Diagnosis and Treatment of Dysphagia

The definition of dysphagia is defined as difficulty in swallowing but is often used more broadly to describe problems with eating (i.e. prehension, mastication, swallowing and esophageal transport). Dysphagia is the inability but not the unwillingness to eat. Dysphagia can be congenital or aquired, the main problem or part of a multi-systemic condition, and dysphagia may be associated with muscular or neurological diseases. There are 109 possible causes of dysphagia recognised in horses that be broken down to disorders involving the oral cavity, pharynx and/or esophagus. Sometimes painful conditions involving these structures can present like dysphagia (e.g. fractured tooth, thrush, vesicular stomatitis, mandibular trauma). Obstructive lesions in the stomach or small intestine can result in reflux of ingesta which can be difficult to distinguish from dysphagia. Material from the esophagus is usually slightly alkaline and ingesta from the stomach is more acidic.

Clinical signs
Clinical signs of dysphagia can vary depending on the source of the problem, but may include ptyalism (excessive salivation), gagging, quidding, nasal discharge and coughing as some of the material may be aspirated into lungs resulting in acute aspiration pneumonia. The nasal discharge will be more apparent with the head lowered, usually within a minute after the ingestion of food or liquids. A horse with dysphagia will in some cases show forceful attempts to swallow accompanied by extension of the head, followed by a forceful flexion and contractions of the muscles at the ventral part of the neck. The basic approach for dysphagia is to assess whether it is due to a functional or morphologic abnormality. Thus, basic requirements include a thorough history, physical examination and additional tests (e.g. endoscopy, radiographs). For example, a history of acute dysphagia is often consistent with trauma, whereas a slow onset is more likely due to a neurologic problem. Toxic substances exposure should also be considered (e.g. lead, yellow star thistle). Clinical signs of oral cavity involvement include quidding or dropping water from the mouth, reluctance to chew, ptyalism or abnormalities in prehension. Pharyngeal and esophageal dysphagias are characterised by coughing, nasal discharge (containing water, saliva or food material), gagging, anxiousness, neck extension with swallowing attempts.
The owner should be advised initially to withdraw all feed material and water to avoid the risk of aspiration pneumonia.

Clinical examination
The clinical examination is focused on the head and neck. Since rabies is a potential cause of dysphagia, then all protective measures should be taken to ensure personal safety!! Also, horses with dysphagia are at a great risk to develop aspiration pneumonia, such that the lungs should be auscultated carefully for abnormal lung sounds. Coughing, abnormal respiration, or nasal discharge are indicators of aspiration pneumonia.  [...]