36 Dysphagia

Dysphagia is difficulty chewing and/or swallowing.

Pathophysiology

General types of dysphagia are classified as oral, pharyngeal or cricopharyngeal.   They can also be grouped as 1) pain, 2) neuromuscular, 3) obstructive and 4) mechanical (similar to pain).

Patients with dysphagia will present for

• Gagging
• Difficulty drinking
• Unable to make a food bolus
• Ineffective swallowing
• Drooling
• Dropping food
• Nasal discharge or cough

Normal chewing requires cranial nerve V, non-painful dentition, chewable feedstuffs and normal musculature. Dental disorders are  a common cause of dysphagia. Abnormal tongue function, painful or nonfunctional muscles and neuropathies can also affect prehension and chewing.

Swallowing requires central stimulation and involves opening of the upper esophageal sphincter, movement of the soft palate upwards to close off the nostrils and retroflexion of the epiglottis to cover the airway. Cranial nerves IX, X and XII are all involved. Problems with any of those steps can lead to dysphagia and dropped food.

Diagnostics

*Consider rabies and wear protective gear*.

Watch the animal eat or drink.

Usually prehension abnormalities are easy to identify as the food or water never makes it into the mouth.  Asymmetrical chewing or dropping of unchewed food particles (quidding) are commonly seen with painful chewing. Basically what goes in is what falls out. 

Oral exams and cranial nerve evaluations

These are crucial to localize lesions. Check for tongue and tooth abnormalities as well as foreign bodies or masses. Full evaluation of cranial nerves is important.

2M antibody titers

Check the animal’s antibody titer to specific muscle groups in the masticatory muscles to see if they have developed an immune response.

Advanced diagnostics

If there are no visible oral lesions or obvious tooth decay, consider dental radiographs and videoendoscopy. Biopsy any masses observed. Referral may be needed for testing and/or therapy. Diagnostics include barium swallows, cranial nerve exams, CT exams (computed tomography) and endoscopy.

Therapy

Dysphagia is generally not an emergency unless patients are dehydrated or in respiratory distress.

Surgical repair is indicated for forms of trauma (jaw fracture, tooth fracture). Extracting painful teeth can rapidly resolve issues. Surgical myotomy is indicated for cricopharyngeal achalasia (failure of the upper esophageal sphincter to relax) and arterial occlusion for equine guttural pouch mycoses (fungal infection that affects the nerves involved in swallowing).

Ruminants may have significant metabolic acidosis and dehydration from salivary loss. Both small and large patients may need re-hydration and slurry or nasoesophageal feeding, as well.

Aspiration pneumonia is common in dysphagia cases as the food goes down the trachea instead of the esophagus; antibiotic therapy is required.

Many types of dysphagia can only be treated supportively; for many, there is no available treatment and supportive care is often lifelong.

Just for fun

Polymyositis dysphagia case- be sure to look up the terms and conditions described

Achalasia dogs – do more review on this one too!

Barium swallow in a person– mostly normal

Barium swallow – esophageal pathologies– description of a variety of images (human)

Swallowing disorders and achalasia – description of the pathophysiology (human)

Megaesophagus in dogs – proceedings