EQUINE VETERINARY EDUCATION / AE / FEBRUARY 2018


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once without further consequences. Two horses (7.41%; simple intraluminal obstruction and reflux oesophagitis) were subjected to euthanasia as a consequence of the diagnosed disorder. Long-term survival within a group of all oesophageal cases was 65.78%.


Discussion


The prevalence of equine oesophageal disorders in our retrospective study was 0.56% of all cases admitted by referral to the clinic during the 5-year period. Breuer et al. (2011) published a 2.4% prevalence of equine simple oesophageal obstruction in the retrospective study of referred cases. Although simple oesophageal obstruction represented >50% of all oesophageal cases in our study, the other disorders (other than simple obstruction) constitute the greater part of the studied group in comparison with previously published results from referral clinics (Feige et al. 2000; Breuer et al. 2011). This difference could be because of a higher number of oesophageal obstructions treated in the field, because owners could have financial constraints and the referral horse population could vary between different countries. The breed and age distribution was similar to the general


hospital population in our study. There are some oesophageal disorders with suspected or proven breed predisposition. Duncanson (2006) and Breuer et al. (2011) suggest that pony breeds are more prone to primary oesophageal obstruction. The pony was represented by only one individual in our group, but ponies are infrequently presented to our clinic. Friesian horses are predisposed to idiopathic megaoesophagus and they appear to suffer from clinically relevant idiopathic hypertrophy of the distal oesophagus (Broekman and Kuiper 2002; Benders et al. 2004; Boerma and Sloet Oldruitenborgh- Oosterbaan 2008). Our group of horses included one male Friesian with idiopathic megaoesophagus and the other with post-obstructive oesophageal stricture. Common aetiological factors were identified in all groups


except for idiopathic megaoesophagus, oesophageal diverticulum and communication between the oesophagus and the guttural pouch. Unfortunately, those results are less significant due to the low number of representative cases within each group other than oesophageal obstruction. The simple oesophageal obstruction was limited to food or shavings impaction, which is frequently described (Craig et al. 1989; Feige et al. 2000; Duncanson 2006). Interestingly, foreign bodies or inappropriate feed items were not found in our study. This differs from the study of Craig et al. (1989) and it is the reason for the absence of surgical treatment of oesophageal obstruction in our group. Dental abnormalities have been shown to be important in simple oesophageal obstruction aetiology because of inadequate chewing (Craig et al. 1989; Duncanson 2006). Dental pathology data were missing in our study possibly because of a lack of stomatological examination or incomplete medical records. Nonsurgical treatment has been attempted in all simple


oesophageal obstruction cases and, apart from one, was successful. General anaesthesia was considered to be helpful in some refractory cases of oesophageal obstruction (Craig et al. 1989). The only simple obstruction nonsurvivor in our group was flushed under general anaesthesia and did not recover from it, because of cardiac arrest. The poor prognosis due to post-anaesthetic respiratory complication was referred to by Duncanson (2006). Current recommendations are that


lavage is not attempted under general anaesthesia due to risk of significant complications (Duncanson 2006; Bezdekova 2012). A common human oesophageal disorder is gastro-


oesophageal reflux disease with or without oesophageal inflammation. Its prevalence varies between 9 and 42% (Delaney 2004). There is some suggestion that highly prevalent equine gastric squamous ulceration is comparable to human gastro-oesophageal reflux disease due to the anatomical similarity of location of lesions dorsal to the margo plicatus, but the equine oesophagus is not always co-affected. The differences between horses and people (apart from the unique stomach anatomy) are equine physiology, different diet and lack of evidence of convincing Helicobacter infection in horses (Collier and Stoneham 1997). Although oesophagitis was the second most common condition in our study, its prevalence is low and only three out of five presented cases had reflux aetiology. Equine reflux oesophagitis is a rare condition and it follows pyloric or duodenal stenosis and delayed gastric emptying (Rebhun et al. 1982). Oesophageal stricture occurs more often in foals (Craig


et al. 1989; Chiavaccini and Hassel 2010). The number of strictures was low in our study, but two of the three cases were yearlings. Concerning the external blunt trauma in the aetiology, it could be suggested that there is a higher probability of kicks by another individual in the herd of yearlings than in mature performance horses kept separately. An excellent prognosis was recorded in surgical treatment of mural type 1 stricture, which contains external oesophageal layers in our study. Both affected horses were treated by oesophagomyotomy with oesophagopexy described by Lillich et al. (2001) and survived long term. The anular ring case (type 3) was complicated by a re-stricture which failed to respond to balloon dilation as well as to bouginage despite treatment attempts being applied over a long period. The poor prognosis in similar cases was also reported by Craig et al. (1989). Oesophageal rupture can follow long-term obstruction,


internal or external trauma (Fubini 2002; Stick 2006). In contrast to the study by Craig et al. (1989) we did not find any nasogastric tube trauma as a cause of oesophageal rupture. That study was performed 30 years ago and the tube material and/or method of tube insertion could be different nowadays, or the rupture could happen after long-term obstruction with ischaemic necrosis of the oesophageal wall. Two of our cases were preceded by blunt neck trauma, which was also a suspected reason in a case study of Kruger and Davis (2013). One of our rupture cases survived, but it represented the longest time of hospitalisation of all our cases. Oesophageal perforation was the only condition complicated by cellulitis and/or mediastinitis because of perioesophageal tissue contamination by food, water, air and saliva, which may migrate to the mediastinum and pleural space through fascial planes (Freeman 1989). False oesophageal diverticulum was identified only once


in our study and it was located in the neck. In this case, the mucosal damage was thought to be due to chronic food impaction in the diverticulum lumen was found, similar to other published cases (Craig et al. 1989; Breuer et al. 2011). Feige et al. (2000) and Breuer et al. (2011) described poor prognosis in three oesophageal diverticulum cases, but Craig et al. (1989) found better follow-up in surgically as well as nonsurgically managed diverticula. The horse in our study


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