Lecture 4 1/31/25 Flashcards
What are the characteristics of dysphagia?
-difficult prehension and swallowing
-repeated swallowing
-ptyalism/drooling
-localizes to oral cavity or pharynx
What are the characteristics of regurgitation?
-passive expulsion of non-digested food and flood
-typically occurs soon after a meal
-localizes to esophagus
What are the characteristics of vomiting?
-forceful, active expulsion of material
-preceded by salivation, retching, and abdominal contractions
-localizes to stomach and/or small intestine
What is swallowing/deglutition?
complex reflex that moves food and fluids into the GI tract while avoiding the resp. tract
What are the 4 phases of swallowing?
-oral phase
-pharyngeal phase
-esophageal phase
-gastroesophageal phase
What are the characteristics of the oral phase of swallowing?
-voluntary
-food enters oral cavity
-chewing and bolus formation occur
-tongue elevates and propels bolus into pharynx
What are the characteristics of the pharyngeal phase of swallowing?
-involuntary
-bolus presence in caudal pharynx stimulates mechanoreceptors to send signals to the brainstem
-soft palate elevates to seal nasopharynx
-larynx and hyoid bone move forward and upwards
-epiglottis moves back and down to stop respiration
-cricopharyngeal stage occurs in this phase
What is the cricopharyngeal stage?
-contraction of the thyropharyngeal muscle
-relaxation of the cricopharyngeal muscle
-part of the pharyngeal phase?
What are the characteristics of the esophageal and gastroesophageal phases of swallowing?
-involuntary
-bolus passes into esophagus
-esophagus contracts sequentially
-lower esophageal sphincter relaxes to allow bolus into stomach
What is odynophagia?
painful swallowing; commonly associated with severe esophagitis or foreign bodies
What are the causes of oral dysphagia?
-prehension deficits
-difficulty with bolus formation
-loss of tongue function
What are the causes of pharyngeal dysphagia?
-impaired initiation of involuntary passage of food through oropharynx
-structural obstruction
-acquired functional disorder
What causes esophageal dysphagia?
difficulty passing bolus through the esophageal body
What causes gastroesophageal dysphagia?
impaired passage of bolus through lower esophageal sphincter
What are the diagnostic signs of oropharyngeal dysphagia?
-undigested food
-food ejection is immediate
-multiple swallow attempts
-poor ability to drink
What are the diagnostic signs of esophageal dysphagia?
-undigested food
-delayed food ejection
-single swallow attempt
-variable ability to drink
How is dysphagia diagnosed?
-history, physical exam, and signalment
-watch patient ingest food and water
-videofluoroscopic swallow study
What are the treatment options for symptomatically treating dysphagia?
-feeding in an elevated position
-varying consistency of diet
-placing a gastrotomy tube
-treating reflux with acid suppressants and pro-kinetics that tighten the lower esophageal sphincter
What is achalasia?
congenital condition in which the cricopharyngeal muscle fails to open during swallowing
What is asynchrony?
acquired or congenital condition in which there is incoordination between pharyngeal contraction and pharyngeal sphincter relaxation
What is the signalment for cricopharyngeal dysphagia in dogs?
-young dogs
-toy breeds
-cocker/springer spaniels
-miniature dachshunds
-golden retrievers
What are the clinical signs of cricopharyngeal dysphagia?
-repeated swallow attempts
-coughing
-regurgitation immediately after or concurrent with swallowing
How is cricopharyngeal dysphagia diagnosed?
-fluoroscopic swallow study
-examination of pharynx
-thoracic radiographs
What are the characteristics of cricopharyngeal dysphagia treatment?
-permanent treatment is myectomy of cricopharyngeus muscle
-can inject botulism toxin into muscle to see if patient has response prior to surgery; not always indicative of surgical outcome
-bilateral myectomy can lead to severe aerophagia/air in stomach
What are the characteristics of the normal esophageal structure?
-cranial/upper esophageal sphincter consisting of cricopharyngeus muscle
-esophageal body is entirely striated muscle in dogs
-esophageal body is striated muscle in the first 2/3 and smooth muscle in the distal 1/3 in cats
-caudal/lower esophageal sphincter is the gastroesophageal sphincter
-innervation is via the vagus nerve
Why is it important that cats have smooth muscle in their esophagus, but dogs do not?
-prokinetics do not act on striated esophageal muscle, only smooth muscle
-prokinetics will leads to constriction of the lower esophageal sphincter
What is the normal function of the esophagus?
transport ingested liquids and solids from the oral cavity to the stomach via primary and secondary peristaltic waves
What are the characteristics of megaesophagus?
-generalized loss of motor function to the esophagus
-dilation and loss of normal peristaltic motility
-food and fluid accumulate in esophagus
What can lead to congenital megaesophagus?
-primary/idiopathic
-congenital myasthenia gravis
What can lead to acquired megaesophagus?
-primary/idiopathic
-secondary
–myasthenia gravis
-lead toxicity
-addison’s disease
-hypothyroidism
-thymoma
What is the most common cause of megaesophagus in dogs?
primary/idiopathic acquired megaesophagus
What are the clinical signs of megaesophagus?
-regurgitation
-malnutrition
-signs of aspiration pneumonia
How is megaesophagus diagnosed?
-thoracic radiographs
-ruling out/identifying underlying causes
What are the treatment options for megaesophagus?
-upright feeding (bailey chair)
-liquid or semi-liquid gruel diets
-antibiotics to treat secondary aspiration pneumonia
-sildenafil to help relax lower esophageal sphincter
Why are prokinetic drugs contraindicated in megaesophagus patients?
they contract the lower esophageal sphincter and make it even more difficult to get food into the stomach
What is the long-term prognosis of megaesophagus?
poor; most patients will succumb to aspiration pneumonia
What is esophagitis?
inflammation of the esophagus
What are the potential etiologies of esophagitis?
-ingestion of caustic agents; dry medications in cats
-chronic vomiting
-foreign bodies
-reflux esophagitis; especially under GA
What are the clinical signs of esophagitis?
-anorexia and adipsia
-ptyalism/hypersalivation
-regurgitation
-odynophagia/painful swallowing
-weight loss
How is esophagitis diagnosed?
-endoscopy +/- biopsy
-typically based on suspicion
What are the treatment steps for esophagitis?
-removal of underlying cause when possible
-small, frequent feedings of a bland, low-fiber, low-fat diet
-neutralization or inhibition of gastric acid secretion using H2-receptor antagonists and proton-pump inhibitors
-diffusion barrier drugs/sucralfate
-prokinetic to increase tone of lower esophageal sphincter
What is the prognosis of esophagitis?
-good for mild to moderate cases
-can lead to esophageal stricture if severe
What can lead to esophageal obstruction?
-foreign body (intraluminal)
-esophageal stricture (intramural)
-neoplasia (intramural)
-space occupying mass (periesophageal)
-persistent right aortic arch (periesophageal)
What are the characteristics of esophageal foreign bodies?
-emergency condition
-stimulates peristalsis
-can lead to severe ulcerative esophagitis, stricture formation, and/or perforation
-commonly entrapped at thoracic inlet, heart base, and diaphragmatic hiatus
What are the clinical signs of esophageal foreign body?
-anorexia and adipsia
-hypersalivation
-regurgitation
-frequent swallowing movements
-retching/gagging
-extension of the neck
How are esophageal foreign bodies diagnosed?
-survey radiographs
-possible barium swallow study
-endoscopy
What are the treatment options for esophageal foreign bodies?
-removal via endoscopy
-surgery/removal via stomach
What are the potential complications caused by esophageal foreign bodies?
-perforation
-aspiration pneumonia
-stricture formation
-segmental hypomotility
What can cause an esophageal stricture?
-severe esophagitis
-esophageal foreign body
-reflux esophagitis, esp. during GA
-medications
What are the clinical signs of esophageal stricture?
-regurgitation
-weight loss with variable appetite
-retching/gagging
-hypersalivation
How are esophageal strictures diagnosed?
-positive contrast radiography
-endoscopic visualization
How are esophageal strictures treated?
-balloon dilation or bougienage
-liquid diet or gastrotomy feeding tube
What is the most common vascular ring abnormality?
persistent right aortic arch; congenital malformation
How are vascular ring abnormalities diagnosed?
-thoracic radiographs
-CT to confirm
How is persistent right aortic arch treated?
surgical resection of ligamentum arteriosum with vascular repair as needed
What is the prognosis of persistent right aortic arch?
-improvement in 90% of treated patients
-irreversible esophageal damage possible; can cause persistent clinical signs
What are the effects of persistent right aortic arch on the esophagus?
dilation and loss of esophageal motility
