A Puppy With a Mega Problem

Instructional Guide

Learners will explore megaesophagus, including different causes, and trying to solve cases on their own.

Intended Grade Level

This lesson is intended for college students. Students should understand basic GI physiology

Learning objectives

• Students will be able to explain megaesophagus and common symptoms.
• Students will be able to describe peristalsis in normal motility versus megaesophagus motility.
• Students will be able to describe the difference between primary and acquired megaesophagus.
• Students will be able to describe common treatments including the Bailey Chair and suggest diagnostics for megaesophagus.

Lesson Format

This can be done in any size group. The materials can be printed and disseminated for the cases. Activites require computer or phone access for online quizzes, eBook material, and personal research.

• First, students will start with a pre-learning check to review their understanding of the GI system.
• Play the PowerPoint for the students, you will stop on slide 2 to allow students to engage in independent research to learn more about megaesophagus. Once they complete this research they will answer a frew short questions about what they found.
• Next, play slides 3 and 4 for students before letting them each pick an envelope and read the blurb to themselves. Have students underline or star information they think is important. Next, students will read their short paragraph to their group and will spend 5 minutes discussing the different owners and whether any of the stories sound similar to the puppy they want to adopt.
• Next, assign one of the following conditions to each of the groups to research further. The four conditions that often have megaesophagus as a disorder: Persistent right aortic arch, Myasthenia gravis, congenital idiopathic megaesophagus, and secondary megaesophagus (links to hypothyroidism, addisons, etc). After reserching, students should answer some brief questions.
• Finish up the PowerPoint.
• Have students take a quiz on the differences between each type of disorder.
• If you want to go above and beyond you may walk through  and see if students are able to problem solve and identify what is the most likely diagnosis.

Lesson Background

Megaesophagus is a condition where the esophagus becomes dilated and loses its normal motility. The esophagus normally uses peristaltic contractions to move food from the mouth to the stomach. In megaesophagus, these contractions are weak, absent, or uncoordinated, so food and liquid accumulate in the esophagus instead of reaching the stomach. The dilated esophagus functions more like a “floppy tube” or reservoir rather than a muscular transport organ. Clinical signs of megaesophagus include regurgitation, weight loss and poor growth, malnutrition, aspiration pneumonia, and/or excessive salivation and “gurgling” sounds in the throat.

Megaesophagus can be congenital (present at birth) or acquired later in life. Congenital causes can be due to a genetic predisposition, vascular ring anomalies which can compress the esophagus (such as persistent right aortic arch), and inherited neuromuscular disorders affecting peristalsis. Acquired causes can be idiopathic, due to neuromuscular disease, endocrine or metabolic disorders, obstructive disease and even toxic causes.

To diagnosis megaesophagus, veterinarians look for history and clinical signs indicative of megeasophagus. Radiographs may be taken, and would show a dilated, air- or fluid- filled esophagus. Veterinarians may also perform a contrast esophagram, or barium swallow, which confirms poor motility and esophageal dilation. Endoscopy may also be performed in order to visualize structural abnormalities. Finally, bloodwork can be run to check for underlying conditions which may be causing megeasophagus.

There is no cure for idiopathic megaesophagus—focus is on symptom management and preventing aspiration pneumonia. Feeding management is one of the most common treatment forms, specifically the use of a “bailey chair” to assist dogs eating in an upright position so that gravity assists passage of the food into the stomach. Dogs should also have frequent small meals instead of large meals. If an underlying condition is found, treatment for that condition is indicated.

Activities

• Pre-learning check: Students will answer two general questions about the GI system, prompting them to evaluate what they already know and create hypothesis about megaesophagus.
• Initial research: Students will be prompted to do their own research into megaesophagus and answer three questions to confirm their research, as well as understanding.
• Case-studies: Students will read real-life commentary of owners with pets who have megaesophagus and choose a condition that involves megaesophagus to research. Students will then answer questions about this condition and will connect back to the lesson’s focus: a dog named Larry who has megaesophagus.
• Optional additional case study: Students will have an opportunity to watch a short video about another megaesophagus case and answer quesitons about their understanding.

Common misconceptions and challenge points

• Students may believe that megaesophagus only occurs in puppies. While congenital cases occur in young dogs, many cases are acquired in adulthood, often secondary to diseases like myasthenia gravis or Addison’s disease.

• Students may believe that nny esophageal enlargement means megaesophagus, however sometimes it’s due to a temporary obstruction or foreign body. True megaesophagus involves loss of motility.

• Students may underestimate how common and dangerous aspiration pneumonia is in these patients—it is often the leading cause of death

Assessment

The students will take a brief quiz to test their knowledge.

Further exploration

Other chapters within this textbook may be interesting for students. Some options can be found linked below:

Constipation Station: Megacolon in Cats

Why DO Pandas eat Bamboo?