Chapter 30 - Esophagus Flashcards
The esophagus of the horse:
● varies between 125 - 200 cm
● varies between 150-225 cm
● consists of dorsal, cervical and abdominal part
● consists of dorsa, thoracic and abdominal part
varies between 125 - 200 cm
As the esophagus courses caudad:
deviates from a position dorsal to the trachea in the cranial third of the neck to the left side of the medial plane in the middle third of the neck
In a small percentage of horses:
esophagus courses to the right side of the median plane
How many layers has the esophagus. Name them.
4 layers, from the outside to the lumen
fibrous layer (tunica adventitia)
muscular layer (tunica muscularis)
submucosal layer (tela submucosa)
mucous membrane ( tunica mucosa)
On surgical incision, the esophageal wall
separates easily into two distinct layers. Name them
The elastic inner layer,
composed of mucosa and submucosa, is freely movable within
the relatively inelastic outer muscular layer and adventitia
The muscular layers of the esophagus are striated from the _______to the base of the heart where they gradually blend into ____________muscle
The muscular layer of the esopahgus are striated from the pharynx to the base of the heart, where they gradually blend into smooth muscle
As the esophagus courses caudad:
● its mucosal layers increase in thickness, whereas the lumen diminishes
● its muscular layers increase in thickness, whereas the lumen increases
● its muscular layers increase in thickness, whereas the lumen diminishes
● its muscular layers increase in thickness, whereas the lumen increases
● its muscular layers increase in thickness, whereas the lumen diminishes
Considering the muscle fiber orientation in the esophagus: At mid-cervical esophagus the bands of muscle form intercrossing__________, in the caudal portion the outer muscle fibers become more ___________oriented, while the inner muscle layer is thicker and more circular
At mid-cervical esophagus the bands of muscle form intercrossing spirals, in the caudal portion the outer muscle fibers become more longitudinally oriented, while the inner muscle layer is thicker and more circular
What is the primary source of arterial supply to the cervical part of the esophagus?
A) Bronchoesophageal arteries
B) Gastric arteries
C) Carotid arteries
D) Mesenteric arteries
C) Carotid arteries
Which arteries supply the thoracic and abdominal esophagus?
B) Bronchoesophageal and gastric arteries
What is the nature of the vascular pattern of the esophagus?
A) Linear and continuous
B) Radial and segmented
C) Arcuate and segmental
D) Circular and unbroken
C) Arcuate and segmental
Why is careful preservation of vessels necessary during esophageal surgery?
C) Because the esophagus lacks generous collateral circulation
Which cranial nerves are involved in the innervation of the esophagus?
A) Eighth and ninth cranial nerves
B) Ninth and tenth cranial nerves
C) Tenth and eleventh cranial nerves
D) Eighth and tenth cranial nerves
B) Ninth and tenth cranial nerves
Besides the cranial nerves, which other structure contributes to the innervation of the esophagus?
A) Parasympathetic ganglia
B) Spinal cord
C) Sympathetic trunk
D) Autonomic plexus
C) Sympathetic trunk
Where are the mesenteric ganglion cells, which contribute to the innervation of the esophagus, located?
A) In the mucosa
B) In the submucosa
C) In the muscularis
D) In the serosa
C) In the muscularis
What symptom often follows attempts at ingestion in a horse with choke?
A) Anorexia
B) Odynophagia (painful swallowing)
C) Weight gain
D) Decreased thirst
B) Odynophagia (painful swallowing)
How soon after swallowing do signs of choke appear with a distal esophagus obstruction?
A) Immediately
B) 1-2 seconds
C) 10-12 seconds
D) 20-25 seconds
C) 10-12 seconds
What is the propagation speed of the equine esophagus in the proximal two-thirds?
A) 2.3 cm/second
B) 4.6 cm/second
C) 7.1 cm/second
D) 9.4 cm/second
D) 9.4 cm/second
Which condition often accompanies long-duration choke cases?
A) Hypertension
B) Hyperactivity
C) Electrolyte imbalances
D) Weight gain
C) Electrolyte imbalances
What complication frequently follows esophageal obstruction in horses?
B) Aspiration pneumonia
What is recommended during the physical examination of a horse with signs of choke to rule out rabies?
A) Immediate sedation
B) Wearing gloves
C) Administering antibiotics
D) Isolating the animal
B) Wearing gloves
What may be indicated by crepitation of a diffuse, firm enlargement in the cervical esophagus?
Loss of integrity of the esophageal wall
What diagnostic procedure can confirm luminal obstruction in a horse with choke?
Passage of a nasogastric tube
What medication is used to sedate a horse with choke during treatment to prevent further aspiration?
Sedation of the animal with xylazine (1.1 mg/kg IV) lowers the horse’s head and prevents further aspiration
What procedure is recommended to relieve an esophageal obstruction caused by feed or bedding?
Gentle lavage with warm water through a nasogastric tube
What should be monitored in any esophageal disease to check for the development of aspiration pneumonia?
Auscultation and diagnostic imaging of the thorax
What is the main advantage of ultrasonographic examination of the cervical esophagus?
It aids in the determination of the etiology of the obstruction.
What can be identified using ultrasonographic examination besides simple impactions?
Extramural masses
What is the purpose of using barium paste (85% wt/vol with water, 120 ml) in an esophagram?
To outline the longitudinal mucosal folds of the undistended esophagus
Why should the patient preferably not be sedated during the administration of barium for an esophagram?
Sedation suppresses the swallowing reflex and reduces the amount of barium available to coat the esophagus.
What does the administration of liquid barium (480 ml) followed by air (480 ml) achieve in esophagographic studies?
It provides a double-contrast study, permitting examination of mucosal folds with the esophagus distended.
Why is negative-contrast radiography less informative for the caudal cervical and thoracic portions of the esophagus?
Because of the superimposition of the air density of the trachea and lungs.
How can negative contrast radiography be used?
In the cranial cervical area, where the esophagus lies dorsal to the trachea, lesions that restrict distention of the esophageal lumen can be demonstrated with negative-contrast radiography - flexible endoscope can be used to localize the lesion and to insufflate the esophagus during radiography. Alternatively, air (480 mL) delivered by dose syringe under pressure through a cuffed nasogastric tube achieves the same results
What complication can arise from the act of swallowing during contrast studies of the esophagus?
False signs of esophageal stricture
B) False signs of esophageal stricture
By administering xylazine (1.1 mg/kg iV) 5 minutes before the procedure
By administering xylazine (1.1 mg/kg iV) 5 minutes before the procedure
Flexible endoscopy
What potential false diagnostic sign can detomidine induce during an esophagogram, and for how long can it persist?
False signs of megaesophagus; for more than 30 minutes
What additional role does esophagoscopy play when radiographic findings are not diagnostic?
It can define the severity and extent of esophageal lesions.
What feature of the endoscope is necessary for good observation of mucosal lesions?
Flexible with irrigation and insufflation capabilities
Why is endoscopic examination best performed with the endoscope fully inserted and then slowly withdrawn?
To make diagnostic observations while insufflating the esophageal lumen
To make diagnostic observations while insufflating the esophageal lumen
Mucosal disease
Why might the cranial aspect of the cervical esophageal sphincter be difficult to examine endoscopically?
The swallowing reflex is repeatedly stimulated, directing the endoscope tip dorsad.
What endoscopic finding usually indicates disease when observing the esophagus?
Inability to insufflate the esophagus and flatten the mucosal folds
What can produce transverse folds in the esophagus during endoscopy?
Moving the endoscope tip toward the stomach
To allow clearer observation of the area of concern
To allow clearer observation of the area of concern
What is the normal appearance of the esophageal mucosa on endoscopic examination?
White to light pink
White to light pink
Normal swallowing
How can the outline of the trachea be observed during esophagoscopy?
By observing the cervical esophagus when insufflated
What is a key diagnostic feature of the cervical esophagus during endoscopy?
Absence of longitudinal mucosal folds
Absence of longitudinal mucosal folds
To facilitate natural swallowing movement
What should be done if the endoscopic appearance of an esophageal obstruction is obscured by saliva?
Remove the saliva by suction through a nasogastric tube
What diagnostic method is routinely used to evaluate esophageal dysfunction in humans?
C) Intraluminal pressure manometry
What have manometric techniques in horses helped to establish?
Reference esophageal pressure profiles
How many functionally distinct regions of the equine esophagus are identified through manometry?
Four
Which region of the equine esophagus is described as “fast”?
Cranial two-thirds of the esophageal body
Which region of the equine esophagus is described as “slow”?
Caudal one-third of the esophageal body
What type of disorders can manometry better define in horses when conventional methods fail?
Physiologic disorders of the esophagus
What specific clinical information has manometry provided regarding esophageal function in horses?
The effect of drugs used to treat esophageal obstruction
The effect of drugs used to treat esophageal obstruction
A) Upper esophageal sphincter, middle esophagus, lower esophageal sphincter, and gastric junction
B) Cranial esophageal sphincter, caudal esophageal sphincter, “fast” region, and “slow” region
C) Cervical esophagus, thoracic esophagus, abdominal esophagus, and esophageal junction
D) Anterior esophagus, posterior esophagus, lateral esophagus, and medial esophagus
B) Cranial esophageal sphincter, caudal esophageal sphincter, “fast” region, and “slow” region
A) Upper esophageal sphincter, middle esophagus, lower esophageal sphincter, and gastric junction
B) Cranial esophageal sphincter, caudal esophageal sphincter, “fast” region, and “slow” region
C) Cervical esophagus, thoracic esophagus, abdominal esophagus, and esophageal junction
D) Anterior esophagus, posterior esophagus, lateral esophagus, and medial esophagus
It provides a more detailed assessment of esophageal pressure profiles.
Which surgical approach is ideal for esophagotomy and resections involving the proximal third of the cervical esophagus?
A) Ventral approach
B) Ventrolateral approach
C) Thoracotomy
D) Ventral cervical approach
d) Ventral cervical approach
For placing a feeding tube in the mid-cervical esophagus, which approach is recommended?
A) Ventral cervical approach
B) Ventral approach
C) Ventral or ventrolateral approach
D) Thoracotomy
C) Ventral or ventrolateral approach
Which approach is necessary to access the distal half of the esophagus?
A) Ventral cervical approach
B) Ventrolateral approach
C) Thoracotomy
D) Dorsal approach
C) Thoracotomy
What is the purpose of passing a nasogastric tube before inducing anesthesia for esophageal surgery?
To facilitate identification of the esophagus during surgery
What is the purpose of passing a nasogastric tube before inducing anesthesia for esophageal surgery?
A) Infection
B) Laryngeal hemiplegia
C) Esophageal stricture
D) Tracheal collapse
B) Laryngeal hemiplegia
During the ventral approach, which muscles are separated along the midline to expose the trachea?
A) Sternocleidomastoid and omohyoid
B) Sternohyoid and sternothyroid
C) Sternothyroid, sternohyoid, and omohyoid
D) Omohyoid and platysma
C) Sternothyroid, sternohyoid, and omohyoid
What advantage does the ventral approach offer in equine esophageal surgery?
A) Shorter recovery time
B) Excellent ventral drainage
C) Easier access to the thoracic esophagus
D) Minimal muscle separation
B) Excellent ventral drainage
Which approach is used to facilitate firm anchorage of a feeding tube to the skin and prevent impingement on the trachea?
A) Ventral cervical approach
B) Ventral approach
C) Ventrolateral approach
D) Thoracotomy
C) Ventrolateral approach
During the ventrolateral approach, which muscle may need to be incised in the caudal cervical area?
A) Omohyoid muscle
B) Sternothyroid muscle
C) Sternohyoid muscle
D) Cutaneous colli muscle
D) Cutaneous colli muscle
What position is the horse placed in for a thoracotomy to approach the thoracic esophagus?
A) Dorsal recumbency
B) Left lateral recumbency
C) Right lateral recumbency
D) Ventral recumbency
C) Right lateral recumbency
For an intrathoracic esophageal stricture, through which intercostal space was the esophagomyotomy performed on a 5-month-old foal?
A) Fourth intercostal space
B) Fifth intercostal space
C) Sixth intercostal space
D) Eighth intercostal space
D) Eighth intercostal space
In the case of an intrathoracic esophageal pulsion diverticulum in a 7-month-old foal, which rib was resected?
A) Fourth rib on the left side
B) Fifth rib on the right side
C) Eighth rib on the left side
D) Ninth rib on the right side
C) Eighth rib on the left side
Which structures must be sharply divided during the approach to the thoracic esophagus?
A) Sternothyroid and sternohyoid muscles
B) Omohyoid and platysma muscles
C) Serratus ventralis and latissimus dorsi muscles
D) Sternocleidomastoid and omohyoid muscles
C) Serratus ventralis and latissimus dorsi muscles
Why might a subperiosteal rib resection not be necessary in foals during thoracic esophageal surgery?
A) Because the ribs are more flexible
B) Due to the smaller size of the esophagus
C) Rib retractors may provide adequate exposure
D) Foals have thinner muscles
C) Rib retractors may provide adequate exposure
What dictates the choice of intercostal space for a thoracotomy to approach the distal half of the esophagus?
B) Location of the lesion and surgical plan
What procedure was performed on a 7-month-old foal to resect an intrathoracic esophageal pulsion diverticulum?
C) Resection of the eighth rib on the left side
Which of the following is essential during the surgical approach to the thoracic esophagus?
B) Positive-pressure ventilation
In foals, what may not be necessary due to adequate exposure provided by rib retractors during thoracic esophageal surgery?
A) Subperiosteal rib resection
B) Division of the latissimus dorsi muscle
C) Positive-pressure ventilation
D) Incision of the cutaneous trunci muscle
A) Subperiosteal rib resection
What is the most common type of obstructive esophageal disease in animals?
A) Perforation by a foreign body
B) Stricture due to mucosal ulceration
C) Impaction with ingesta or bedding
D) Esophageal tumor
C) Impaction with ingesta or bedding
Which treatment method is usually successful in relieving esophageal obstruction?
C) Nasogastric tube passage and gentle warm water lavage
Which drug is noted for its effect on esophageal relaxation in horses?
A) Acepromazine
B) Diazepam
C) Atropine
D) Lidocaine
A) Acepromazine
In refractory cases of esophageal impaction, which procedure may be necessary if gentle lavage is unsuccessful?
C) Muzzling the animal and repeating treatment after 8 to 12 hours
What is a potential complication of simple impaction of the esophagus that may predispose to reobstruction?
B) Fusiform dilation of the esophagus
For how many days is broad-spectrum antimicrobial therapy generally indicated due to the high risk of aspiration pneumonia following choke?
C) 5 to 7 days
What diagnostic tools are mentioned for identifying foreign bodies in the esophagus?
A) MRI and CT scan
B) Blood tests and biopsy
C) Radiography, ultrasonography, and esophagoscopy
D) Endoscopy and biopsy
C) Radiography, ultrasonography, and esophagoscopy
Figure 30-5. Complete obstruction of the esophagus is localized on esophagography after barium paste swallow. This adult horse had an esophageal stricture. Note the prestenotic dilation.
Figure 30-4. Barium paste (120 mL) given orally outlines the normal longitudinal folds of the mucosa in the undistended lumen of the esophagus.
Figure 30-6. Positive-contrast esophagogram (using liquid barium administered under pressure through a nasogastric tube fitted with an inflatable cuff) shows the distended lumen of the normal esophagus. The cuff prevents reflux of barium into the pharynx and aspiration into the trachea.
How do you administer liquid barium?
Liquid barium (72% wt/vol with water, 480 mL) can be administered under pressure by a dose syringe through a cuffed nasogastric tube to prevent reflux into the pharynx (Figure 30-6). 480 mL of LB followed by air 480 mL
Liquid barium demonstrates what?
- strictures and associated prestenotic dilation of the esophagus,
- masses that displace the esophagus
- best definition of mucosal lesions - mucosal ulcers after feed impaction
- Rupture of the esophagus with barium escapind to surrounding soft tissues
How many type of esophagography can be performed?
1.Feeding the horse with barium past (85%wt/vol with water 120 mL) given by mouth = longitudinal mucosal folds of the undistended esopagus = localization of obstruction or any disruption
2. Cuffed nasogastric tube and liquid barium (82% wt/vol with water 480mL) = strictures and prestenotic dilation as masses
3. Double contrast esophagogram (using liquid barium 480 mL followd by bolus of air 480 mL) delivered by dose dyringe under pressure = mucosal folds with the esophagus distended = better for mucosal lesions such as ulcers
Although a diagnosis can often be made without using all three techniques, each demonstrates lesions not seen with the
other two.
Figure 30-9. Barium esophagogram shows false signs of a stricture when barium is administered under pressure and the radiograph is made during swallowing. This swallow artifact can be avoided if xylazine is administered 5 minutes before the study is begun.
Figure 30-8. Negative-contrast esophagogram (using air insufflation introduced through the flexible endoscope) permits visual localization of the lesion with the endoscope and demonstrates a stricture.
The act of swallowing during contrast studies, when the lumen is being distended, produces false signs of esophageal stricture (Figure 30-9) - how can you contourn?
Xylazine (1.1 mg/kg IV) 5 minutes before the barium-under-pressure, double-contrast, or negative-contrast esophagogram, helps eliminate this swallow artifact by decreasing the reflex “secondary swallows”
Why you shouldn’t use detomidine (use xylazine) before the esophagogram?
if detomidine is used, false signs of megaesophagus can persist for more than 30 minutes.
Is the cranial aspect of the cervical esophageal sphincter easily visible?
No, it is difficult to examine because the swallowing reflex is stimulated repeatedly and the larynx directs the endoscope tip dorsad.
What are the 3 surgical approaches to equine esophagus that can be used?
- Ventral cervical approach
- Ventral or ventrolateral approach
- Thoracotomy
Ventral cervical approach is to which situation?
The ventral cervical approach is best used for esophagotomy, esophagomyotomy, and resections involving the proximal third of the cervical esophagus
The ventral or ventrolateral approach is used in which situation?
ventral or ventrolateral approach is recommended for placing a feeding tube in the mid-cervical esophagus (esophagostomy) or for approaching the distal quarter of the cervical esophagus, especially near the thoracic inlet
Figure 30-14. (A) A 10-cm (4-in) incision through the skin and subcutaneous fascia, which is sharply divided using the scalpel. (B) The paired muscles of the sternothyroid, sternohyoid, and omohyoid are separated along the midline to expose the trachea. (C) A baby Balfour retractor placed through the incision allows easy access to the esophagus.
Figure 30-15. Placement of a feeding tube ventral to the jugular vein permits it to lie in a comfortable position on the neck. Note the butterfly tape bandage sutured to the skin to firmly anchor the tube, along with saliva loss around the tube
Figure 30-19. (A) Longitudinal skin incision exposes the carotid artery (left), esophagus (center), and trachea (right). (B) In this longitudinal esophagotomy, a scalpel is used to incise both the outer layer (muscularis and adventitia) and the inner layer (mucosa and submucosa). (C) The esophagotomy is closed with simple-continuous sutures in the inner layer (mucosa and submucosa) and simple-interrupted sutures in the outer layer (muscularis and adventitia).
Figure 30-20. Endoscopic appearance of a longitudinal esophagotomy that healed by first intention 48 days after surgery. One loop of the suture remains in the healed esophagotomy site.
Figure 30-18. Lateral cervical radiograph of horse with esophageal rupture. Note the extensive subcutaneous emphysema.
Figure 30-22. Barium swallow in a horse with a penetrating foreign body (wire) shows swallowed air and barium that has escaped into the periesophageal tissue.
Figure 30-23. (A) Establishment of ventral drainage following esophageal rupture, in which multiple incisions needed to be made to drain food material from the cranial pectoral area.
Figure 30-25. Slurry made of complete pelleted feed is used to meet the nutritional needs of the patient. In some cases, the feeding tube can be placed through the site of rupture into the stomach
Figure 30-26. An esophagostomy tube should remain in place for a minimum of 7 to 10 days to permit granulation tissue to form a true stoma.
Figure 30-29. Positive-pressure esophagogram showing a stricture in a foal. Note the prestenotic dilation. The lesion was resolved by partial resection and anastomosis
Figure 30-31. Positive-contrast esophagogram using liquid barium administered under pressure through a cuffed nasogastric tube shows stricture with prestenotic dilation. The stenosis was subsequently resolved by esophagomyotomy - Strictures more than 60 days old have usually matured to the point where the cicatrix is too firm to yield any conservative therapy and therefore may be classified as chronic
Figure 30-30. Endoscopic appearance of a stricture 30 days after circumferential ulceration.
Figure 30-32. (A) Esophagomyotomy: longitudinal incision of the outer layer of the esophageal wall.
(B) Elevation and separation of the outer (muscularis and adventitia) and inner (mucosa and submucosa) layers of the esophageal wall to complete the esophagomyotomy. (C) The muscularis and adventitia are not sutured.
Figure 30-34. Partial resection and anastomosis. After longitudinal incision of the outer layer (A), the inner layer is resected (B), and when possible, closed transversely using several simple-continuous sutures (C). The outer layer is then closed with interrupted sutures (D).
Figure 30-37. Positive-contrast esophagogram shows a large fistula remaining after removal of the esophagotomy tube. The cuff on the nasogastric tube prevents reflux of barium into the pharynx.
Figure 30-36. Endoscopic appearance of a large esophageal fistula. Smaller fistulas are often difficult to locate endoscopically.
Figure 30-43. (A) A pulsion diverticulum repaired by inversion of the mucosal/submucosal sac with reconstruction of the muscular layer. (B) The edge of the muscular defect should be débrided back to healthy tissue. (C) The sac is inverted, and the edges of the muscularis are apposed with simple-interrupted sutures of 3-0 polypropylene in a manner that avoids undue tension on the closure and prevents stenosis of the esophageal diameter.
Figure 30-44. (A) Double-contrast study of pulsion diverticulum. (B) Exposure of muscular defect at surgery
Figure 30-46. Barium esophagogram shows the classic appearance of an intramural lesion of the esophagus—in this case, an epithelial inclusion cyst. The esophageal lumen is narrowed caudad and is dilated but not filled with barium craniad because the mural mass produces a filling defect.
