- 1 1. What is the most common clinical sign of an esophageal disorder?
- 2 2. What is the difference between regurgitation and reflux?
- 3 3. List the causes of regurgitation.
- 4 4. What is megaesophagus?
- 5 5. What is the most common complication of megaesophagus?
- 6 6. Does esophageal dilatation on thoracic radiographs confirm an esophageal disorder?
- 7 7. How is esophageal motility evaluated?
- 8 8. What is myasthenia gravis?
- 9 9. What are the most common clinical signs of myasthenia gravis?
- 10 10. What is the test of choice for myasthenia gravis?
- 11 11. What other tests can be used for myasthenia gravis?
- 12 12. Describe the typical profile of a dog with myasthenia gravis.
- 13 13. How is myasthenia gravis treated?
- 14 14. Describe the principles for management of megaesophagus.
- 15 15. What is an alternative means of feeding dogs with megaesophagus?
- 16 16. What is the prognosis for a dog with megaesophagus?
- 17 17. List causes of esophageal stricture in dogs.
- 18 18. How is esophageal stricture diagnosed?
- 19 19. List the treatment options for esophageal stricture and the success rate for each.
- 20 20. What are the most common areas of the esophagus in which foreign bodies lodge?
- 21 21. How do you manage dogs with an esophageal foreign body?
- 22 22. What treatments are available for esophageal reflux?
1. What is the most common clinical sign of an esophageal disorder?
2. What is the difference between regurgitation and reflux?
Regurgitation refers to passive, retrograde movement of ingested material to a level proximal to the upper esophageal sphincter; usually this material has not reached the stomach. In most cases, regurgitation results from abnormal esophageal peristalsis, esophageal obstruction, or asynchronous function of the gastroesophageal junction.
Reflux refers to the movement of gastric and duodenal contents into the esophagus without associated eructation or vomiting.
3. List the causes of regurgitation.
- Myasthenia gravis
- Systemic lupus erythematosus
- Toxicosis (lead, thallium)
2. Esophageal foreign body
• Intraluminal stricture
• Extraluminal stricture due to compression
- Cranial mediastinal mass
- Thoracic hilar lymphadenopathy
5. Neoplasia (primary or metastatic)
6. Granuloma (e.g., Spirocerca lupi)
8. Esophageal diverticula
4. What is megaesophagus?
Megaesophagus is a specific syndrome characterized by a dilated, hypoperistaltic esophagus.
5. What is the most common complication of megaesophagus?
6. Does esophageal dilatation on thoracic radiographs confirm an esophageal disorder?
No. The following conditions often produce transient dilatation of the esophagus:
• Respiratory distress (dyspnea)
7. How is esophageal motility evaluated?
Thoracic radiography initially evaluates for evidence of an esophageal foreign body, esophageal dilatation, or thoracic mass. Ideally a barium esophagogram with fluoroscopy should be performed. It is best to mix food with the barium to observe for decreased contractility.
8. What is myasthenia gravis?
Myasthenia gravis is an immune-mediated disorder, either acquired or congenital (familial), resulting from the action of autoantibodies against nicotinic acetylcholine receptors at the neuro-muscular junctions.
9. What are the most common clinical signs of myasthenia gravis?
• Premature fatigue with exercise
• Spastic pelvic limb gait
• Respiratory distress
• Weakness of facial muscles
• Decreased palpebral reflex
10. What is the test of choice for myasthenia gravis?
Acetylcholine receptor antibody titers (> 0/6 nM/L) in dogs. Antibodies are detectable in 80-90% of dogs with acquired disease.
11. What other tests can be used for myasthenia gravis?
• Edrophonium response test. Edrophonium (0.1-0.2 mg/kg IV) results in dramatic improvement in gait for 1-2 minutes in many but not all animals. Pretreatment with atropine (0.02 mg/kg IV) decreases salivation, defecation, urination, bronchosecretion, and bronchoconstriction. Oxygen and an endotracheal tube should be readily available.
• Ten percent or greater decremental response to the fourth or fifth compound action potential recorded from the interosseous muscle after repetitive stimulation of the tibia or ulnar nerve at 3 Hz.
• Increase in jitter on single-fiber electromyography.
• Intercostal muscle biopsy identifying acetylcholine receptor antibodies at the neuromuscular junction.
12. Describe the typical profile of a dog with myasthenia gravis.
• Breeds most commonly affected: golden retriever, German shepherd
• Bimodal age of onset: 2-4 years and 9-13 years
13. How is myasthenia gravis treated?
1. Anticholinesterase drugs — neostigmine
• Injectable (Prostigmin [Roche]): 0.02 mg/lb IM every 6 hr
• Oral (Mestinon [Roche]): 0.25-0.45 mg/lb every 8-12 hr
14. Describe the principles for management of megaesophagus.
1. Remove the cause if possible.
2. Minimize chances for aspiration of esophageal contents. (Feed the animal in an upright position so that the upper body is elevated to at least 45° above the lower body. Maintain this position for at least 10 minutes after eating and before bedtime.)
3. Maximize nutrient intake to the GI tract (if possible, feed 2-4 times/day).
15. What is an alternative means of feeding dogs with megaesophagus?
16. What is the prognosis for a dog with megaesophagus?
Guarded to poor.
17. List causes of esophageal stricture in dogs.
• Reflux of gastric acid during general anesthesia (on a tilted operating table)
• Ingestion of a strong acid or alkali material
• Thermal burns
• Hairballs (cats)
18. How is esophageal stricture diagnosed?
Esophageal stricture is diagnosed by barium esophagogram and esophageal endoscopy.
19. List the treatment options for esophageal stricture and the success rate for each.
• Surgery (esophagotomy, patch grafting, resection and anastomosis): < 50% success
• Esophageal bougienage: 50-70% success
• Balloon catheter dilatation: > 50-70% success (treatment of choice, ideally done under fluoroscopy)
20. What are the most common areas of the esophagus in which foreign bodies lodge?
• Thoracic inlet
• Hiatus of the diaphragm
• Base of the heart
21. How do you manage dogs with an esophageal foreign body?
Esophageal foreign bodies are considered an emergency. The following steps are recommended:
1. Endoscopic removal of the foreign body is usually successful. Either extract the foreign body or carefully push it into the stomach. If the foreign body is a bone, it is often best to push it into the stomach. Gastrostomy is not usually required for removal of the bone, but serial radiography should be done to ensure digestion or passage of the bone.
2. If esophagoscopy is unsuccessful, surgical removal is required.
3. Assess the esophageal mucosa for hemorrhage, erosions, lacerations, or perforations.
4. Withhold food and water for 24-48 hours, and give crystalloid fluids and parenteral antibiotics.
22. What treatments are available for esophageal reflux?
• Metoclopramide (Reglan) increases gastroesophageal sphincter tone and decreases gastric reflux into the stomach.
• Sucralfate suspension is an aluminum salt that selectively binds to injured gastroesophageal mucosa and acts as an effective barrier against the damaging actions of gastric acid, pepsin, and bile acids associated with reflux esophagitis.