Page 813 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

788 CHAPTER 4

VetBooks.ir Table 4.3 Prokinetic drugs that have been used for the treatment of ileus

DRUG ACTION DOSE
Cisapride Acts on entire GI tract. Oral administration may not be 0.1–0.6 mg/kg p/o q8 h
effective if significant gastric reflux is ongoing. Rectal
administration is not effective. Should not be used in horses
treated with certain drugs such as erythromycin
Erythromycin Improves small- and large-intestinal motility 1 mg/kg in 1 l saline given i/v for 1 hour q6 h
lactobionate
Metoclopramide Improves gastric and proximal small-intestinal motility 0.1 mg/kg/h CRI
Lidocaine May act by reducing the release of catecholamines 1.3 mg/kg i/v bolus over 15 minutes,
systemically, suppressing the reflex inhibition of gut followed by 0.05 mg/kg/min in saline CRI
motility, stimulating smooth muscles directly, or by
decreasing the inflammation locally
Bethanecol Stimulates cholinergic (muscarinic) receptors, resulting in (1) 2.5 mg s/c 2 and 5 hours postoperatively
increased peristaltic activity in the stomach and intestinal (2) 0.025–0.1 mg/kg s/c q6–8 h
tract (3) 0.3–0.4 mg/kg p/o q6–8 h
Neostigmine Competes with acetylcholine for acetylcholinesterase, 0.004–0.022 mg/kg i/v
resulting in accumulation of acetylcholine and increased
intestinal muscle tone

Aetiology/pathophysiology be characterised by intermittent colic, recurrent
Formation of a stricture can be related to an enter- impactions or intestinal tympany.
otomy or intestinal resection and usually occurs at
the surgical site. Stricture can also occur in a site Differential diagnosis
of resolved entrapment, non-perforating duodenal Differential diagnoses, of which there are a variety,
ulceration and possibly from duodenitis/proximal depend on the degree of intestinal obstruction and
jejunitis. Proximal duodenal stricture caused by the location of the stricture.
severe gastroduodenal ulceration is classically found
in foals more than 2 months of age. Those found Diagnosis
at the level of the ileocaecal valve may result from Duodenal stricture
tapeworm injury. Strictures usually result from local Laboratory findings can include dehydration, hypo-
ulceration or inflammation, with subsequent forma- chloraemia, hyponatraemia and azotaemia. Contrast
tion of fibrous tissue. The deposit of fibrous tissue radiography (barium series) will demonstrate a
will eventually remodel and contract, potentially delayed gastric emptying – the barium remains
resulting in decreased lumen diameter. pooled in the stomach for >90 minutes. NG reflux
may be present, but small-intestinal distension is not
Clinical presentation palpable. Endoscopic examination of the gastric and
Clinical presentation varies with the region affected. duodenal mucosa may be useful in order to identify
If a duodenal stricture is present, poor growth, a stricture, the underlying cause or secondary prob-
depression, anorexia, fever, bruxism, reduced gas- lems such as EGUS.
tric emptying, severe equine gastric ulcer syndrome
(EGUS) and intermittent colic may be observed. If Ileal stricture
the ileum is affected, signs can range from chronic A chronic adaptive small-intestinal distension may
mild intermittent colic to, less commonly, severe occur. The increased diameter of the small intestine
peracute colic as with obstructive lesions. Strictures may be palpable p/r or identified ultrasonographi-
at the level of the pelvic flexure or small colon may cally. If total obstruction is present, severe intestinal