Medical Management of Megaesophagus

Flashcards covering the medical management, etiology, prevalence, general management, medications, new therapies, alternative treatments, and complications of Megaesophagus in animals, based on the provided lecture notes.

Megaesophagus

Esophageal dilation with hypoperistalsis, a condition where the esophagus is enlarged and lacks normal muscle contractions.

Pathogenesis of Megaesophagus

Unclear, but possibly an abnormality in the sensory neural pathways of the vagus nerve.

Canine Megaesophagus Prevalence

Considered an uncommon disease but is the most common cause of regurgitation in dogs; litters may have multiple affected individuals.

Feline Megaesophagus Prevalence

Considered a rare disease.

Etiology of Megaesophagus

Can be congenital (in puppies and kittens), idiopathic, or acquired (in older dogs and cats).

Bailey Chair

A device used to provide gravity-assisted movement of food down the esophagus to the stomach during elevated feeding for animals with Megaesophagus.

Lower Esophageal Sphincter (LES) Function

Normally stimulated to open by swallowing and bolus pressures within the esophagus, allowing material to empty into the stomach.

Achalasia-like Syndrome

A condition in dogs with Megaesophagus where coordinated or normal LES opening is absent during upright feedings, diagnosed via videofluoroscopy.

Esophageal Achalasia (in people)

A primary esophageal motility disorder characterized by impaired LES relaxation, abnormal esophageal peristalsis, and resultant dilation, typically due to abnormalities in myenteric innervation.

Food Consistency for Megaesophagus

Trial and error, individual to the patient, aiming for high calories; options include meatballs/canned food, soaked kibble, or slurry/gruel.

Upright Feedings Duration

Start at 30 minutes and gradually decrease; longer times may compact food without clearance. Activity after meals may also benefit some animals.

Percutaneous Endoscopic Gastrostomy (PEG) Tube

A type of feeding tube that can be used for animals with Megaesophagus, sometimes combined with an esophageal feeding tube for suctioning.

Hydration Strategies for Megaesophagus

Free choice water is not recommended; water can be given in food, small amounts before meals, thickened (gelatin/Knox Blocks), ice cubes, elevated, or via subcutaneous fluids.

Elevating the Head (for ME patients)

May help reduce regurgitation, aspiration, excessive saliva accumulation, and risks during anesthetic recovery through options like inflatable e-collars, neck hugs, wedge pillows, or slanted beds.

Canine Esophagus Muscle Structure

Composed of striated muscle throughout its entire length.

Feline Esophagus Muscle Structure

Composed of striated muscle in the proximal 2/3 and smooth muscle in the distal 1/3; the LES contains smooth muscle.

Promotility Drugs (for ME)

Metoclopramide, cisapride, and ranitidine are drugs that work only on smooth muscle, may increase LES tone, and increase gastric emptying rate. Bethanechol is a cholinergic drug that works on smooth muscle. No medications are proven to improve esophageal motility in dogs.

Cisapride (for Feline ME)

Considered possibly the most effective promotility drug for cats due to more cholinergic innervation in the feline esophagus; may work on the distal 1/3 and increase LES tone.

Sildenafil (Viagra) in ME Therapy

A phosphodiesterase-5 inhibitor that relaxes smooth muscle; used for LES dysfunction, as it relaxes the LES for a period. Studies in puppies and adult dogs have shown reduced regurgitation and increased weight gain. Must be delivered to the stomach with an elevated position.

Alternative Treatments for ME

Includes Slippery Elm (anecdotally treats GERD) and Acupuncture (reports suggest it may reduce regurgitation and decrease LES pressures), though published studies are limited.

Esophagitis as a Complication of ME

Can worsen clinical picture and lead to stricture formation; treatment with omeprazole and sucralfate may reduce regurgitation and other signs.

Excessive Saliva Accumulation in ME

Caused by normal swallowing or esophagitis, leading to regurgitation, coughing, gagging, sneezing, and wet breathing sounds. Elevation of the head may help; no effective medication for thinning.

Pneumonia as a Complication of ME

Diagnosed via 3-view thoracic radiographs, +/- airway wash/culture; treated with empirical antibiotics (e.g., Clavamox and/or fluoroquinolone) 1-2 weeks beyond radiographic resolution, and nebulization.