Esophagus Flashcards
What is the esophagus composed of ?
- lined by stratified squamous epithelium
- tunica muscularis consists of striated muscle in Ru & Ca
- in Fe, Eq, Sw, & primates, the distal esophagus contains smooth muscle
How do you perform a post-mortem exam of the esophagus?
- open the entire esophagus & examine the mucosa for erosions & ulcers & the muscle for hypertrophy & strictures
What is megaesophagus?
- (esophageal ectasia)
- dilation of the esophagus b/c of insufficient, absent, or uncoordinated peristalsis in the esophagus
What are the clinical signs of megaesophagus?
- recognized clinically by regurgitation after ingestion of solid food
- on xray, the esophagus is dilated anterior to the lesion & retains radiopaque dyes
- animals are thin & may be affected by respiratory distress (aspiration pneumonia)
what would you see on necropsy w/ megaesophagus?
- dilated esophagus
- putrid ingesta are sometimes found in the dilated portions of the esophagus accompanied by esophagitis
- aspiration pneumonia (may be cause of death)
What are the causes of megaesophagus?
- physical obstruction/stenosis
- innervation/denervation disorders
- idiopathic
What are physical obstructions or stenosis that can cause megaesophagus?
- foreign body
- fibrosis of gastric/cardial orifice (ex: chronic gastric ulceration in Sw) -> entire esophagus is affected
- external pressure (tumour, abscess, etc.) -> esophagus cranial to the lesion is affected
- persistence of R aortic arch -> esophagus cranial to the heart affected
- parasitism (Spirocerca lupi)
What are innervation/denervation disorders that can cause megaesophagus?
- myasthenia gravis
- lead poisoning (waterfowl)
- vagal indigestion
What is myasthenia gravis?
- congenital: inherited deficiency in acetylcholine receptors
- acquired: autoimmune disease directed against acetylcholine receptors of the neuromuscular junction
What is a hiatal hernia?
- protrusion of the abdominal esophagus & cardia of the stomach through the diaphragm into the thoracic cavity, it is generally self-reducing
- sometimes a gastroesophageal intussusception occurs
What is an idiopathic muscular hypertrophy of the distal esophagus?
- seen in Eq & Sw, but usually is of no clinical significance
- occasionally may be associated w/ esophageal impaction or gastric cardinal fibrosis
What are infectious causes of esophageal erosions & ulcers in Ru?
- BVD, bovine papular stomatitis, IBR (neonates), FMD, Rinderpest (eradicated)
What are infectious causes of esophageal erosions & ulcers in Fe?
calicivirus
What are non-infectious causes of esophageal erosions & ulcers?
- reflux esophagitis often accompanied by hyperkeratosis (caused by refluxed gastric HCl acid)
- improper use of stomach tubes
- foreign bodies (ex: bones in Ca), caustic chemicals
What is choke?
- choke is a clinical term referring to esophageal obstruction
where does choke most often occur?
anatomic locations in which the esophagus cannot fully expand (dorsal to larynx, cranial to the first rib at the thoracic inlet, base of the heart, diaphragmatic hiatus)
what are the causes of choke?
- ingestion of large foreign bodies (potatoes, apples, bones, corn cobs, or medicaments)
- neoplastic or inflammatory lesions of the esophagus or periesophageal tissues may cause obstruction
what are the clinical consequences of choke?
- formation of strictures (if chronic), starvation, & aspiration pneumonia: a foreign body lodged against the mucosa for longer than 2 days causes circumferential pressure necrosis of the esophageal mucosa (in part due to ischemia due to muscular constriction), which heals w/ fibrosis & causes strictures during healing
Are there any neoplasia’s associated w/ the esophagus?
papillomatosis (bovine papilloma virus)
megaesophagus
megaesophagus due to persistent R aortic arch
Muscular hypertrophy in the distal esophagus of Eq
erosive esophagitis from BVD
acid reflux esophagitis in Sw
esophageal ulceration due to improper stomach tubing of Eq
foreign body w/ esophageal necrosis in Ca
pressure esophageal necrosis due to choke in Eq
esophageal papillomatosis in Bo
