Download Diagnosis and Treatment of Dysphagia

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.