Colic, Gastric Causes

Gastric Causes of Colic

• Gastroduodenal ulceration or 'Equine Gastric Ulcer Syndrome (EGUS)'
• Pyloric obstruction and delayed gastric emptying: pyloric stenosis is a structural resistance to gastric outflow. Congenital pyloric stenosis has been reported in foals and one yearling and results from hypertrophy of the pylroic musculature (135-137). Aquired pyloric stenosis can result form neoplasia or duodenal ulceration(138-141). Clinical signs depend on the degree of obstruction but include abodminal pain, salivation and bruxism. Complete or near-complete obstruction can result in gastric reflux and reflux oesophagitis. In foals with congenital pyloric hypertrophy, clinical signs may begin with the consumption of solid feed. In foals a presumtpive diagnosis can be made with gastric endoscopy and radiography (plain and contrast studies). Depending on the cause and severity of disease, gastric endoscopy may provide a presumptive diagnosis in the adult horse. Measurement of gastric emptying can aid the diagnosis. Several methods of measurement are currently available, including nuclear scintigraphy, acetaminophen absorption, and postconsumptionn[13C]-octanoic acid blood or breath testing (130,142,143). During an exploratory laparotomy, a distended stomach and thickened pylorus are accompanied by a reltively empty intestinal tract. If complete obstruction is not present, medical theray with a prokinetic such as bethanechol can increase the rate of gastric emptying(130). Phenylbutazone and cisapride have also been shown to attenuate the delay in gastric emptying caused by endotoxin administration(142,244). Surgical repair is necessary for definitive treatment of complete or near-complete obstruction and consists of either gastroenterostomy or pyloroplasty(84,131). Pyloric duodenal intussusception has been reported in an adult horse with colic(145).
• Gastric dilation and rupture
• Gastric impaction
• Gastric/pyloric spasm: this commonly affects racehorses, immediately after racing, and is known colloquially as 'racehorse colic'. Typically, the animal will have had access to cold water, but this is not always the case. Although the signs of colic seen may be very violent, this condition is not associated with any risk of gastric rupture. Spasmolytic drugs are ineffective in treatment, however, naso-gastric intubation is immediately curative.
• Neurological atony: a chronic motility dysfunction, leading to a slow filling of the stomach with ingesta. Inhibition of gastric outflow is not normally a feature, and therefore gastric rupture is not a risk. A mild colic may be seen, but far more common is poor condition and reduced performance. Warmblood horses are more commonly affected than other breeds, leading to the suggestion that there may be a genetic component to the disorder.
• Gastric Neoplasia: a malignant squamous carcinoma can effect the cardia and upper squamous regions of the stomach, resulting in a persistent mild colic, commonly seen soon after feeding. Weight loss and general ill health are usually seen, and the prognosis is very poor, due to the high risk of metastasis.