Practical Internal Medicine Megaesophagus Wendy Blount, DVM Nacogdoches, TX

Cats Are Not Little Dogs Speed of Esophageal Transit Dog – 75-100 cm/sec Cat – 1-2 cm/sec Why?? Striated muscle (dogs) faster than smooth (cats) 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 & metoclopramide work on smooth muscle Will work better on cats with megaesophagus when compared to dogs Bethanecol works on striated muscle

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

Megaesophagus - Etiology Localized megaesophagus Usually proximal to obstruction Esophageal Stricture Causes trauma caustic substance swallowed doxycycline (Oreo) endocopy

Megaesophagus - Etiology Localized megaesophagus Usually proximal to obstruction Esophageal Stricture Causes trauma caustic substance swallowed doxycycline (Oreo)

Megaesophagus - Etiology Localized megaesophagus Usually proximal to obstruction Foreign body Where are they most common? thoracic inlet base of the heart (Dr. Weatherly’s Case)

Megaesophagus - Etiology Localized megaesophagus Usually proximal to obstruction

Megaesophagus - Etiology Localized megaesophagus Usually proximal to obstruction

Megaesophagus - Etiology Localized megaesophagus Usually proximal to obstruction Darr Wilson, DVM Boerne, TX

Megaesophagus - Etiology Localized megaesophagus Usually proximal to obstruction Parasites Spirocerca lupi

Spirocirca lupi Localized megaesophagus Usually proximal to obstruction

Spirocirca lupi Localized megaesophagus Usually proximal to obstruction

Spirocirca lupi Localized megaesophagus Usually proximal to obstruction

Spirocirca lupi Who Gets It? Dogs How Do They Get It? Eating a beetle Where else can lesions be? Aorta Stomach

Megaesophagus - Etiology Localized megaesophagus Usually proximal to obstruction

Megaesophagus - Etiology Localized megaesophagus Usually proximal to obstruction Vascular Ring Anomaly persistent right aortic arch (PRAA) ring by left subclavian artery and brachiocephalic trunk

Megaesophagus - Etiology Localized megaesophagus Usually proximal to obstruction Neoplasia Esophageal neoplasia Mediastinal mass – which tumors? Lymphosarcoma Thymoma

Megaesophagus - Etiology Localized megaesophagus Usually proximal to obstruction Neoplasia Esophageal neoplasia Mediastinal mass – which tumors? Lymphosarcoma Thymoma

Megaesophagus - Etiology Localized megaesophagus Usually proximal to obstruction Congenital Esophageal diverticulum – where? Base of the heart - breed? English Bulldog

Megaesophagus - Etiology Generalized Megaesophagus Generalized Megaesophagus Localized megaesophagus Usually proximal to obstruction

Generalized Megaesophagus Two Onsets Congenital – apparent by 3 months of age Acquired – often geriatric What’s the Difference? Prognosis Congenital – guarded Acquired – short term guarded; long term potentially good or guarded, depending on the cause.

Generalized Megaesophagus Two Types of acquired ME: 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

Generalized Megaesophagus What is Junctionopathy? Disease of the myoneural junction Most Common Junctionopathy Myasthenia gravis Who has diagnosed a case of myasthenia gravis?

Generalized Megaesophagus - Alone Esophagitis The most common esophageal disease in dogs and cats is megaesophagus Causes – two most common Idiopathic Myasthenia gravis Other Causes Esophagitis Congenital

Generalized Megaesophagus - Alone Esophagitis Chronic inflammation can result in ileus Causes of esophagitis: Gastroesophageal reflux Hiatal hernia Chronic GDV

Generalized Megaesophagus 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

Generalized Megaesophagus There are four kinds of MG Why 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

Generalized Megaesophagus ME as part of generalized weakness Causes: Congenital myopathy, neuropathy, junctionopathy Hypothyroidism (? Gaynor et al, 2009) Hypoadrenocorticism Muscular dystrophy Dysautonomia – more common in cats

Generalized Megaesophagus ME as part of generalized weakness Causes: Immune mediated disease Systemic Lupus Erythematosis Dermatomyositis Polymyositis Giant axonal neuropathy - GSD Congenital myasthenia gravis

Generalized Megaesophagus ME as part of generalized weakness Causes: Immune mediated disease Systemic Lupus Erythematosis Dermatomyositis Polymyositis Giant axonal neuropathy - GSD Congenital myasthenia gravis Crystal Bohanon Tyler, TX

Generalized Megaesophagus ME as part of generalized weakness 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 Coughing & gagging Not related to eating But can be precipitated by drinking water

Vomiting, Regurgitation, Coughing 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

Vomiting, Regurgitation, Coughing Premonitory signs Vomiting Salivation, pacing, licking lips, anxiety Regurgitation Salivation, exaggerated swallowing Coughing & gagging Elevated respiratory rate

Vomiting, Regurgitation, Coughing Hardly digested to liquid White 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

Clues in the History - ME Signs of Aspiration Pneumonia Coughing Fever Dyspnea Cyanosis Can have coughing without regurgitation Coughing can be due to pressure of enlarged esophagus on the trachea SUSPECT MEGAESOPHAGUS IN AN OLDER DOG WHO IS BOTH “VOMITING” AND COUGHING

Clues in the History - ME Weight loss Can be severe Neurologic deficits – LMN Signs Depressed spinal and cranial nerve reflexes Large, easily expressed bladder Constipation Muscular abnormalities Muscle atrophy with generalized weakness Muscle pain with polymyositis

Clues in the History - ME Signs of myasthenia gravis Weakness worsens with exercise Change in barking Difficulty eating or swallowing Weak or absent palpebral reflex – fatigues Signs of hypoadrenocorticism Vomiting and diarrhea (especially with blood) Lethargy and weakness Shock if severe

Clues in the History - ME Signs of hypothyroidism Obesity Symmetrical alopecia Dry eye Pyoderma Signs of lead toxicity Vomiting and diarrhea Seizures, dullness, behavior changes, apparent blindness

Clues in the History - ME 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

Diagnosis of Megaesophagus The test that most often diagnoses ME Radiographs – Barium Esophagram Normal esophagram shows lines only

Diagnosis of Megaesophagus The test that most often diagnoses ME Radiographs – Barium Esophagram Normal esophagram shows lines only

Diagnosis of Megaesophagus The test that most often diagnoses ME Radiographs – Barium Esophagram Normal esophagram shows lines only Barium will pool in the esophagus if ME

Diagnosis of Megaesophagus The test that most often diagnoses ME Radiographs – Barium Esophagram Normal esophagram shows lines only Barium will pool in the esophagus if ME

Diagnosis of Megaesophagus The test that most often diagnoses 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

Diagnosis of Megaesophagus The test that most often diagnoses ME Radiographs – Barium Esophagram Procedure: 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***

Diagnosis of Megaesophagus The test that most often diagnoses ME 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.

Diagnosis of Megaesophagus The test that most often diagnoses ME 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

Diagnosis of Megaesophagus EM Williams – Tyler, TX The test that most often diagnoses ME 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

Diagnosis of Megaesophagus Minimum database for ME CBC General health profile Electrolytes and venous blood gases Urinalysis Fecal flotation and direct wet mount Thoracic and cervical radiographs

Diagnosis of Megaesophagus Patterns in Minimum database CBC Aspiration pneumonia Neutrophilia with left shift Activated lymphocytes and monocytes Immune mediated disease (rare) Absolute reticulocute count 300,000 HCT 16% Spherocytes

Diagnosis of Megaesophagus Patterns in Minimum Database Serology Hypothyroidism Elevated triglycerides Elevated cholesterol Hypoadrenocorticism Azotemia (elevated BUN, creat, phos) Hypercalcemia Hyperkalemia

Diagnosis of Megaesophagus Patterns in Minimum Database

Diagnosis of Megaesophagus Patterns in Minimum Database 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

Diagnosis of Megaesophagus 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 antibodies ACTH stimulation test **Different protocols for dogs and cats** (handout) 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

Diagnosis of Megaesophagus Ancillary tests for ME Abdominal ultrasound Electrodiagnostics – EMG, NCV Muscle and nerve biopsy **RISKY** Blood Lead level Organophosphate toxicology screen ANA (rarely helpful) CT/MRI for PRAA **RISKY**

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 Megaesophagus 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 Lots of how to videos on www.youtube.com “Bailey Chair”

Treatment of Megaesophagus 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

Treatment of Megaesophagus 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

Treatment of Megaesophagus 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

Treatment of Megaesophagus

Treatment of Megaesophagus

Treatment of Megaesophagus

Treatment of Megaesophagus

Treatment of Megaesophagus

Treatment of Megaesophagus

Treatment of Megaesophagus

Treatment of Megaesophagus Eve Gerome - Bonham, TX

Treatment of Megaesophagus

Treatment of Megaesophagus

Treatment of Megaesophagus

Treatment of Megaesophagus 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 (suspension OK) extremely helpful for aspiration pneumonia

Treatment of Megaesophagus 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.

Treatment of Megaesophagus 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 Bethanecol

Treatment of Megaesophagus Treat aspiration pneumonia Broad spectrum antibiotics – gram negatives, positives and anaerobes Long term therapy might be needed for chronic recurring aspiration pneumonia IV fluid therapy – overhydration to keep respiratory secretions coming up Coupage + Nebulization Gastrostomy tube NPO – including medications

Treatment of Megaesophagus 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

Treatment of Megaesophagus Treat underlying cause Hypoadrenocorticism Prednisone 0.1 mg/lb/day + DOCP/Flurinef Myasthenia gravis Pyridostigmine 1-3 mg/kg PO BID-TID Hypothyroidism (rarely effective) PRAA – surgery Stricture – balloon or bougie Spiracerca lupi – difficult to treat

Treatment of Megaesophagus 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

Treatment of Megaesophagus 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 median survival 90 days Spirocerca – rarely can be effectively treated Acquired idiopathic megaesophagus carry a variable prognosis, depending on: Use of permanent gastrostomy Response to cisapride Tendency to develop aspiration pneumonia Congenital megaesophagus Guarded in general Occasionally a puppy will have resolution at 6-12 months All 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