Esophagus

Question 1

Megaesophagus

Answer 1

esophageal ectasia; esophageal dilatation

Question 2

Dysphagia

Answer 2

difficult swallowing

Question 3

Esophageal achalasia

Answer 3

failure of sphincter to relax

Question 4

Achalasia has been demonstrated as a cause of idiopathic megaesphagus in the dog. True or false.

Answer 4

False - it has not been demonstrated as a cause

Question 5

Megaesophagus is more common in ____ than in ___ and has been observed in ____ and adult ____.

Answer 5

more common in dogs than in cats; foals and adult horses

Question 6

What is a common sequela to regurgitation of food?

Answer 6

Aspiration pneumonia

Question 7

Congenital megaesophagus

Answer 7

usually becomes apparent at weaning when solid food is first ingested; delayed maturation of esophageal innervation is believed to be the cause of megaesphoagus in neonatal animals

Question 8

Inherited forms of congenital megaesophagus have been documented in these two dog breeds; and there is an increased incidence of megaesophagus in certain ____ (small/large) breeds of dogs, and ____ cats

Answer 8

fox terrier and miniature schnauzer; large breeds; and siamese cats

Question 9

Acquired megaesophagus

Answer 9

occurs spontaneously in adult dogs; it is speculated that a defect resides in the afferent sensory arm of the vagal nerve reflex, which in turn is required to initiate the efferent or motor arm of esophageal contraction (without sensory reinforcement from an intraluminal food bolus normal coordination esophageal contractions do not occur)

Question 10

In acquired megaesophagus; esophageal defect appears to be ______ rather than ____ in origin.

Answer 10

neurogenic, rather than myogenic in origin

Question 11

Acquired megaesophagus occurs in conjunction with other disease conditions; ______ is the most common cause in dogs.

Answer 11

myasthenia gravis

Question 12

Myasthenia gravis

Answer 12

an autoimmune disease caused by antibodies to the acetylcholine receptor resulting in decreased number of acetylcholine receptors at neuromuscular junctions; there is generalized muscle weakness and megaesphagus

Question 13

Besides myasthenia gravis, other causes that lead to megaesophagus include:

Answer 13

polymyositis, hypothyroidism, congenital myopathy, heavy metal poisoning, peripheral neuropathies, vagal indigestion, esophagitis, recurrent gastric dilation

Question 14

Esophagitis is inflammation of the esophagus caused by:

Answer 14

epitheliotrophic viruses such as BVD in cattle and calicivirus in cats; yeast infections in immunocompromised patients; reflux of gastric contents; and ingestion of caustic chemicals

Question 15

Reflux esophagitis

Answer 15

• Loss of lower esophageal sphincter tone allows prolonged contact of gastric juice with the esophageal mucosa, and subsequent mucosal corrosion by acid pepsin. Ulceration and fibrosis result in stenosis (stricture) and dysphagia

Question 16

Three mechanisms of reflux esophagitis

Answer 16

Sequela to surgery involving general anesthesia; Reflux occurs in the presence of a hiatal hernia; Associated with strictured duodenal ulcers in foals

Question 17

Crop

Answer 17

Outpocketing of the esophagus just anterior to the thoracic inlet in many species of birds.
Holds food until passes to lower digestive tract—No digestion occurs

Question 18

Crop mycosis

Answer 18

any species of bird is susceptible; usually secondary to immunosuppresion, debilitation, moldy feed, prolonged antibioitc use; caused by candidia albicans; causes crop wall to be thickened and mucosal surface covered by tenacious tan-white friable material

Question 19

Esophageal obstruction

Answer 19

May be partial or complete and occurs in the normal or diseased esophagus in the presence of ingested food or foreign bodies

Question 20

Sequelae of esophageal obstruction

Answer 20

bloat (ruminants), esophageal perforation, diverticulum formation, pressure necrosis and stenosis

Question 21

Causes of esophageal obstruction

Answer 21

1. Inflammation - esophagitis with ulceration and stenosis;
2. Vascular rings - such as persistent right aortic arch;
3. Neoplasms - esophageal tumors or tumors of other organs that compress the esophagus;
4. Ingested foreign bodies - common sites for lodged foreign bodies are: over the larynx; at thoracic inlet; over the heart; and just anterior to the diaphragm

Question 22

Muscular hypertrophy of esophagus

Answer 22

cause usually not known; usually not associated with clinical signs; not unusual in horses

Question 23

Parasites of the esophagus - Spirocerca lupi

Answer 23

Large granuloma in supporting tissues of esophagus; opening into lumen for release of larvae; dysphagia; firbrosarcoma; osteosarcoma; aortic aneurysm; carried by dung beetles

Question 24

Parasites of the esophagus - Gongylenema

Answer 24

Ruminants, pigs, horses, primates, rodents;
In mucosa; no clinical importance;
Carried by cockroaches, dung beetles

Question 25

Parasites of the esophagus - Capillaria sp.

Answer 25

In many species of birds; causes unthriftiness if heavy infestation; direct transmission; earthworms or copepods; upper digestive tract and intestine; scrapings, fecal smears, histopath; not prolific egg layers

Question 26

Neoplasia of the esophagus is uncommon. True or false.

Answer 26

True