Large Animal Medicine Dysphagia

Front 1

What are the 5 general mechanisms that cause dysphagia?

Back 1

1) Pain induced
-oral lesions
2) Poor mechanics
-bad teeth
-displaced/ fractured jaw
3) Oronasal communication
-Cleft palate
-pharyngeal paralysis
4) Obstructive
5) Neuromuscular
-pharyngeal paralysis, Megaesophagus, botulism, tick paralysis

Front 2

What are 4 examples of obstructive diseases that result in dysphagia?

Back 2

1) Choke
2) Megesophagus
3) Great vessel anomaly
4) Achalasia: is an esophageal motility disorder involving the smooth muscle layer of the esophagus and the lower esophageal sphincter (LES)

Front 3

All causes of dysphagia place animal at risk for ___________.

Back 3

Aspiration

Front 4

What is the large animal medicine definition of choke?

Back 4

Esophageal intraluminal obstruction

Front 5

What are 3 foreign bodies that most commonly cause choke in horses and sheep?

Back 5

Grains, shavings, pellets
-tends to be smaller things that get impacted

Front 6

What type of foreign bodies most commonly cause choke in cattle and goats? What are some examples?

Back 6

Tend to be boluses that get wedged
-corn cobs, whole fruits or vegetables

Front 7

What are 8 predisposing factors for choke?

Back 7

1) Extreme hunger
2) Greedy eater
3) Competition
4) Exhaustion
5) Sedation
6) Bad teeth
7) Neuromuscular problem
8) Obstructive diseases

Front 8

What are the 4 primary locations where choke occurs in large animals?

Back 8

1) Pharynx
2) Thoracic inlet
3) Base of heart
4) Terminus (where esophagus enters cardia)
*all are points of limited distensibility

Front 9

What are the 2 primary signs of choke in any large animal?

Back 9

1) Pseudoptyalism (with feed)
2) Feed and saliva coming out nose

Front 10

What are the 2 primary signs of choke specific to ruminants?

Back 10

1) Bloat- cannot eructate
2) Depression- dehydration & metabolic acidosis

Front 11

What does the CBC of an animal with choke normally reflect?

Back 11

May reflect Stress or inflammation
-if it does= bad, aspiration

Front 12

What is seen on the chemistry panel of a ruminant that has choke?

Back 12

Na+ and HCO3- loss in ruminants
-dehydration if prolonged

Front 13

What are 5 diagnostics used to diagnose choke?

Back 13

1) Clinical signs
2) Palpation of mass in neck (rare)
3) Inability to pass stomach tube
4) Survey or contrast radiographs (assess lungs at same time)
5) Endoscopy (assess mucosa)

Front 14

What are the 5 methods of treatment used to treat choke? How does each method work?

Back 14

1) Prevent eating & drinking
**try to keep head down
2) Sedation
-relaxes esophagus, lowers head, allows you to work
-xylazine > acepromazine
3) Gentry try to pass stomach tube
-pump water through tube against mass to break it up
4) Cuffed stomach tube
-allows vigorous pumping against mass while preventing aspiration
5) Rumenotomy
-relieve bloat, allow animal to relax & pass obstruction, attempt to retrive mass

Front 15

What are the advantages and disadvantages of using a cuffed stomach tube to treat choke?

Back 15

-Advantages: Preventing reflux, so as you pump it maintains pressure and distends esophagus & hopefully everything breaks up
-Disadvantage: if things don't break up pressure just keeps increasing, expensive, pump can fly off, esophagus can rupture, most vets don't have cuffed stomach tubes

Front 16

What can you do if sedation is not making a ruminant with choke lower its head?

Back 16

General anesthesia can be used to complete relaxation
-not done often
-keep head off table to prevent regurgitation
-Now do everything else we talked about

Front 17

You are called out to a dairy to see a cow with choke. You arrive at the dairy and the cow is bloated and in respiratory distress. What should you do?

Back 17

Trocharization or fistulation of rumen to relieve bloat

Front 18

Should solid masses that cause choke be massaged up or pushed downward?

Back 18

Solid masses are better managed if massaged up for retrieval
-various tools available
-can use snare to retrieve mass (can't do in thorax, too many bends)

Front 19

What are the 2 most life threatening things that develop from choke in cattle?

Back 19

Bloat and aspiration

Front 20

What do we worry about developing secondary to choke that has been in there for a few days?

Back 20

Worry about esophageal ulceration/ erosion

Front 21

What are the 4 things that need to be done after correcting choke?

Back 21

1) Endoscopically assess mucosa
-circumferential ulcers may result in strictures
2) Gradually reintroduce water and softened feeds (wetted hay, brands)
3) NSAIDs and antibiotics may be indicated.
-if pneumonia= antibiotics
4) Fluids and correction of metabolic acidosis (ruminants -NaHCO3) may also be indicated

Front 22

When should an animal that had choke corrected be fasted for a couple of days?

Back 22

-Fast 1 to 3 days w/ mucosal lesions (ulcers, erosions)
- Acute--> right back on feed

Front 23

Is choke or esophageal stricture more common?

Back 23

Esophageal stricture= much more rare

Front 24

What are 2 secondary consequences of choke (after correction)?

Back 24

May lead to recurrent choke or megaesophagus

Front 25

What usually results in the formation of esophageal strictures?

Back 25

Usually form as the result of circumferential ulcers due to choke or esophagitis

Front 26

How long does it usually take esophageal strictures to form after the primary lesion (choke, esophagitis)?

Back 26

4 to 8 weeks from the primary lesion

Front 27

What are 2 methods to diagnosing esophageal strictures?

Back 27

1) Endoscopy
2) Barium swallow

Front 28

What are 3 treatments used for esophageal strictures?

Back 28

1) Soft feeds
2) Bougienage
3) Surgery (mainly horses)

Front 29

What is a bougienage?

Back 29

Increasing the size of balloons to stretch out the esophagus
-in large animals all the ones designed for animals are too small so usually use cuffed stomach tube
-NOT common

Front 30

What 6 cranial nerves are involved with swallowing?

Back 30

V, VII, IX, X, XI, XII

Front 31

What does CN V innervate that is related to swallowing?

Back 31

Masseter muscle
Facial sensation

Front 32

What are 2 clinical signs of CN V damage being related to dysphagia?

Back 32

1) Dropped jaw
2) Facial anesthesia

Front 33

What does CN VII innervate that is related to swallowing? What are some clinical signs that dysphagia could be related to CN VII damage?

Back 33

Muscles of face
-lip, ear, eyelid droop

Front 34

What do cranial nerves IX, X and XI innervate that is related to normal eating in large animals?

Back 34

1) Swallowing
2) Esophageal motility (X only)

Front 35

What are 4 clinical signs that are seen in an animal with dysphagia due to cranial nerve IX, X, or XI damage?

Back 35

1) Cough
2) Aspiration
3) Swallowing difficulty
4) Megaesophagus

Front 36

The swallowing of what animal(s) is/are most greatly affected by cranial nerve VII damage?

Back 36

Horses & camelids: horses and camelids use lips alot for mastication, cattle just use their tongues
-VII doesn't cause much dysphagia

Front 37

What do cranial nerves IX and XII innervate that is important for eating? What are the clinical signs of dysphagia due to cranial nerve IX or XII damage?

Back 37

Tongue
-poor prehension
-limp tongue
-loss of saliva and feed

Front 38

Does unilateral tongue paresis cause a big dysphagia in large animals?

Back 38

Unilateral are silent lesions, bilateral lesions are a big deal --> dypshagia & pseudoptyalism
-horses w/ one side affected bite their tongues, but do ok

Front 39

Why can cranial nerves be damaged by brainstem disease?

Back 39

Because they all start as brainstem nuclei

Front 40

What are 6 examples of brainstem diseases that affect cranial nerves V, VII, IX, X, XI, XII?

Back 40

1) EPM
2) Listeriosis
3) Focal symmetrical encephalomalacia
4) Tumor
5) Abscess
6) Rabies

Front 41

Why is cranial nerve damage more common in the horse than ruminants?

Back 41

The cranial nerves related to mastication all go through the guttural pouch and branches of VII are very superficial and X runs down the neck

Front 42

What are 4 conditions of the equine guttural pouch that could potentially damage CNs V, VII, IX, X, XI, XII?

Back 42

1) Empyema
2) Mycosis
3) Melanoma
4) Temperohyoid osteoarthropathy

Front 43

What type of trauma commonly occurs to CN VII in the horse? Why?

Back 43

Cranial nerves VII are very superficial so can be damaged by halter buckles and blunt trauma

Front 44

What type of trauma commonly occurs to CN X in the horse? Why?

Back 44

X runs down the neck
-trauma, venipuncture, head gates

Front 45

How do you diagnose and treat dysphagia due to cranial nerve damage?

Back 45

Identify affected nerve and likely disease process that affected that nerve.
-perform diagnostics and treatment accordingly

Front 46

What are the 4 layers of the esophagus?

Back 46

1) Outer longitudinal muscle layer
2) Inner circular muscle layer
3) Submucosa
4) Mucosa (squamous)

Front 47

What innervates the esophagus?

Back 47

Vagus nerve (X)

Front 48

What type of muscle makes up the esophagus in ruminants, camelids and horses?

Back 48

Ruminants & camelids: All skeletal muscle
Horses: Skeletal muscle except for a short length of smooth muscle at the terminus in horses

Front 49

Solids are propelled down the esophagus (and also UP in ruminants) by ________.

Back 49

Peristaltic waves

Front 50

At the gastroesophageal junction is the ________.

Back 50

Lower esophageal sphincter
-prevents all back flow in horses, but is less restrictive in cattle

Front 51

What are the consequences of erosions in the esophagus?

Back 51

erosions--> esophagitis---> irritation inhibits peristalsis and **RELAXES lower esophageal sphincter

Front 52

What are 8 causes of erosions in the esophagus of large animals?

Back 52

1) Blister beetle
2) Caustic medication (Bute)
3) Plant toxins
-Rhododendron family
-mainly goats
4) harsh feedstuffs
5) Choke
6) intubation
7) Viral diseases
8) Secondary necrobacillosis

Front 53

What is a cause of erosions in the esophagus specific to horses (compared to other large animals)?

Back 53

Gastro(esophageal) reflux
-have an acidic stomach so reflux is more damaging to esophagus and if bile is included then it's really bad (why gastroduodenal is worse than gastroesophageal reflux)

Front 54

What are 3 clinical signs of erosions in ruminants?

Back 54

1) (Pseudo)ptyalism
2) Reluctance to swallow
-"pained" look
3) Regurgitation/ vomition
*because esophagus is irritated

Front 55

**What is the top differential for a vomiting goat?

Back 55

Ask if have access to Rhododendrons or azaleas

Front 56

What are 4 diagnostic techniques used to diagnose esophageal erosions?

Back 56

1) History of medication/ toxic ingestion
2) Endoscopy
-red streaking or plaques
3) Retrieve fluid from lower esophagus (pH <5.0=gastric reflux)
4) Contrast radiographs may reveal thickening, roughness, delayed emptying

Front 57

Should an animal recovering from erosions be offered food?

Back 57

Can try soft- pelleted feed or no feed to rest esophagus
-total parenteral nutrition if necessary

Front 58

What can you give a horse to increase esophageal contractions, gastric emptying and LES pressure?

Back 58

Metoclopramide (dopamine antagonist) or bethanechol (cholinergic)

Front 59

What is the general cause of megaesophagus?

Back 59

Poor muscular contractility

Front 60

Megaesophagus can be focal or generalized, but why does it tend to become more generalized?

Back 60

Becomes more generalized as the secondary feed accumulation/ choke leads to mechanical trauma in the rest of the segments of the esophagus

Front 61

How common is megaesophagus in large animals? Is it worse in ruminants or horses?

Back 61

Relatively infrequent (most common in camelids)
-clinically worse in ruminants than horses because they must move food in both directions, including against gravity

Front 62

What are the 3 causes/ types of megaesophagus?

Back 62

1) Congenital idiopathic
-often noticed at weaning
-fresian horses- hereditary?
2) Adult- onset idiopathic
3) Acquired

Front 63

What are 3 acquired causes of megaesophagus?

Back 63

1) Chronic obstruction
2) Disruption of nerve supply (vagus)
-neck lesions, trauma, neuro disease
3) myopathy

Front 64

What are some abnormalities that can cause chronic obstruction and lead to megaesophagus? (5)

Back 64

1) Choke
2) Stricture
3) Hiatal hernia
4) Great vessel anomaly (congenital)
5) Achalasia

Front 65

What are some causes of myopathies that can lead to megaesophagus? (7)

Back 65

1) Secondary to erosion
2) Botulism
3) Myasthenia gravis
4) Electrolyte & acid-base abnormalities
5) Sepsis
6) Sarcocystis
7) Warbles

Front 66

What are 6 clinical signs of megaesophagus?

Back 66

1) Ptyalism
2) Bulge or fluid wave in neck
3) Nasal reflux
4) Regurgitation
5) Poor growth or weight loss
6) Signs of choke

Front 67

Why is weight loss more common in ruminants with megaesophagus?

Back 67

Even if a ruminant can swallow, they need to regurgitate to fully break down feed

Front 68

How is a definitive diagnosis of megaesophagus made?

Back 68

Esophagram (barium swallow)-demonstrates dilation and decreased clearance
-can also do manometry which measure the peristaltic pressure in the esophagus

Front 69

If an esophagram cannot be performed, what else can be done to diagnose megaesophagus?

Back 69

-Clinical signs & endoscopy help
-Blood, CSF, etc for underlying disorders

Front 70

What can you do to treat megaesophagus?

Back 70

If possible, cure underlying disorder and it may go away
-congenital idiopathic has a greater chance of spontaneous regression than adult idiopathic

Front 71

What is some conservative treatment that can be done for animals with megaesophagus?

Back 71

-Feed soft feed from a height
-Feed ruminants feeds that do not have to be rechewed
-metoclopramide or bethanechol may help in some cases (not very good usually manage w/ feed)