EQUINE VETERINARY EDUCATION / AE / MAY 2015
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Clinical Commentary Milk regurgitation caused by oesophageal stricture in foals
S. K. Reed Department of Veterinary Medicine and Surgery, University of Missouri, USA. Corresponding author email:
reedsk@missouri.edu
The case reports by Berlin et al. (2015) and Bezdekova et al. (201 ) focus on the diagnosis of congenital oesophageal stricture in 2 foals less than one month of age. While the clinical presentation of these patients was similar, the individual nuances of the cases created 2 very different outcomes with one foal responding to noninvasive balloon dilation of the constriction and one foal that was subjected to euthanasia with multiple constrictions complicated by megaoesophagus. Published reports on congenital oesophageal strictures in foals are scarce with only a few case reports (Barber et al. 1983; Clabough et al. 1991; Rohrbach 1980) and a small case series in the literature (Knottenbelt et al. 1992). This paucity of publication indicates that the disease is rare but anecdotal discussion suggests it is common enough that clinicians may encounter it at least once in a career dealing with equines. Awareness of the possibility of this dysfunction will help the clinician to diagnose the problem in affected animals and offer possible treatment.
Oesophageal constriction in foals 5
Working through milk regurgitation differentials
Foals presenting with a primary complaint of significant regurgitation of milk will often have several other complicating issues including dehydration, lethargy and weakness, fever, tachypnoea, respiratory disease and hypoglycaemia, etc. The difficulty in managing these cases is stabilising the patient effectively in order to diagnose the inciting cause of the milk regurgitation and offer possible treatment. The entire route of travel of milk from the mouth to the stomach can contain the source for milk regurgitation and should be considered. Cleft palate, epiglottic dysfunction, physical epiglottic anomalies such as cysts, laryngeal dysfunction, hyperkalaemic periodic paralysis (HYPP)-induced pharyngeal collapse or spasm, branchial cysts, oesophageal disorders (megaoesophagus, intramural obstruction, extramural pressure or constricture, muscular hypertrophy etc) and stomach disorders such as ulceration and reflux are just a few conditions on the list. The daunting number of differentials possible for the singular issue of milk regurgitation emphasise the importance for the clinician to perform the initial physical examination and diagnostics in a way that allows for the elimination of as many possible differentials with the least amount of stress and initial expense.
Diagnostics, particularly potentially stressful or expensive
diagnostics, should only be undertaken on stable patients as there is minimal point in diagnosing a complicated vascular anomaly in a foal using sophisticated and expensive advanced diagnostics such as MRI only to lose the foal from respiratory instability under general anaesthesia. Careful physical examination is the first step as issues such as rostral cleft palates and oesophageal distension may be noted relatively early in the process. Routine blood work including
IgG measurements, complete blood count and serum chemistry may be helpful in assessing the overall status of the foal, some of the expected treatment needs and resulting expenses for stabilisation of underlying conditions. Thoracic radiographs were taken in both of these cases, most likely in light of the underlying respiratory issues identified on initial physical examination. Noncontrast radiographs may identify some conditions causing milk regurgitation such as thoracic masses leading to extramural oesophageal compression or severe megaoesophagus. Awake endoscopy of the nasal passages, pharynx, larynx, oesophagus and stomach in foals stable enough to undergo the procedure will yield the most amount of information regarding differentials for milk regurgitation as it allows for visualisation of many of the structures that could be implicated in milk regurgitation. In addition to more rostral/oral deficiencies, endoscopic examination is very helpful in the initial identification of esophageal disorders (Fig 1), although there is some minor difficulty in differentiating normal motility and peristalsis from possible stricture. The use of contrast cervical and thoracic radiography (Fig 2), including double contrast radiography, can be helpful in confirming disease of the oesophagus in foals (Clabough et al. 1991). The interpretation of oesophageal disease based on thoracic radiographs can be made more difficult in the face of secondary aspiration pneumonia. There are several structures that can impinge on the oesophagus on its course to the stomach. The oesophagus generally courses dorsal and to the left of the trachea in the cervical region and then to the mediastinum still dorsal to the trachea, crossing to the right of the aortic arch at the dorsal aspect of the heart
Fig 1: Endoscopic examination of the oesophagus of a foal with dilation of the oesophagus leading to a stricture at the base of the dilation rather than a continuation of the lumen of the distal oesophagus.
© 2015 EVJ Ltd
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