Ulcers in Dogs: Causes, Symptoms, & Treatment

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Most people have heard about ulcers occurring in humans, but did you know dogs can develop ulcers too? This is an in depth explanation of what ulcers are, the causes of ulcers in dogs, the symptoms dogs with ulcers exhibit, and standard treatment practices for dogs with ulcers.

What are Ulcers in Dogs?

Ulcers are painful lesions in the stomach lining. They develop when the thick, protective mucosal layer of the stomach lining is damaged and degraded. This layer protects the body from the potentially harmful contaminants in food and from the highly acidic digestive juices required to digest food. When the mucosal barrier is compromised, the digestive acids will begin to eat away at the stomach tissues, leading to the manifestation of lesions in the stomach that we call ulcers.  

Symptoms of Ulcers in Dogs

There are rare cases of dogs with ulcers not showing any symptoms, but most dogs will show the following symptoms over time.

Physical Symptoms

  • Weight loss
  • Fever
  • Vomiting – with or without blood present
  • Tachycardia— Rapid heart rate
  • Melena— dark, tarry stools due to presence of digested blood
  • Diarrhea— loose or excessive stools, with or without blood present
  • Abdominal swelling or pain
  • Mucous in stools
  • Anemia— low red blood cells or hemoglobin
  • Pale gums

Behavioral Symptoms

Causes of Ulcers in Dogs

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There are a variety of toxic substances, infections, and diseases that can lead to the development of stomach ulcers. Accidental poisoning is the most commonly seen origin of stomach ulcers in dogs. Therefore, it is important to be aware of which ingestible toxins around your house can lead to this painful fate and to ensure that these are out of reach from your curiously mouthed dogs.

Ingestible Causes of Ulcers in Dogs

  • Plants and Human Foods that are Toxic – including mushrooms, castor beans, sago palm, spicy foods, mistletoe, Jerusalem Cherry, daffodil, onions, chives, garlic, and oysters.
  • Pesticide Toxicity
  • Rodenticide Toxicity – Mouse and rat poison
  • Insecticide Toxicity – Sprays, bait stations, and spot on flea/tick treatments
  • Chemical Poisons – Ethylene glycol & Phenols
  • Heavy Metal Poisons – Lead, Zinc, Iron, and Arsenic
  • Prescription and Nonprescription Drugs for Humans – Anti-inflammatory medications, pain medications, corticosteroids
  • Prescription Drugs for Dogs – Pain relievers, particularly COX-2 inhibitors (Rimadyl, Deramaxx, Flunixin Meglumine, and Previcox
  • Ingestion of sharp objects

Note: There are many common household items and plants that are poisonous to dogs that you should be cautious of in and around your home. If those are too much reading, here’s a fairly comprehensive list covering the most common of both.

Gastrointestinal Obstructions

A fairly common condition characterized by the partial or complete blocking of ingested nutrients into the body and/or the stomach secretions into and through the intestines. The blockage can be caused by tumors or ingestion of foreign objects.

Gastroesophageal Reflux

Another common condition in dogs, acid reflux is characterized by hyperacidity of the stomach that creates a reverse flow of gastrointestinal fluids into the esophagus. The esophagus is a tube that connects the throat and stomach. The components in the gastrointestinal juices can cause damage to the protective, mucosal lining in the esophagus.

Gastrointestinal Parasites

Many parasites that cause ulcers live by attaching to the stomach or intestinal wall where they feed on a dog’s blood to mature and lay eggs. Your dog can be exposed to these parasites through contaminated soil, water, feces, and food (ie: raw meats). For the most part, adult dogs will show no symptoms of parasites until the dog’s immune system is compromised – allowing the parasites to overpopulate in the stomach.

Parasites that can cause ulcers in dogs include:

  • Hookworms
  • Roundworms
  • Giardia
  • Coccidia
  • Tapeworms
  • Threadworms
  • Cryptosporidium
  • Flukes

Diseases that Affect the Gastrointestinal Tract and Cause Ulcers

Addison’s Disease

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This rare disease is characterized by the reduced secretion of corticosteroids from the adrenal gland, the small gland located near the kidney. The particular corticosteroids affected are mineralocorticoids and glucocorticoids, which are critical to the healthy functioning of the body. Addison’s Disease in dogs is hard to recognize, but easy to treat. Ulceration occurs due to the disease causing changes to hydration, blood supply, stomach acid levels, and the ability to repair the mucosal lining.


Pancreatitis in dogs causes inflammation of the pancreas, which is responsible for producing digestive enzymes. Pancreatic inflammation causes premature activation of digestive enzymes in the pancreas. Typically digestive enzymes are inactive in the pancreas.

Liver Disease

The liver is responsible for a lot of important roles: detoxifying blood, assists in breaking down drugs, metabolizing energy sources, storing important molecules (ie: vitamins and glycogen), producing bile, and manufacturing blood clotting proteins.

Kidney Disease or Failure

The kidney is another vital organ that filters the blood; excretes waste and toxins; regulates water, salts, and acids in the body; and regulates red blood cells. If any damage is done to the kidney, it could result in kidney disease or even kidney failure in dogs.

Infectious Diseases that Cause Ulcers in Dogs

This can include bacterial, fungal, and viral infections that affect the stomach such as gastrointestinal inflammation or increased stomach acid.

  • Bacterias that cause can cause ulcers in dogs include: campylobacter, helicobacter,