A dog’s upset stomach can range from mild digestive issues to serious health conditions that need quick help from a veterinarian. Over the years, I’ve seen dogs with all kinds of stomach problems—sometimes it’s just a day of vomiting or diarrhea, other times it’s underlying diseases in the stomach or intestines. Infectious diseases like bacterial, viral, or parasitic diseases can cause sudden symptoms, while noninfectious disorders such as tumors, bloat, or an obstruction can be life-threatening. Recognizing the signs early—like weight changes, fever, or even internal bleeding—can make all the difference in protecting your pet’s body from further harm.
Some dog stomach issues come from diet, stress, or food sensitivities, while others are linked to more complex conditions. I’ve treated dogs whose symptoms—from discomfort to severe digestive distress—were eased simply by adjusting their food at home, and others that needed surgery to treat dangerous blockages. Keep an eye on signs like sudden loss of appetite, changes in stool, or unusual behavior. Whether the causes are simple or complicated, the right approach—be it rest, diet changes, or veterinary care—can help manage dog diarrhea, vomiting, and other digestive symptoms before they turn into something far worse.
What Causes Dog Stomach Upset?
From my years of caring for pets, I’ve learned that the causes of a dog’s stomach issues can be as simple as eating spoiled food or as complex as long-term digestive tract disorders. The dog’s body works through a finely tuned digestive system, stretching from the mouth to the anus, and any problem along this anatomy can lead to digestive issues like diarrhea, vomiting, tummy pain, or changes in bowel movements. Sometimes, these symptoms point to mild trouble, but other times they’re signs of deeper issues within the digestive organs. Understanding how each part of the system works—and spotting changes early—can make all the difference in keeping your dog healthy and free from ongoing stomach distress.
Canine parvovirus
I’ve seen canine parvovirus more times than I wish, and it’s one viral disease that can turn deadly fast, especially for puppies and unvaccinated adult dogs. This infection is caused by a tough virus that survives for months in contaminated areas and resists most common disinfectants. Certain breeds like Rottweilers, American Pit Bull Terriers, Doberman Pinschers, English Springer Spaniels, and German Shepherds have a higher risk. The virus is transmitted through contact with infected feces or by indirect transmission from objects. Even recovered carriers can shed the infection, making it highly contagious. Once inside the body, the virus enters through the mouth or nose, replicates in the bloodstream, and attacks rapidly dividing cells in the bone marrow and the lining of the small intestine, causing severe intestinal damage.
The clinical signs often develop suddenly—vomiting, bloody diarrhea, extreme abdominal pain, and digestive collapse. Because of the tissue destruction, bacteria can leak into the bloodstream, leading to dangerous secondary infections and shock. In puppies, the virus may also cause heart failure. Without emergency treatment, many affected dogs die within hours. A veterinarian will make a diagnosis using a history review, fecal or blood test, and sometimes identify the strain such as CPV-2c.
If caught early, supportive care is the main treatment—IV fluids, nutrition, and antibiotics for infections—but even with the best care, not all dogs survive. The presence of inapparent cases means the virus can spread silently, so preventing exposure is critical. Keeping vaccinations repeated as advised, avoiding high-risk places like boarding facilities during outbreaks, and reducing stress on the digestive system are key steps to protecting your pet.
Treatment and Control
When dogs are fighting a dangerous virus like parvovirus, the main focus is on supportive care to keep them alive while their body heals. In my experience, quick treatment can make all the difference. Fluids and electrolytes are vital to help a dehydrated dog, especially if vomiting is constant. This may include oral electrolyte solutions with sodium and potassium, or intravenous fluids if they can’t drink on their own. A veterinarian might add prescription medication and antibiotics to prevent secondary bacterial infection. Some severely ill dogs need a feeding tube to support gut function until they recover, which can take about a week.
Once there’s an improvement, nutrition is slowly built back up. A bland diet—like cottage cheese and rice—is often used before normal food is reintroduced. It’s important to follow prescription directions and keep to what’s tolerated to support weight gain and ongoing diet stability. Access to fresh water at all times is critical.
Preventing contamination is just as important as treating the disease. Infected animals need isolation in separate housing with strict use of protective gowns, gloves, and footbaths. The area should be kept clean of feces and organic matter before applying bleach and water or approved commercial products for disinfection. Bowls, toys, clothing, hands, cages, and equipment in kennels, shelters, or hospitals must be disinfected before reuse. Outdoor surfaces need removal of waste before disinfectants are applied. The environment can keep the virus viable for months, so vaccination is key—pups should get their shots at the right age, with a booster every few years based on recommendations. Both vaccinated puppies and adult dogs can still be diagnosed with the virus, but protection greatly reduces risk.
Cancers of the Digestive System
Cancer of the digestive system in dogs can appear in the stomach or along the intestinal tract, and it often affects older animals though it can occur at any age. Certain breeds like Belgian shepherds, boxers, German shepherds, poodles, great danes, and some spaniels have a higher risk. Types such as adenocarcinoma and lymphoma are malignant, aggressive, and can spread to other parts of the body. The cause isn’t always clear, but any gastrointestinal tumor can lead to serious consequences depending on the tumor location and extent. Common signs include vomiting, blood in stool, diarrhea, poor appetite, weight loss, lethargy, constipation, straining to defecate, and abdominal pain. In severe cases, there may be fluid in the abdomen, infection, rupture of the bowel, or gastrointestinal anemia visible in pale gums.
A veterinarian will check the abdomen and may use x-rays, contrast dye, or ultrasound to spot bleeding or growths. A rectal examination, biopsy, or endoscopy can help locate and confirm the tumor, with a microscopic review by a pathologist for diagnosis. Finding colorectal cancers early is critical because spread to other organs reduces the chances of a good outcome.
Treatment usually starts with surgical removal of the tumor if possible, followed by chemotherapy to slow further spread. The survival rate depends on the tumor type, whether organs are involved, and how quickly treatment begins. In my work, I’ve seen early detection save lives, while delays often limit what can be done. Regular checks, especially for high-risk breeds, give dogs the best shot at a longer, healthier life.
Stomach issues
In dogs, stomach issues can begin before food even reaches the intestines, as problems in the esophagus or reduced digestive activity may affect how meals are digested. Normally, the mucous walls of the stomach protect it from acids like hydrochloric acid and enzymes that break down what’s been eaten, but if the lining is damaged or irritated, the stomach releases higher amounts of acid, leading to pain and discomfort. Once food passes into the intestines, bacterial, viral, or parasitic infections can cause further harm. One common condition, gastritis, is the inflammation of the stomach’s lining, which can quickly upset a dog’s overall health and appetite.
Common causes of dog digestive issues related to the stomach can include:
- Consumption of overly acidic, spicy, or fatty foods
- Chronic stress or anxiety, which can lead to ulcers and damage to the stomach lining
- Eating substances not meant to be ingested–such as raw meat, spoiled food, or trash–can lead to stomach inflammation
- Eating substances contaminated by parasites, bacteria, or viruses
Intestinal issues
In dogs, intestinal issues can affect both the large and small intestines, which are connected between the stomach and anus. The small intestine absorbs digested food into the blood, carrying nutrients throughout the body, while the large intestine, including the colon, rectum, and anal canal, forms stool and reclaims water and electrolytes. Problems like gas, bloating, flatulence, colitis (an inflammation of the bowel), obstructions, diarrhea, constipation, and other digestive disorders can cause discomfort and disrupt normal digestion.
Common causes of dog digestive issues related to the intestines can include:
- Exposure to allergens, parasites, bacteria, or viruses
- Food intolerances or sensitivities
- Poorly digested food, or contaminated food
- Foreign objects (non-food substances) becoming stuck within the small or large intestine
- Polyps or tumors that obstruct the movement of stool through the intestines
- Dog diarrhea causes such as illness, food intolerance, and parasites
- Constipation due to a lack of fiber, swollen anal glands, or bowel obstructions
If symptoms in any of these areas of your dog’s digestive system are left untreated, issues can move further down the digestive tract and may also lead to complications related to anal gland health.
Inflammation of the Large Intestine (Colitis)
Colitis is an inflammation of the large intestine (or colon) that affects the bowel and can upset the fluid, electrolyte, and salt balance in a dog’s body. Normally, the intestine helps absorb nutrients and form feces, but when intestinal bacteria, parasites, bacterial or parasitic infections, traumatic injury, kidney-related problems, allergic reactions, immune system disorders, dietary changes, genetic predisposition, or other infectious disease in animals interfere, the colon can become irritated. I’ve seen dogs strain to defecate, pass mucus or blood, and have changes in volume, liquid consistency, frequency, or urgency, often with pain, weight loss, and sometimes vomiting.
Since diseases of the small intestine can also cause similar problems, a veterinarian may need an examination with tests like blood, urine, and fecal samples, plus x-rays, ultrasound, endoscopy, or biopsy to get a clear diagnosis. Treatment often involves adjusting the diet to support the digestive system, using feeding plans high in fiber or avoiding protein sources that may cause an allergic reaction—I’ve had patients do well on proteins like duck, lamb, kangaroo, or venison.
When diarrhea is severe, anti-inflammatory medication, medications to control loose stools, anti-parasitic drugs, or targeted therapies for inflammatory bowel disease may be prescribed. If treatment reveals inherited or congenital disorders, long-term care might be necessary to prevent flare-ups and protect overall health.
Constipation
Constipation is a condition where dogs have difficulty with the elimination of stool, often passing dry, hard feces or none at all. In some animals, this problem can progress to obstipation, where the colon is so packed that the dog cannot defecate without help. I’ve seen cases caused by obstruction in the intestines, constriction from tumors, or neuromuscular issues. Matter like hair, bones, or other material from eating garbage can block the passage, while low water intake, environmental stress, pain, pelvic bone injuries, prostate gland enlargement, swollen lymph nodes, cancer, hypothyroidism, dysautonomia, spinal cord disease, nerve dysfunction, or electrolyte abnormalities can also be triggers.
Sometimes, drugs have a side effect of straining or producing ribbon-like stools with a foul-smelling odor. Dogs may show lethargy, depression, loss of appetite, vomiting, or abdominal discomfort. A veterinarian will often start with a thorough examination, x-rays, and tests to look for foreign objects or other affected areas.
Treatment may involve a high-fiber diet, laxatives, enemas, or manual extraction under anesthesia if the blockage is severe. In some cases, surgery is required for removal of objects when other attempts fail, and medications may be given to prevent recurrence. When longterm cases are linked to structural or functional damage, careful management is needed to protect the dog’s health.
Which Dog Breeds Are Most At Risk for Digestive Issues?
Are some dog breeds prone to stomach upset? Depending on the breed of dog, a sensitive stomach could be to blame for your dog’s upset stomach–and could mean that certain symptoms are harder to ignore. So which dog breeds have the unfortunate distinction of dealing with gut distress?
Signs & Symptoms of Digestive Issues in Dogs
It can be hard to see your furry friend struggling with symptoms of digestive issues. Keeping a record of symptoms and their frequency can help you and your vet form a better treatment plan for your pet. Digestive issues in dogs can arise in a variety of symptoms which can provide you with more insight on the cause of the stomach issue.
These are the symptoms most commonly associated with dog digestive issues:
Symptoms of Digestive Issues in Dogs
- Vomiting.
- Diarrhea, with or without blood or mucus.
- Constipation.
- Increased gas or flatulence.
- A lack of appetite.
- Weight loss.
- Fever.
- Dehydration.
What disease attacks the stomach and intestines?
Inflammatory bowel disease, also called IBD, is an umbrella term for a group of conditions that cause swelling and inflammation of the tissues in the digestive tract. The most common types of IBD include: Ulcerative colitis
What are the problems with the stomach and intestines?
Some common problems include heartburn, cancer, irritable bowel syndrome, and lactose intolerance. Other digestive diseases include: Gallstones, cholecystitis, and cholangitis.
What are the 4 disorders of the digestive system?
Digestive disorders encompass a variety of diseases ranging from mild to severe. Common digestive disorders include gastroesophageal reflux disease, cancer, irritable bowel syndrome, lactose intolerance and hiatal hernia.
How to treat intestinal issues in dogs?
It’s important to always ask a veterinarian before giving anything to your dog for an upset stomach. There are certain medications that can be prescribed to help him feel better. Feeding a bland diet—such as boiled chicken and white rice—can be helpful