L4: Equine Esophageal Disorders

left cervical (60% or >2 ft, 39% in thoracic)

A majority of the equine esophagus is located in the _______________ region

Striated or skeletal

The cranial 2/3 of equine esophagus is _____________ muscle

Smooth

The caudal 1/3 of the equine esophagus is _____________ muscle

1. proximal esophageal sphincter

2. cardiac sphincter

what are the two sphincters of the esophagus

conduit for ingesta from mouth to stomach

what is the function of the esophagus

false; no digestive or absorptive role

T/F: the equine esophagus has a minor digestive or absorptive role

Vagus nerve

What nerve provides motor function to the esophagus?

Serosal layer

What layer is missing from the esophagus that causes surgery/healing post injury more complicated?

1. leakage from anastamosis or perforations

2. tension during swallowing or movement

the lack of serosal layer causes..

Dysphagia due to retention of feed, water or saliva

Clinical signs of esophageal disease are consistent with signs of _______________

1. Increased salivation

2. Nasal discharge (feed, water, saliva, mucopurulent)

3. Cough, regurgitation

4. Pain, anxious

5. Dehydration, anorexia

What are the clinical signs of esophageal disease?

Retention of feed, water or saliva in esophagus

Most signs of esophageal disease are secondary to what?

similar

the signs of dysphagia from esophageal disease are (similar/different) from other causes of dysphagia

nursing foals

esophageal obstruction from feed impaction or other primary esophageal disease is uncommon in which types of horses?

1. neuromuscular dysfunction of the palate or dummy foal

2. cleft palate

3. gastric ulcers

differential diagnoses for esophageal diseases or dysphagia in nursing foals

1. Nasogastric intubation

2. Endoscopy/esophagoscopy

3. Imaging: radiography, ultrasound

4. Oral examination

What diagnostics are used for assessing esophageal disease?

Endoscopy/esophagoscopy

Which diagnostics provide the most information for assessing esophageal diseases?

Endoscopy/esophagoscopy

_________ is essential for complete assessment of esophageal disease lumen and mucosa

1. localize and characterize abnormality

2. evaluate damage and complications

3. guide treatment

how is endoscopy and esophagoscopy used?

Cervical

UItrasound is used to evaluate the __________ esophagus

1. localize the probelm as obstruction, rupture mass etc.

2. evaluate esophageal wall thickness and integrity

3. identify extramural mass

purpose of ultrasound for the cervical esophagus

before

gas foci or gas dilation

survey radiographs should be performed (before/after) contrast studies and use to identify ___ or ___

Contrast esophagram

Radiographic evaluation of motility, complicated obstruction, stricture, diverticula, and masses

1. Positive contrast

2. Negative contrast

3. Double contrast

What types of contrasts can be used for contrast esophagrams?

1. Barium sulfate (liquid or paste)

2. Iodinated contrast

What are examples of positive contrast?

Aspiration

What should you be cautious about when using iodinated contrast for a contrast esophagram?

Negative contrast

Air

Double contrast

Air and barium

Double contrast

Which type of contrast is optimal for mucosal detail?

perforation or aspiration

use caution with contrast when ________ is suspected or when increased risk of _________

Pharyngeal muscles

The proximal esophageal sphincter is formed by ____________

Smooth muscle

The distal esophageal sphincter is comprised of _______________

Primary esophageal obstruction

"Simple choke"; intraluminal obstruction; very common emergency

true

T/F: Primary obstruction can occur in any aged horse

1. Dental problem - older horses

2. Rapid feed ingestion ("wolfing")

3. Sedation/ feeding while sedated

4. recent episode of dysphagia, diverticula, abnormal motility

What are predisposing factors for primary esophageal obstructions?

1. Masses (cervical or mediastinal)

2. Foreign bodies

3. Congenital problems

4. Diverticula

5. Strictures

Secondary esophageal obstructions are less common and typically occur from what?

1. Post pharyngeal

2. Thoracic inlet

3. Base of heart

4. Terminal esophagus

primary obstructions can occur anywhere but are most common at locations of esophageal narrowing, what are they?

1. Bilateral nasal discharge (feed, saliva, +/- mucopurulent)

2. Increased salivation

3. Anxiety, distress, sweating

4. Cough, retching, neck extension

5. Pain

6. Frequent attempts to swallow

7. Focal swelling/edema along neck

What are clinical signs of esophageal obstruction?

1. Sedation and gentle nasogastric intubation

2. Endoscopy (definitive)

What are the initial diagnostics for esophageal obstruction?

Provide NOTHING by mouth until horse is evaluated

If you are worried a horse might have choke based off what an owner describes to you, what should you tell the owner?

true

T/F: Uncomplicated obstructions may resolve without treatment

1. Lower head

2. Reduce anxiety

3. Analgesia

4. Dislodge impaction

What are the treatment goals for esophageal obstructions?

1. Sedation - alpha 2 agonist (xylazine, detomidine)

2. Passage of nasogastric tube +/- gentle lavage

3. Antimicrobials, analgesia (NSAIDs), fluids (if prolonged or complicated)

4. If obstruction does not resolve, consider referral if an option

How do you treat uncomplicated (acute) obstruction?

1. Endoscopy (assess mucosal damage and healing)

2. Continued nasogastric intubation and lavage

3. pharmacologic therapy w/ a-2 and xylazine

4. Supportive care (antimicrobials, NSAIDs, IVF)

5. Surgical correction as last resort

What is involved in management of complicated/prolonged esophageal obstructions?

1. protect airway

2. sedation, head below thoracic inlet

3. general anesthesia is needed in rare cases

when passing a NG tube with complicated obstructions. ..

Esophagotomy

What is considered a last resort for treating complicated/prolonged esophageal obstructions?

1. Dehiscence

2. Laryngeal hemiplegia

3. Other (horners syndrome, chronic esophageal obstruction, aspiration pneumonia)

What are the surgical complications associated with esophagotomy?

1. 2% lidocaine via NG tube about 50 mL

2. Oxytocin

3. Buscopan

What are the pharmacologic treatment options for obstruction?

esophageal spasm

lidocain is use to alleviate __ __

Skeletal

Oxytocin reduces ___________ muscle tone in proximal 2/3

anticholinergic parasympatholytic agent

MOA of bucospan

Smooth

Buscopan causes __________ muscle relaxation

true

T/F: There is mixed to little evidence that pharmacological treatment options are successful

1. Dehydration

2. Electrolyte or acid base abnormalities

3. Aspiration pneumonia

4. Reobstruction

5. mucosal ulceration

(Also: failure to resolve/prolonged, esophageal trauma, esophageal rupture)

What are the most common complications from prolonged or recurrent obstruction?

Alkalosis

Electrolyte loss due to esophageal obstruction leads to metabolic (acidosis or alkalosis)

usually due to mixed bacterial infection that is treated with broad spectrum antimicrobial

aspiration pneumonia/pleuroneumonia as a complication

loss of free water with hyponatremia, hypocholremia, hypokalemia leading to metabolic alkalosis with treatment via IV fluids

fluid/salivary and electrolyte loss as a complication

Duration of obstruction and presence of mucosal damage with greatest risk 24-48 hours post resolution

Acute reobstruction risk increases with what?

24 to 72 hours

To avoid acute reobstruction, reintroduce soft feed gradually ___________ post resolution

true

T/F: It may take up to 3 weeks to return to normal diet when preventing acute reobstruction

1. Severe mucosal injury

2. Impaired motility, dilation

3. Strictures, diverticulum, perforation

4. Esophagitis

What are risks for recurrent obstructions?

1. Dental care (especially for older horses)

2. Diet (hay quality, pre soak feed)

3. Do NOT feed a sedated horse

4. Prevent rapid feed ingestion

How do you prevent esophageal obstruction?

Post obstruction due to pressure necrosis and circumferential ulceration

What is the most common cause for esophageal stricture?

1. History of recurrent obstructions

2. Endoscopy

3. Double contrast esophagram

How do you diagnose esophageal stricture?

Medical management

___________ should always occur first, especially if acute, for treating esophageal stricture

1. Soft diet

2. Antimicrobials

3. NSAIDs

What is involved in medical management of esophageal strictures?

2 months

What is the treatment duration for medical management of esophageal strictures?

1. Balloon dilation

2. Surgical resection and anastomosis

What is included in treatment of chronic strictures or those that do not respond to medical therapy?

false; chronic

T/F: acute strictures have a less favorable prognosis

Cervical

Esophageal perforation typically involves the __________ esophagus

1. Prolonged/severe obstruction

2. Trauma (external - kick, NG intubation, severe obstruction)

What are causes for esophageal perforation?

1. Draining fistula

2. Tissue necrosis

3. Cellulitis

4. Edema

5. SQ emphysema

6. Abscess

What are clinical signs of esophageal perforation?

Grave to poor

The prognosis of esophageal perforation is what?

Primary

A _____________ surgical closure should only be done if an esophageal perforation is acute (<12 h) and no contamination

Secondary

A (primary/secondary) closure for esophageal perforation is most typical due to contamination and/or duration on presentation

1. indwelling feeding tube

2. longterm broad spec antimicrobial

3. addressing extensive salivary/electrolyte loss

4. septicemia and cellulitis common findings

secondary closure of esophageal perforation involve?

Cervical

Esophageal diverticula typically localize to the ____________ esophagus

1. Congenital - Friesian horses

2. Trauma

What are causes for esophageal diverticula?

Recurrent obstruction but can be asymptomatic

Signs of esophageal diverticula are often similar to what?

Contrast radiography (could also do endoscopy but sedation can mask it so it can be hard to diagnose this method)

What is the ideal way to diagnosis esophageal diverticula?

1. Dietary management

2. Surgical repair (of small diverticula rare)

What is the treatment for esophageal diverticula?

Traction and pulsion/hernial

What are the two types of diverticula?

Traction diverticula

A true diverticula of the mid-esophagus that is usually asymptomatic associated with post trauma, rarely feed entrapment

Pulsion diverticula

A hernial diverticula of the esophagus that is associated with feed entrapment and therefore increased risk of obstruction or rupture

traction

ID type of diverticulum

pulsion

ID type of diverticulum

Esophagitis

Inflammation and ulceration to mucosa of esophagus

1. salivary and food buffers

2. peristalsis

3. gastroesophageal/cardiac sphincter

normal esophageal mucosal protection involves...

1. increased salivation or retching

2. inappetence and weight loss if chronic

clinical signs of esophagitis may mimic recurrent obstructions like

Reflux

___________ esophagitis is most common

1. Chemical injury from gastric acid and bile salts (most common)

2. Prolonged intubation

3. Trauma

4. Neoplasia

5. Toxin

What are causes for esophagitis?

1. Gastric emptying or motility disorder (pyloric outflow obstruction)

2. Lower esophageal sphincter dysfunction

3. Severe intestinal ileus

4. Severe equine gastric ulcer syndrome (EGUS)

What are causes for reflux/chemical esophagitis?

1. Full gastroscopy

2. Abdominal ultrasound

3. +/- assessment of motility with contrast radiography

What should you always perform if you identify esophagitis?

address the primary cause if possible

what should you do first when managing a case of esophagitis

1. Sulcralfate

2. Control gastric acidity

3. Bethanechol (prokinetic; if you suspect motility disorder)

4. Dietary management and supportive care

How do you manage esophagitis?

sucralfate

what drug acts as a mucosal protectant

PPIs like omeprazole

H2 antagonists like famotidine

what drugs act to control gastric acidity

Megaesophagus

Chronic dilation and hypomotility of esophagus

Friesian horses

Congenital megaesophagus is common in what breed of horse?

Acquired

(Congenital or acquired) megaesophagus is more common