Abstract
BackgroundIn horses a number of small intestinal diseases is potentially life threatening. Among them are Equine Grass Sickness (EGS), which is characterised by enteric neurodegeneration of unknown aetiology, as well as reperfusion injury of ischaemic intestine (I/R), and post-operative ileus (POI), common after colic surgery. The perfusion of isolated organs is successfully used to minimize animal testing for the study of pathophysiology in other scenarios. However, extracorporeal perfusion of equine ileum sourced from horses slaughtered for meat production has not yet been described. Therefore the present study evaluated the potential of such a model for the investigation of small intestinal diseases in an ex vivo and cost-efficient system avoiding experiments in live animals.ResultNine ileum specimens were sourced from horses aged 1–10 years after routine slaughter at a commercial abattoir. Ileum perfusion with oxygenated autologous blood and plasma was successfully performed for 4 h in a warm isotonic bath (37.0–37.5 °C). Ileum specimens had good motility and overall pink to red mucosa throughout the experiment; blood parameters indicated good tissue vitality: 82 ± 34 mmHg mean arterial partial pressure of oxygen (pO2) compared to 50 ± 17 mmHg mean venous pO2, 48 ± 10 mmHg mean arterial partial pressure of carbon dioxide (pCO2) compared to 66 ± 7 mmHg venous pCO2 and 9.8 ± 2.8 mmol/L mean arterial lactate compared to 11.6 ± 2.7 mmol/L venous lactate. There was a mild increase in ileum mass reaching 105 ± 7.5% of the pre-perfusion mass after 4 hours. Histology of haematoxylin and eosin stained biopsy samples taken at the end of perfusion showed on average 99% (±1%) histologically normal neurons in the submucosal plexus and 76.1% (±23.9%) histologically normal neurons in the myenteric plexus and were not significantly different to control biopsies.ConclusionExtracorporeal, normothermic perfusion of equine ileum over 4 h using autologous oxygenated blood/plasma perfusate showed potential as experimental model to test whether haematogenous or intestinal exposure to neurotoxins suspected in the pathogenesis of EGS can induce neuronal damage typical for EGS. Also, this model may allow investigations into the effect of pharmaceuticals on I/R injury, as well as into the pathogenesis of equine POI.
Highlights
In horses a number of small intestinal diseases is potentially life threatening
Animals Nine horses were selected as ileum donors
Perfusion The time between slaughter and ileum isolation and cannulation, i.e. warm ischemia time was between 29 min and 51 min and cold ischemia time was between 186 min and 330 min
Summary
In horses a number of small intestinal diseases is potentially life threatening. Among them are Equine Grass Sickness (EGS), which is characterised by enteric neurodegeneration of unknown aetiology, as well as reperfusion injury of ischaemic intestine (I/R), and post-operative ileus (POI), common after colic surgery. Gastrointestinal diseases are the most common emergency in equine hospitals, with acute colic being the most frequent medical problem requiring surgery in up to 17.5% of cases [1] Life threatening conditions such as Equine Grass Sickness (EGS), ischemia/reperfusion injury (I/R) or post-operative ileus (POI) require further investigation in aetiology, treatment and pathogenesis [1,2,3,4]. Horses are at risk of developing small intestinal POI, a serious condition of reduced or absent intestinal peristalsis without mechanical obstruction Mechanisms of this disease, such as intestinal manipulation, disruption of neuronal or hormonal continuity, or effects of pharmaceutical interventions, are mainly proposed based on research in rodents and on its parallels to human ileus; these results may not be directly related to the horse, as human ileus involves both small and large intestine [4]
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