Influence of mechanical manipulations on the local inflammatory reaction in the equine colon.

REASONS FOR PERFORMING STUDY: Large intestinal diseases in horses are characterised by inflammation, which could arise from the disease process with some contribution from intestinal manipulation. The effects of the latter are unknown but important to surgeons and could contribute to post operative complications. OBJECTIVES: To characterise type and degree of intestinal inflammation induced by various mechanical stimuli in the equine ascending colon. METHODS: Laparotomy was performed in 12 horses, the left dorsal colon exteriorised and 3 segments randomly exposed to different mechanical manipulations: 1) enterotomy, 2) enterotomy and mucosal irritation and 3) serosal irritation. Intestinal biopsies were harvested before, immediately after and 30 min after each manipulation for histological evaluation. Eosinophils were detected with Luna's stain and neutrophils identified by immunohistochemical staining for calprotectin. Additionally, left dorsal colon samples from 14 horses from a jejunal ischaemia-reperfusion study were collected immediately after laparotomy (7 horses) and at the end of the experiment without previous manipulation of the colon (7 horses). Horses were subjected to euthanasia at the end of both studies. RESULTS: Redistribution of mucosal neutrophils and eosinophils towards the luminal surface and increased neutrophilic infiltration of the submucosa were demonstrated after serosal and mucosal irritation. All manipulations resulted in serosal infiltration with neutrophils. Laparotomy and small intestinal manipulation increased mucosal eosinophilic infiltration. CONCLUSIONS AND POTENTIAL RELEVANCE: Mechanical intestinal manipulation caused a rapid local inflammatory reaction in the mucosa, submucosa and serosa including a mucosal eosinophilic response. These changes could exacerbate existing inflammation in horses with large colon disease. Colic surgery can lead to intestinal inflammation in nonmanipulated intestine and this could contribute to a higher morbidity rate in horses after prolonged colic surgery. An intestinal biopsy should be collected at the beginning of surgery to avoid false interpretations.

The effects of Strongylus vulgaris parasitism on eosinophil distribution and accumulation in equine large intestinal mucosa.

REASONS FOR PERFORMING STUDY: Eosinophilic granulocytes have been associated with parasite or immune-mediated diseases, but their functions in other disease processes remain unclear. Cause and timing of eosinophil migration into the equine gastrointestinal mucosa are also unknown. OBJECTIVE: To determine the effects of intestinal parasitism on eosinophils in equine large intestinal mucosa. METHODS: Large intestinal mucosal samples were collected from horses and ponies (n = 16) from the general veterinary hospital population, ponies (n = 3) raised in a parasite-free environment, ponies experimentally infected with 500 infective Strongylus vulgaris larvae and treated with a proprietary anthelmintic drug (n = 14), and a similar group of ponies (n = 7) that received no anthelmintic treatment. Total eosinophil counts and eosinophil distribution in the mucosa were determined by histological examination. A mixed model analysis was performed and appropriate Bonferroni adjusted P values used for each family of comparisons. P<0.05 was considered significant. RESULTS: There was no difference in large intestinal mucosal eosinophil counts and eosinophil distribution between ponies infected with S. vulgaris and those raised in a parasite-free environment. Experimental infection with S. vulgaris, with or without subsequent anthelmintic treatment, did not change eosinophil counts, and counts were similar to those for horses from the general population. CONCLUSIONS: Migration of eosinophils to the equine large intestinal mucosa appears to be independent of exposure to parasites. Large intestinal mucosal eosinophils may have more functions in addition to their role in defence against parasites.

Total and partial ovariohysterectomy in seven mares.

REASONS FOR PERFORMING STUDY: Ovariohysterectomy appears to have a low mortality rate in mares, but the procedure needs to be reviewed because of the high risk of life-threatening complications. HYPOTHESIS: That ovariohysterectomy can be effective treatment for a variety of uterine diseases in mares and carries a good prognosis. METHODS: Diagnosis, clinical data, surgical technique, post operative care, complications and outcome were recorded from medical records of 7 mares that underwent total (6) and partial (1) ovariohysterectomy at the University of Illinois from 1994 to 2001. RESULTS: The indications for ovariohysterectomy were chronic pyometra (4 mares), chronic uterine torsion (n = 2) and chronic intramural haematoma (n = 1). Surgical exposure was difficult but was improved by traction on stay sutures and right-angled clamps. In some cases, application of the TA-90 autosuture instrument as a right-angled clamp to the caudal part of the uterus improved access to the uterine stump. The most common post operative complications were decreased faecal output, decreased intestinal sounds (4 mares) and mild abdominal pain (2). Two mares had mild to moderate incisional infections. Other previously reported complications, such as haemorrhage, septic peritonitis, uterine stump infection or necrosis, and diarrhoea, did not occur. All mares survived over follow-up periods of 6 months to 5 years and were used for riding (6 mares) and embryo transfer (1 mare, after partial ovariohysterectomy). CONCLUSIONS AND POTENTIAL RELEVANCE: According to this study, the prognosis for mares after ovariohysterectomy appears to be good, despite the technical difficulties of the procedure. The prevalence of life-threatening complications can be lower than reported.