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Diagnosis and Treatment of Dysphagia Fjeldborg, J. DVM, PhD, Associate professor(1) and Keith E. Baptiste(2), BVMS, PhD, Dip. ACVIM, Dip. ECEIM Department of Large Animal Science, Large Animal Surgery(1) and Internal Medicine(2), Faculty of Life Science, University of Copenhagen, Denmark Dysphagia is defined as difficulties in swallowing but is often used more broadly to describe problems with eating (i.e. prehension, mastication, swallowing and esophageal transport). A horse with dysphagia has as a consequence the inability but not the unwillingness to eat. Dysphagia can be either 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 more than 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 are more acidic. Therefore a thorough clinical examination is a must, but sometimes it can be very difficult to find the reason for dysphagia. 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, ultrasonography). 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 and neck extension with swallowing attempts. 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 is indicators of aspiration pneumonia. The oral cavity should first be examined with the aid of mouth speculum for signs of dental problems, foreign bodies, tongue injuries or neoplasia. An important valuable assessment is to watch the horse eat and drink. Some horses can continue to drink despite dysphagia. This will also help distinguish between dysphagia and anorexia, since dysphagic horses usually have a voracious appetite. Problems with prehension can also suggest a neurologic problem. Also, ingestion of Russian knapweed or yellow star thistle causes nerve ganglia lesions (nigropallidal encephalomalacia) leaving the horse unable to prehend food due to lack of co-ordination of the lips and tongue. Functional causes of dysphagia are more difficult to diagnose but should be consider if suspicious of a neurologic or neuromuscular disorder. The initial step should be to perform a full neurologic examination. Swallowing function (deglutition) can be assessed by observing the horse eat, passing a stomach tube or during endoscopy. Endoscopy is an extremely valuable tool in evaluating dysphagia and should include examination of the nasopharynx, guttural pouches, trachea and first half of the length of esophagus. Preferably the endoscopy should be performed without sedation as sedation can adversely affect swallowing. Radiographs may be useful to assess bony structures of the head and throat. This can be added with contrast radiographs to follow the swallowing process. Ultrasound can help in examining the retropharyngeal space and cervical portion of the esophagus. Causes of Dysphagia As mentioned earlier there are more than 109 possible reasons for dysphagia in the horse, some of which are mentioned below. Oral Cavity NasoPharynx/Guttural pouches Esophagus Tooth root abscess Broken teeth Peridontal disease Abnormal dentition / wear Stomatitis/glossitis - NSAID toxicity - Thrush - Vesicular diseases Trauma (buccal, gingival, tongue) Foreign bodies Mandibular trauma/fracture Temporomandibular osteopathy Neoplasia Yellow star thistle poisoning Russian knapweed Tetanus Polyneuritis equi Iatrogenic Retropharyngeal abscess Guttural Pouches - Stylohyoid osteopathy - Rectus capitus rupture - Tympany - Mycosis - Empyema - Petrous temporal bone fracture Neuromuscular - HYPP - White muscle disease - Polysaccharide storage disease - Hypocalcemia - Myotonia - White snakeroot toxicity Neoplasia Post surgical laryngo-plasty Pharyngeal/epiglottic cysts Pharyngeal abscess DDSP Displaced palatopharyngeal arch (4. branchial defect) Cleft palate Severe pharyngitis Lead poisoning Botulism Encephalitis (viral, bacterial, parasitic) Cerebral/brainstem edema/hemorrhage Intracranial masses Grass sickness Equine protozoal myeloencephalitis Tetanus Hepatocephalopathy Iatrogenic Leukoencephalomalacia Organophosphate poisoning Obstruction (Choke) Lead poisoning Botulism Megaesophagus Grass sickness Neoplasia Rupture Cysts Tetanus Proximal duodenitis/jejunitis Iatrogenic Esophageal ruptures Fistula Cysts Megaesophagus Neoplasia Idiopathic Treatment Treatment of dysphagia is highly variable and depends on the inciting cause. First of all the owner should be advised initially to withdraw all feed material and water to avoid the risk of aspiration pneumonia. Treatment can be medical, surgical, through management but in some cases, no treatment is possible. However, many of these cases require intensive management. One should avoid feeding roughage to horses with dysphagia, and instead feed slurries made from complete pelleted feeds (maybe via a stomach tube). Longterm dysphagia may lead to major electrolytes losses in saliva leading metabolic acidosis, hyponatremia, and hypochloremia. Therefore the horse has to be monitored carefully. Some causes of dysphagia Obstruction (Choke) Choke is defined as an inability to move ingesta to the stomach due to a partial or complete obstruction of the esophagus lumen. The reason can be primary and due to a feed impaction or secondary due to other diseases. Esophageal obstruction is an emergency and should be treated as soon as possible. In most cases medical treatment is successful and sometimes in combination with passing a stomach tube and esophageal lavage. Sedation with xylazine can be of advantage as it also relax the muscles of the esophagus. In a few cases surgery is necessary, but the prognosis is often poor due to secondary esophageal strictures after surgery. Retropharyngeal abscess Retropharyngeal abscesses are often due to Streptococcus spp. The symptoms can be fever, dysphagia, abnormal breathing noises and coughing. If the horse shows dyspnea, then a temporary tracheostomy can be indicated. In many cases an effective treatment will be nonsteroidal anti-inflammatory agents and systemic penicillin. If the abscess is well encapsulated then it can be drained under the guidance of ultrasonography. The prognosis depends on the severity of the disease. Sometimes the lymph nodes can drain into the guttural pouches and damage to the nerves in this area leading to dysphagia. Subepiglottical cysts Subepiglottical cysts are suspected to arise from remnants of the thyroglossal duct. Clinical signs include respiratory noise and exercise intolerance. Large cysts may produce coughing, dysphagia, and aspiration. Diagnosis is confirmed by endoscopy of the upper respiratory tract. Treatment involves complete removal of the secretory lining of the cyst either by laser or surgical through a laryngotomy approach. The prognosis is good. Pharyngeal lymphoid hyperplasia (PLH) PLH is a common condition in the young horse and naturally regresses as the horse ages. Occasionally follicles enlarged and coalesce with surrounding follicles. In these situations, follicles may appear hyperemic or inflamed and may exude mucoid or mucopurulent material. Signs of pharyngeal pain include reduced appetite, frequent swallowing and/or dysphagia. In most cases treatment is not necessary though rest and NSAID administration are warranted in horses demonstrating pharyngeal pain. Dorsal dislocation of the soft palate (DDSP) DDSP with dysphagia is a permanent anomaly and due to neurological reasons. The symptoms are dysphagia and coughing. There is no cure for this disease.