre étude est d’établir la prévalence de cette affection en région wallonne, et de décrire les principales lésions observées. Cent quarante-deux poulains de sport nés en Wallonie, âgés de 12 à 36 mois, ont été radiographiés. Soixante-trois de ces poulains (44,4 %) montrent une ou plusieurs lésions d’OC, 46 (32,4 %) d’entre eux avec un fragment articulaire. Cette prévalence est assez proche de celle observée chez les chevaux demi-sang néerlandais (44,3 %). Au niveau localisation, vingt-cinq (17,6 %) de nos chevaux montrent une ou plusieurs lésions au niveau des boulets postérieurs, vingttrois (16,2 %) au niveau des jarrets, vingt-et-un (14,8 %) au niveau des grassets et quatorze (9,9 %) au niveau des boulets antérieurs. La lèvre médiale de la trochlée du talus est le site anatomique du jarret présentant le plus de lésions d’OC avec douze poulains atteints (8,4 %) ; cette proportion est nettement supérieure aux 2,9 % observées chez les demi-sang néerlandais (Vos, 2008). Aucune différence significative n’a été observée entre les mâles et les femelles. La prévalence élevée et les répercussions importantes de cette affection, tant du point vue clinique qu’économique dans la filière équine, justifient pleinement l’approfondissement des études qui sont réalisées sur le sujet

Histology of two rice bodies isolated from the stifle of an adult draught horse stallion

In the human and equine species, different kinds of free floating intra-articular particles are related to certain disorders. Osteochondral fragments formed during osteochondrosis dissecans are the most common finding in the equine species, whereas in humans rice bodies due to rheumatoid arthritis are more frequent. Herein we report a third type of floating body inside the stifle of an adult draught horse stallion, in macroscopic appearance similar to articular rice bodies known in humans. As revealed by histologic examination, the two particles consist of polypoid degenerated structures derived from synovial villi. Their formation was probably induced by ischemia