Equine dysphagia: a review of 17 cases

Introduction. Dysphagia is commonly defined as a difficulty in swallowing; for practical purposes and with regard to the anatomy and physiology of the equine upper alimentary tract, this term in the horse is used more broadly to describe problems with eating (i.e. prehension, mastication, swallowing and esophageal transport). There are several possible causes of dysphagia recognised in horses involving the upper digestive tract (oral cavity, pharynx and/or), the muscoloskeletal or the nervous system. Clinical signs vary dipending on the source of the disease and whether dysphagia is the main problem or part of a multi-systemic condition. This report describes 17 cases of equine dysphagia in order to analyze the clinical aspects of the disease and establish the prevalence of the different causes of dysphagia. Description of the case. Clinical features, additional diagnostic tests, therapeutic approach and outcome were described for each case. Clinical findings on admission included coughing (11/17), nasal discharge containing water, saliva or food (9/17), weight loss (6/17), odynophagia (6/17), quidding (3/17), poor performance (1/17). Physical examination revealed fever and evidence of systemic disease (3/17), local swelling and distension of the esophagus (3/17) and signs of inhalation pneumonia (9/17). Endoscopy of the pharynx, larynx and guttural pouches revealed conditions compromising the pharingeal phase of deglutition in 9/17. Esophagoscopy showed evidence of mucosa defects (2/17), and physical or functional obstruction of the esophagus (4/17); fluoroscopic investigation using contrast media showed strictures (2/17) and megaesophagus (2/17). Ultrasonography was performed to investigate a case of septic sialoadenitis (1/17) and to confirm the suspicion of inhalation pneumonia (9/17). Diagnosis was made in all cases. Esophageal disorders were present in 6 horses, including traumatic mucosal ulcerations (2/6), megaesophagus (2/6) and esophageal strictures (2/6). In three horses dysphagia was a complication following laringoplasty (1/3), staphylectomy (1/3) and guttural pouch incision for chondroids removal (1/3). Systemic disease caused dysphagia in 2 horses, one suffering from botulism and the other from meningoencefalomyelitis. Three horses showed local infectious diseases such as guttural pouch mycosis (1/3), laryngeal granuloma caused by Actinobacillus lignierensii (1/3) and septic sialoadenitis (1/3). Neoplasia (oral squamous cell carcinoma) was encountered in one horse; pharyngeal dysfunction due to prematurity occurred in one neonatal foal; 4-BAD syndrome was detected in one adult horse. Medical treatment was performed in all cases; 12 horses required intensive with nutritional support by enteral feeding. One horse underwent surgical treatment with debridment of the parotid gland. 12 horses were discharged and 5 euthanized.Conclusion. In this report, 17 horses referred for dysphagia were affected from 12 different pathological conditions. According to the classification of dysphagia proposed by Reed et al. (2010), 41% of our cases fell into the obstructive category, while 35% belonged to the neurologic one; 18% and 6% entered into the painful and muscolar class of dysphagia respectively. Clinical signs of dysphagia showed a low specificity regarding the site of the disease, since they were observed in patients suffering from different disorders both in the oropharynx and in the esophagus. Coughing, nasal discharge and ptyalism were the symptoms most represented (respectively 61%, 50% and 37% of total symptoms); coughing and nasal discharge were always found in association, with the exception of the neonatal foal with pharyngeal dysfunction, probably due to delay in the development of the coughing reflex. Odynophagia was detected in 35% of dysphagic patients; interestingly, 100% of them had esophageal disorders, thus the presence of this particular symptom could be considered highly suggestive of an esophageal localization. Diagnostic evaluation of dysphagia was complex in all cases; more than 50% of our patients required at least four ancillary procedures. Physical examination alone was not sufficient to achieve the diagnosis in all cases. Treatment and prognosis were variable depending on the inciting cause and complications. Inhalation pneumonia occurred in 50% of our cases, thus it could be considered a significant complication; particular attention should be paid to its prevention in the treatment of dysphagia. Left laryngeal neuropaty (grade IV) was observed in 18% of the patients, all suffering from cervical esophageal stricture. The tight anatomical relation which exists between the esophagus and the left recurrent laryngeal nerve seems to have a key role in the occurrence of this complication.