Practical Internal Medicine Megaesophagus Wendy Blount, DVM Nacogdoches, TX.

Practical Internal Medicine

Megaesophagus

Wendy Blount, DVM

Nacogdoches, TX

Megaesophagus

The most common

esophageal disorder

in dogs and cats.

Cats Are Not Little Dogs

Speed of Esophageal Transit• Dog – 75-100 cm/sec• Cat – 1-2 cm/sec

Why??• Striated muscle is faster than smooth

So What??Eating fast causes more vomiting in cats – tube

feeding must be slow

Cats Are Not Little Dogs

Muscle Type• Dog – entirely striated• Cat – cranial 2/3 striated, caudal 1/3 smooth

So What??Cisapride works on smooth muscle

Will work better on cats with megaesophagus when compared to dogs

Megaesophagus - Definition

• Part or all of the esophagus is enlarged.• Food is not properly conducted from the

mouth to the stomach.• Affected pets may not get adequate

nutrition.• Affected pets are at risk for aspiration

pneumonia, which can be life threatening.• It can be part of a more widespread

disease or muscle weakness.

Megaesophagus - Etiology

Generalized Megaesophagus

Entire esophagus is affected

Localized megaesophagus

Usually proximal to obstruction




Esophageal Stricture

Causes• trauma• caustic substance swallowed• doxycycline

(Oreo)


Localized megaesophagusUsually proximal to obstruction

Foreign bodyWhere are they most common?• thoracic inlet• base of the heart

(Dr. Weatherly’s Case)




Parasites

• Spirocerca lupi

Spirocirca lupi



Spirocirca lupi

Who Gets It?

• Dogs

How Do They Get It?

• Eating a beetle

Where else can lesions be?

• Aorta

• Stomach




Vascular Ring Anomaly

• persistent right aortic arch (PRAA)

• ring by left subclavian artery and brachiocephalic trunk




Neoplasia

• Esophageal neoplasia

• Mediastinal mass – which tumors?– Lymphosarcoma– Thymoma




Congenital

• Esophageal diverticulum – where?

• Base of the heart - breed?

• English Bulldog


Two Onsets• Congenital• Acquired

What’s the Difference?

Prognosis• Congenital – guarded• Acquired – short term guarded; long term

potentially good, depending on the cause.


Two Types:

• Megaesophagus alone

• ME as part of a generalized myopathy, neuropathy or junctionopathy

Why Do We Care?

If the underlying cause of weakness is not addressed, the animal will not do well


What is Junctionopathy?

Disease of the myoneural junction

Most Common Junctionopathy

Myasthenia gravis

Who has diagnosed a case of myasthenia gravis?

Generalized Megaesophagus - Alone

The most common esophageal disease in dogs and cats is megaesophagus

Causes – two most common• Idiopathic• Myasthenia gravis

Other Causes• Esophagitis• Congenital

Esophagitis

Generalized Megaesophagus - Alone

Esophagitis

Chronic inflammation can result in ileus

Causes of esophagitis:

• Gastroesophageal reflux

• Hiatal hernia

• Chronic GDV


Myasthenia gravis• Auto-immune disorder• Autoantibodies against Ach receptors

There are four kinds of MG– Congenital– Acquired Focal

• Esophagus, pharynx/larynx, facial nerve

– Acquired Generalized– Acquired Acute Fulminant


There are four kinds of MGWhy do we care??Different Prognoses• Congenital – poor• Acquired Acute Fulminant – dismal• Acquired Focal and Generalized

– Long term potentially good– Most cases of acquired MG resolve within a year– Short term guarded– 50% die of aspiration pneumonia during therapy


ME as part of generalized weakness

Causes:• Congenital myopathy, neuropathy,

junctionopathy• Hypothyroidism• Hypoadrenocorticism• Muscular dystrophy• Dysautonomia – more common in cats



Causes:• Immune mediated disease

– Systemic Lupus Erythematosis– Dermatomyositis– Polymyositis

• Giant axonal neuropathy - GSD• Congenital myasthenia gravis



Causes:

• Hereditary myopathy of Labradors

• Lead toxicity

• Thallium toxicity

• Organophosphate toxicity

Vomiting, Regurgitation, Coughing

Time with respect to eating

Vomiting• Minutes to hours after eating

Regurgitation• Minutes to hours after eating

Coughing & gagging• Not related to eating• But can be precipitated by drinking water


Expulsion Process

Vomiting• Active – abdominal contractions

Regurgitation• More passive• Can be confusing – regurgitation can cause gagging and then

retching, and then vomiting

Coughing & gagging• After coughing• Can be confusing – productive cough can cause gagging and

then retching, and then vomiting


Premonitory signs

Vomiting• Salivation, pacing, licking lips, anxiety

Regurgitation• Salivation, exaggerated swallowing

Coughing & gagging• Elevated respiratory rate


Vomiting Regurgitation CoughingHardly digested to

liquidHardly digested to

liquidWhite and foamy

Smell variable May smell sour and fermented

Not usually foul smelling

Rarely has mucus Often is slimy with mucus

May contain mucus or pus

Digested blood suggests vomiting

Blood is rare May be blood tinged

May contain bile Never bile stained Never bile stained

Clues in the History - ME

Signs of Aspiration PneumoniaCoughingFeverDyspneaCyanosis

Can have coughing without regurgitationCoughing can be due to pressure of enlarged esophagus

on the trachea

SUSPECT MEGAESOPHAGUS IN AN OLDER DOG WHO IS BOTH “VOMITING” AND COUGHING


Weight lossCan be severe

Neurologic deficits – LMN SignsDepressed spinal and cranial nerve reflexesLarge, easily expressed bladderConstipation

Muscular abnormalitiesMuscle atrophy with generalized weaknessMuscle pain with polymyositis


Signs of myasthenia gravisWeakness worsens with exerciseChange in barkingDifficulty eating or swallowingWeak or absent palpebral reflex – fatigues

Signs of hypoadrenocorticismVomiting and diarrhea (especially with blood)Lethargy and weaknessShock if severe


Signs of hypothyroidismObesitySymmetrical alopeciaDry eyePyoderma

Signs of lead toxicityVomiting and diarrheaSeizures, dullness, behavior changes, apparent

blindness


Signs of immune mediated disease

Muscle pain - polymyositis

Joint pain or swelling - polyarthritis

Anemia - IMHA

Thrombocytopenia – ITP

Skin or mucous membrane lesions

Fever

Diagnosis of Megaesophagus

The test that most often diagnoses ME

Radiographs

• Survey rads may be normal

• Survey rads may show a gas filled esophagus

• You may need to do both right and left laterals to see air in the esophagus



Radiographs – Barium Esophagram• Normal esophagram shows lines only



Radiographs – Barium Esophagram• Normal esophagram shows lines only• Barium will pool in the esophagus if ME



Radiographs – Barium Esophagram• Normal esophagram shows lines only• Barium will pool in the esophagus if ME• Can assess wall thickness• May see filling defect of radiolucent foreign

body, ulcer, or mass• Can sometimes see a herringbone pattern in

the distal feline esophagus, due to mucosal folds


The test that most often diagnoses MERadiographs – Barium EsophagramProcedure:• Administer 5-20 ml barium paste, liquid or

barium coated food• Paste gives the best coating, but can be

dangerous if aspirated• If motility problem with good tone, it may take

barium coated food to see abnormalities***WARN OWNER OF DANGER OF THIS

PROCEDURE***



Radiographs – Survey Abdominal

• May see radiopaque foreign body if heavy metal poisoning

• May see a gas filled stomach if generalized GI motility disorder

• May see displaced pylorus of chronic gastric volvulus.



Fluoroscopy• The best way to evaluate mild to moderate

esophageal hypomotility• 5-20 cc liquid barium per bolus first• Then liquid barium mixed with canned food• Then liquid barium coated kibble• Strictures may show no abnormalities with

liquid barium bolus


Minimum database for ME

CBC

General health profile

Electrolytes and venous blood gases

Urinalysis

Fecal flotation and direct wet mount

Thoracic and cervical radiographs


Patterns in Minimum database

CBCAspiration pneumonia• Neutrophilia with left shift• Activated lymphocytes and monocytesImmune mediated disease (rare)• Absolute reticulocute count 300,000• HCT 16%• Spherocytes


Patterns in Minimum Database

SerologyHypothyroidism• Elevated triglycerides• Elevated cholesterolHypoadrenocorticism• Azotemia (elevated BUN, creat, phos)• Hypercalcemia• Hyperkalemia



Fecal Examination

Standard sugar and salt flotation solutions will not give great yields of Spirocerca lupi larvated eggs

Sodium nitrate or direct wet mount is often more sensitive


Tests indicated in every dog and cat with ME

Thyroid panel• Dog – TSH, T4, freeT4• freeT4ED is indicated if T4 is low, to rule out antithyroid

antibodiesACTH stimulation test• **Different protocols for dogs and cats**Myasthenia gravis titer• Comparative Neuromuscular Laboratory, UC-Davis

Getting a positive test result on one of the above should not preclude testing for the others.

A significant number of ME patients have 2 or even all 3 of these problems concurrently


Ancillary tests for ME

Abdominal ultrasoundElectrodiagnostics – EMG, NCVMuscle and nerve biopsy **RISKY**Blood Lead levelOrganophosphate toxicology screenTensilon testANA (rarely helpful)

Treatment of Megaesophagus

Elevated Feedings

THE PRIMARY TREATMENT IF THE ANIMAL IS TO BE FED BY MOUTH

MAKE SURE YOU SPEND ENOUGH TIME WITH THE OWNER TO FULLY EXPLAIN THIS, AS THEIR PET’S LIFE CAN DEPEND ON IT

Treatment of MegaesophagusElevated Feedings• Upper body should be elevated 45-90 degrees.• Hold this position for 10 minutes after eating• Do this also prior to periods of known

prolonged lateral recumbency (sedation, sleeping)

• Small frequent meals (2-4 or more a day)• Avoid feeding for several hours before bedtime• Experiment with food type to determine which

works best for the patient• Lots of how to videos on www.youtube.com • “Bailey Chair”

http://www.youtube.com/


Elevated Feedings

• Upper body should be elevated 45-90 degrees.• Hold this position for 10 minutes after eating• Do this also prior to periods of known

prolonged lateral recumbency (sedation, sleeping)

• Small frequent meals (2-4 or more a day)• Avoid feeding for several hours before bedtime• Experiment with food type to determine which

works best for the patient


Tube Feeding

Temporary gastrostomy • can help stabilize until megaesophagus can be

improved, it the cause is treatable• Often required for 1-3 months• Medications given by tube are more assured of

absorption• NEVER GIVE DOXYCYCLINE BY MOUTH TO

A PATIENT WITH ME• extremely helpful for aspiration pneumonia


Tube Feeding

Permanent gastrostomy • Place a Pezzar tube first• When stoma is well healed, replace with low

profile gastrostomy tube• Medications given by tube long term• Owners have to be vigilant to keep their pets

from taking in food by mouth• If they do take food PO, they need to keep the

pet’s front end elevated for 10 minutes.


Prokinetics

• Metoclopramide and cisapride - empty the stomach faster to minimize GER and regurgitation

• Cisapride – may actually improve esophageal function

– Seems to work more consistently in cats– Response in dogs varies from dramatically

positive to no response


Treat aspiration pneumonia

• Broad spectrum antibiotics – gram negatives, positives and anaerobes

– Long term therapy might be needed for chronic recurring aspiration pneumonia

– Choose 3-4 that work and rotate q6-8 weeks

• IV fluid therapy – overhydration to keep respiratory secretions coming up

• Coupage• + Nebulization• Gastrostomy tube• NPO – including medications


Treat esophagitis – 2 weeks after resolution of clinical signs

• Sucralfate - PO– Do not give within 2 hours of any other PO meds

• Prokinetics• H2 blockers• Proton pump blockers


Immunosuppression – SKEERY!!

• Might be indicated for:– Myasthenia gravis– SLE– Polymyositis

• Only when IM disease has been confirmed, or as a last resort.

• Dangerous for those with aspiration pneumonia

• Some patients with MG can decompensate when immunosuppressed


Immunosuppression – SKEERY!!

• Drugs:– Prednisone

• Start at 0.25 mg/lb/day and gradually increase to immunosuppression if tolerated

– Azathioprine• Start at 0.5 mg/kg PO SID, and then double if tolerated

• Eventually wean down to the lowest effective dose over 2-3 months

• Those who respond to immunosuppression may be able to be weaned off Mestinon

• Use MG titer to know how long to continue therapy– Begin the weaning process when titer negative– Check monthly to make sure not weaning too fast

Megaesophagus - Prognosis

Severe dilation often carries a poor prognosis, no matter the cause

Spirocerca – rarely can be effectively treatedAcquired idiopathic megaesophagus carry a variable

prognosis, depending on:• Use of permanent gastrostomy• Response to cisapride• Tendency to develop aspiration pneumoniaCongenital megaesophagus• Guarded in general• Occasionally a puppy will have resolution at 6-12

monthsAll patients with ME are at risk for sudden death due to

aspiration and respiratory obstruction

Handouts

• PowerPoint Presentation – behind the white tab• Instructions for Adrenal Testing in Dogs and

Cats• Lab Submission Forms

– TAMU GI Lab Endocrine Submission Form– Comparative Neuromuscular Laboratory Submission

Form and submission instructions• Client Drug Handouts

– Azathioprine– Prednisone– Pyridostigmine

• Client Information Handout– Hiatal Hernia– Megaesophagus

Practical Internal Medicine Megaesophagus Wendy Blount, DVM Nacogdoches, TX.

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