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EQUINE VETERINARY EDUCATION / AE / AUGUST 2020


Arabians and females were found to suffer from FB obstruction more commonly than males and other breeds in the current study. In previous studies, no breed or sex predisposition was found regarding FBs; however, females and Arabians, miniature horses and ponies were found to be affected more commonly by small colon impactions (Dart et al. 1992). Arabian horses may be predisposed to FB obstruction due to their small stature, and they were dominant in this study possibly since in Israel miniature horses and ponies do not represent a significant part of the population. Mean time between onset of clinical signs of colic and


admission was 1.8 days. This represents typical signs of small colon or aboral large colon obstruction with gradual progress of clinical signs (Dart et al. 1992; Schumacher and Mair 2002). It is interesting to note that in spite of the relatively elongated time for admission, most horses underwent surgery on the same day as arrival. Reasons to go to surgery were mainly related to severe pain and inadequate response to conservative treatment, however there were a few cases that showed signs of endotoxaemia development. Moreover, all the cases in which the obstruction was visible, suffered already from injured serosa. Although the clinical presentation of FB obstruction may appear at first as a ‘non-complicated’ impaction, the pressure of the FB on the intestine may result in necrosis and quick deterioration of the animal’s health state. As such, it is our impression that any case suspected to suffer from FB obstruction should be considered as a surgical case more rapidly. The main clinical sign upon presentation was abdominal


distention seen in the majority of cases and decreased or no faecal passage. Moreover, detection of large colon distention was the most common finding during rectal palpation in the current study. The abdominal distention, produced by gas accumulation oral to the FB, is the probable cause for the gastric reflux evident in 38% of the horses. Abdominal distention and the presence of reflux are not an uncommon finding in small colon obstruction or previous reports of FB obstruction (Gay et al. 1979; Ruggles and Ross 1991; Rhoads et al. 1999; Frederico et al. 2006). Recognition of the FB during rectal palpation was evident in only six horses. There may be several reasons for the low FB detection rate during rectal palpation, seen in other studies as well (Boles and Kohn 1977; Gay et al. 1979). One reason is that the high incidence of gas distention could obscure the location of the FB and prevent its detection. The other reason is that the common location of the FB in the oral small colon or aboral large colon is difficult to reach during the examination. The most common location of the FBs was the small


colon followed by the aboral part of the large colon (mainly transverse colon), similar to previous studies (Boles and Kohn 1977; Gay et al. 1979; van Wuijckhuise-Sjouke 1984). The ingested foreign material may remain within the large colon for a significant period of time before obstructing the small colon or tunnel-like structure of the transverse colon (Schumacher and Mair 2002). The surgical inaccessibility of those intestinal segments complicates the removal process and therefore several techniques were developed to prevent contamination while removing the FB (Schumacher and Mair 2002; de Oliveira Dearo et al. 2009; Pierce 2009), as mentioned earlier. When feasible, our first choice of treatment for small colon FBs is high enema which is the least invasive technique since it does not


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include enterotomy or resection. This technique was used in cases when the impacted mass around the foreign material could be dissolved to some extent, decreasing the size of the impaction, eliminating the sharp protrusions and enabling it to be massaged to the anus. High enema was not performed in cases where the FB was well adhered to the intestine wall, the intestine around the FB was compromised or the FB contained rigid projections which could potentially damage the intestine during the manipulation. In those cases, a small colon enterotomy was performed. Due to the less invasive nature of the technique, it will presumably involve less complications post- operatively. However, owing to the small number of horses, this statement could not be confirmed. It has been stated previously that a high enema during surgery may result in inflammation, vascular compromise, peritonitis, adhesions and intestinal rupture (Ruggles and Ross 1991). As such, it has been recommended that a high enema should be performed with extreme caution and an antimicrobial treatment post-operatively against anaerobic bacteria should be initiated (Ruggles and Ross 1991). A high enema can also be advantageous when the FB is located in the transverse colon or oral small colon. Here, the high enema is performed to distend the bowel with fluid and as a consequence the FB can detach from the intestine and move in a retrograde manner to a safe site for enterotomy in the large colon. When applicable, the FB was manipulated in that manner to the pelvic flexure and removed by pelvic flexure enterotomy. If the body was too large, a right dorsal colon enterotomy was performed. In the vast majority of the cases, a pelvic flexure enterotomy was performed as well, to evacuate the large colon. This process presumably enables healing of the segment involved with the FB post-operatively and minimises contamination at the forthcoming enterotomy site (Pierce 2009). An additional benefit of evacuating the large colon in that manner is the removal of smaller FBs, such as twine fragments, which could cause obstructions in the future. Historically, complications following small colon surgeries


are common with an incidence rate reaching up to 80% (Boles and Kohn 1977; Rhoads et al. 1999; Frederico et al. 2006). Diarrhoea and fever are the two most common complications associated with small colon surgery (Rhoads et al. 1999; Frederico et al. 2006; Prange et al. 2010). In the current study, the complication rate was 41% with fever, diarrhoea and incisional infection being most common. Incisional infection is a well-known complication following abdominal surgery and accounted typically for 20–40% of cases, however higher incidence such as 70% was reported in specific circumstances such as repeated surgery (Tnibar et al. 2013; Dunkel et al. 2015; Isgren et al. 2017). The prevalence of incisional site infection in the present study (15%) compares favourably with these studies, particularly when considering the high risk for faecal contamination in FB surgeries which is considered to be a risk factor for incisional infection (Darnaud et al. 2016). Diarrhoea and fever, in cases suffering from small colon pathologies, are common with an incidence of up to 80% (Rhoads et al. 1999; Frederico et al. 2006; de Bont et al. 2013). Some evidence suggests that high enema and pelvic flexure enterotomy may cause diarrhoea due to irritation of the mucosa, however the influence is usually transient (Pierce 2009). In our study, performing a high enema did not increase the incidence of post-operative diarrhoea.


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