Equine Internal Medicine Q&A 20

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An eight-year-old gelding is presented with acute colic, abdominal distension, trembling, sweating, tachycardia (heart rate 76bpm) and tachypnoea (respiratory rate 32bpm). The horse had accidentally eaten a large quantity of grain several hours earlier. The mucous membranes are bright red with petechial haemorrhages. Intestinal sounds are absent, and percussion of the abdomen results in high-pitched pings. Colonic distension with tight bands are palpated per rectum. Haematology reveals haemoconcentration (PCV, 0.68l/l), neutropenia (PMN count, 3.7x109/l) with toxic changes in the neutrophils.

Question	Answer		Article
What is the diagnosis and pathogenesis?	Grain overload. Grain engorgement results in rapid fermentation and the production of large amounts of lactic acid, volatile fatty acids and gas in the gastrointestinal tract, leading to gastrointestinal atony and distension. The severe acidosis results in massive endotoxaemia and subsequent circulatory failure (shock). The presence of petechial haemorrhages is suggestive of disseminated intravascular coagulation.		Link to Article
How would you treat this horse?	Intravenous fluid therapy is required to combat circulatory failure. Hypertonic saline may be administered initially, but this must be followed by polyionic fluid (2–4 litres/hour). Plasma may also be beneficial (2–4 litres), preferably hyperimmune plasma containing antibodies against endotoxins. Flunixin meglumine (0.25mg/kg every 8 hours) is given after signs of colic have abated for its anti-endotoxic effects. A nasogastric tube should be passed, and may be left in place to relieve gastric distension. If there is no gastric reflux, activated charcoal may be administered in water via the nasogastric tube. The horse should not be allowed to eat until the clinical signs have improved. Frog pads may be applied to the front feet in an attempt to prevent or minimize the risk of laminitis.		Link to Article
What is the prognosis?	The prognosis for horses with severe clinical signs such as this is poor. The prognosis is particularly poor in cases with severe abdominal pain and abdominal distension, and horses which develop early signs of laminitis.		[[Laminitis l|Link to Article]]