Understanding GERD in Dogs

Instructional Guide

Students will explore mechanisms of gastroesophageal reflux disease (GERD) in dogs and the potential treatments. The lesson will be a brief walk through of videos, coloring of images and centered around a hands-on learning activity.

Intended Grade Level

This lesson is designed for students in early to mid elementary school. Students will need a basic understanding of the relative locations of the esophagus and stomach.

This lesson satisfies these K-12 Minnesota State Standards:

Asking questions and defining problems: Standard 1: Students will be able to ask questions about aspects of the phenomena they observe, the conclusions they draw from their models or scientific investigations, each other’s ideas, and the information they read.

Constructing explanations and designing solutions: Standard 1: Students will be able to apply scientific principles and empirical evidence (primary or secondary) to explain the causes of phenomena

Learning objectives

Students will be able to locate the esophagus and stomach in dogs and understand their basic function.

Students will be able to explain the mechanisms of GERD in dogs

Students will be able to explain how a common treatment, acid blockers, work to reduce GERD symptoms.

Lesson Format

This lesson will take no more than 90 minutes total. There are 3 parts to this lesson.

The first is a short video that will help student visualize GERD. This should take about 1 minute to complete. It can be done at the beginning of the lesson or independently at home prior to time in the classroom.

The second activity is a coloring book activity, it will require a printer and some form of coloring supplies such as markers, pencils, or crayons. This is meant to be done independently so each student has a coloring book. This will take approximately 20 minutes. The students will be given the coloring sheets individually and will be making a coloring book showing the anatomy of Chicken Nugget.

The demonstration will take approximately 15 minutes.

Key Information for the Instructor

1. Basic Anatomy and Physiology of the Canine Digestive System

• Esophagus and Stomach:
  • The esophagus is a muscular tube that carries food from the mouth to the stomach. It has a lower esophageal sphincter (LES) at the junction with the stomach, which acts as a barrier to prevent stomach contents from moving back up into the esophagus.
  • The stomach produces gastric acid to help digest food. The lining of the stomach is protected by a mucosal barrier that prevents the acid from damaging the stomach tissue.
  • The LES is crucial in preventing acid reflux. In GERD, this mechanism is compromised.

2. Pathophysiology of GERD in Dogs

• GERD (Gastroesophageal Reflux Disease) occurs when stomach acid and digestive enzymes flow back into the esophagus due to a weakened or relaxed lower esophageal sphincter.
  • Causes of GERD in dogs may include:
    • Gastric emptying disorders (delayed emptying of the stomach, leading to acid reflux)
    • Increased gastric acid production (e.g., due to stress, diet, or certain medications)
  • This reflux of gastric contents irritates and damages the esophageal lining.

3. Symptoms of GERD in Dogs

• Clinical signs of GERD in dogs can include:
  • Regurgitation (the return of undigested food from the stomach into the mouth or esophagus)
  • Vomiting
  • Excessive drooling or salivation

5. Example of Treatment of GERD in Dogs

• Proton Pump Inhibitors (PPIs):
  • Omeprazole is a common PPI used to treat GERD. PPIs work by blocking the proton pumps in the stomach lining that produce gastric acid. This reduces acid secretion and helps to heal the esophagus.

Summary points

• GERD is primarily a problem of acid reflux and that its main treatment is aimed at reducing stomach acid production. This is true in humans and dogs.
• Stopping acid production helps stop the GERD symptoms
• Dogs with GERD signs can be treated; learning the symptoms can be useful for dog owners

Activities

See the student page for coloring book storypages and online activities.

Experiment details

Supplies

• A bottle of “stomach acid” (vinegar; colored with food coloring)
• A bottle of “acid blocker” (canola or similar oil; can be also be colored with food coloring if desired)
• Two empty bottles for the stomach/esophagus model. The bottles should have “neck” appearance that will serve as the esophagus.
• Labels for the bottles
• Baking soda and measuring spoon
• Funnel
• Tray and towels (this can get messy)
• Optional – box of omeprazole or ad for omeprazole; many students will have seen advertisements about Prilosec (R) or similar compounds.

Step 1. Label the bottles, discussing the physiological correlates (stomach, esophagus, stomach acid) and how these contribute to GERD. Fill the empty stomach bottles each about 1/4 full with the vinegar (“stomach acid”).

Step 2. With the bottle on a tray (this will get messy), create the “irritated stomach” by adding a large tablespoon of baking soda to the first “stomach” bottle. The goal is to have the vinegar erupt through the esophagus (neck of the bottle).  Discuss the backwards (upwards) flow of stomach acid.

Step 3. Show how treatment can minimize the flow of stomach acid by preventing the eruption. The bottle of oil will be the acid blocker. Add enough oil to the second bottle to create a 1/2″ -1″ layer of oil on top of the vinegar.  Gently add the tablespoon of baking soda to the bottle (you don’t want to disturb the layers).  The reaction should be substantially decreased.  Discuss how the esophagus stayed “safe”.

Common misconceptions and challenge points

Both regurgitation and vomiting are ways animals (and humans) expel contents from the stomach, but they are distinct processes with different underlying mechanisms.

1. Regurgitation

• Definition: Regurgitation is the passive process of bringing up undigested food or fluid from the esophagus or stomach. It is often unaccompanied by nausea or abdominal effort.
• Mechanism:
  • Esophagus Involvement: The contents usually come from the esophagus, and the process is caused by reflux or delayed gastric emptying.
  • The lower esophageal sphincter (LES), a valve between the esophagus and stomach, fails to properly close, allowing stomach contents (food, liquid, or stomach acid) to flow back into the esophagus. This can happen without any effort from the animal.
• Symptoms in Pets with GERD: Pets with GERD (Gastroesophageal Reflux Disease) often experience regurgitation because the weakened LES or increased abdominal pressure causes stomach acid and undigested food to flow back up into the esophagus.

2. Vomiting

• Definition: Vomiting is an active process that involves nausea and forceful expulsion of stomach contents.
• Mechanism:
  • Gastrointestinal Involvement: Vomiting begins with nausea, which is caused by the brain signaling the stomach to empty. The contents of the stomach are pushed upward through the esophagus, often with the help of abdominal contractions.
• Symptoms in Pets with GERD: Vomiting in pets with GERD often occurs when the stomach acid irritates the esophagus or when the stomach is overfilled. Vomiting is usually accompanied by nausea (e.g., drooling, licking lips, or restlessness) and abdominal effort.

Pets with GERD (Gastroesophageal Reflux Disease) can experience both regurgitation and vomiting because of the following factors:

1. Esophageal Dysfunction

• In GERD, the lower esophageal sphincter (LES), which should act as a one-way valve, is weakened or relaxed. This allows for stomach acid and food to move backward into the esophagus (regurgitation).
• This reflux of stomach contents can irritate the esophageal lining, leading to inflammation and even ulceration. The body may then react with vomiting to expel any irritants or excess acid in the stomach.

2. Delayed Gastric Emptying

• Many pets with GERD have a condition called gastroparesis, where the stomach empties more slowly than normal. This increases the chances of acid reflux because the stomach remains fuller for longer periods, leading to both regurgitation (due to acid rising) and vomiting (due to irritation or overload).
• Vomiting can occur when the stomach becomes too full or when the pet’s body attempts to relieve irritation caused by refluxed material.

3. Acid Overproduction

• GERD often involves increased stomach acid production, which can irritate both the stomach lining and the esophagus.

Summary

• Regurgitation is a passive process where undigested food or liquid moves back up into the esophagus and mouth without effort or nausea. This often occurs in GERD due to acid reflux or esophageal dysfunction.
• Vomiting is an active process that involves nausea, abdominal effort, and the expulsion of partially digested food from the stomach. In pets with GERD, vomiting may occur as a response to acid irritation in the stomach or esophagus.
• Pets with GERD experience both regurgitation and vomiting because of esophageal dysfunction, delayed gastric emptying, and increased stomach acid production. The result is irritation and discomfort in the stomach and esophagus, leading to both passive regurgitation and active vomiting.

As an instructor, it’s important to convey that while these two processes may seem similar, they involve different mechanisms in the body. Understanding the pathophysiology behind each process helps explain why both symptoms can occur in pets with GERD.

Further exploration

From Boston’s Children Hospital

From Kingsdale Animal Hospital

Acid Reflux in Dogs: Understanding the Causes and Treatments

From the Amoeba Sisters

Digestive System

Time Stamps: 2:54-4:37 is most relevant to this section

Other chapters within this textbook may be interesting for students. Consider these link(s):

Twisted tummies

Ew what did I just step in?

Images were created by the authors and are CC for NC use