When your dog is vomiting white foamy mucus and also has diarrhea, it can feel frightening because the symptoms often appear suddenly and escalate quickly.
Vomiting foam usually means the stomach is irritated or empty, while diarrhea signals inflammation deeper in the digestive tract.
We outline the common causes of a dog vomiting white foamy mucus with diarrhea, what you can do at home, and when to seek veterinary help.
Dog Vomiting White Foamy Mucus and Diarrhea: Why It Happens
A dog vomiting white foamy mucus and diarrhea may be experiencing stomach inflammation, infection, parasites, food intolerance, toxins, pancreatitis, or gastrointestinal disease. Because both vomiting and diarrhea lead to rapid dehydration, these symptoms should always be taken seriously.
Dog Vomiting White Foamy Mucus and Diarrhea: Common Causes
Gastroenteritis
Gastroenteritis is one of the most common reasons dogs vomit white foamy mucus while also having diarrhea. When the stomach becomes irritated, it releases mucus and acid, which mix to create the foamy texture. As inflammation spreads into the intestines, stool becomes loose, watery, or mucusy.
This condition can develop from eating something spoiled, sudden food changes, stress, or ingesting irritating substances.
Dogs may vomit repeatedly, sometimes producing only foam once the stomach is empty. Diarrhea often follows because digestion becomes too fast and unregulated.
A dog with gastroenteritis may appear tired, restless, nauseated, or unwilling to eat. The combination of vomiting and diarrhea quickly depletes fluids and electrolytes, making even mild cases dangerous if untreated.
Read more: Dog Coughing up white foamy mucus (Here’s why)
Food Intolerance or Sensitivity
Food intolerances can cause both vomiting foam and diarrhea when the digestive system reacts strongly to an ingredient. Dogs may be sensitive to chicken, beef, dairy, grains, eggs, or certain additives.
When an offending ingredient irritates the stomach, foam appears first as the body tries to expel the irritant. The intestines respond next with inflammation, causing loose stool.
Dogs with food intolerance often show symptoms after eating a particular meal or treat. They may vomit shortly after eating or in the early morning if their stomach becomes irritated overnight.
Long-term sensitivity leads to chronic inflammation, which causes repeated episodes of vomiting white foam paired with diarrhea, gas, or noisy stomach gurgling.
Parasites
Parasites frequently cause vomiting and diarrhea together. Giardia is particularly associated with slimy, mucusy stool and bouts of vomiting white or yellow foam.
Whipworms irritate the large intestine, causing diarrhea that alternates between soft and watery. Roundworms and hookworms can also disrupt digestion enough to trigger vomiting.
Dogs with parasites may lose weight, appear lethargic, or have intermittent symptoms that come and go. Even dogs on preventatives can get parasites from contaminated soil, shared dog parks, puddles, or standing water.
When parasites disrupt the intestinal lining, nutrients are not absorbed well, and the digestive tract becomes inflamed from top to bottom—making vomiting and diarrhea occur simultaneously.
Pancreatitis
Pancreatitis causes the pancreas to become inflamed and release digestive enzymes prematurely. This creates significant abdominal pain, nausea, and vomiting—usually beginning with white foamy mucus as the stomach empties.
As the illness progresses, diarrhea develops because the intestines become overwhelmed by inflammation and improper fat digestion.
Dogs with pancreatitis often hunch, pace, shake, or refuse food. Their abdomen may feel tight or painful to the touch.
Pancreatitis is commonly triggered by fatty foods, dietary indiscretion, toxins, or metabolic conditions.
When both vomiting and diarrhea occur, dehydration happens quickly, making pancreatitis a medical emergency.
Infections
Bacterial infections such as Salmonella, Clostridium, or E. coli can cause sudden vomiting of white foam followed by explosive diarrhea. Viral infections—especially parvovirus in puppies—also trigger these symptoms because they attack the lining of the stomach and intestines directly.
As the digestive tract becomes inflamed, fluid loss increases, stomach contents ferment improperly, and the dog produces foam during vomiting.
Infections often cause additional signs such as fever, lethargy, foul-smelling stool, or drooling.
Parvo begins with white or clear foam vomiting, then progresses to bloody diarrhea—making early symptoms important to catch.
Dietary Indiscretion
Dogs who eat garbage, spoiled food, chemicals, compost, or unfamiliar items often become sick quickly. The stomach becomes irritated first, producing foamy mucus vomiting. The intestines react next with diarrhea as they attempt to expel the irritant.
This cause is extremely common in dogs who counter-surf, raid the trash, or eat questionable items outdoors.
Depending on what was eaten, symptoms can range from mild to severe. Some ingested items cause ongoing vomiting because they continue to irritate the stomach lining.
If the ingestion involved toxins, discarded food, bones, or foreign objects, the illness may escalate rapidly.
Toxins or Poisons
Exposure to toxic substances—like cleaning chemicals, antifreeze, rodent poison, houseplants, or human medications—can cause severe vomiting followed by diarrhea. The body tries to purge the toxin quickly, resulting in repetitive vomiting of white foam and mucus.
Some toxins cause internal bleeding or neurological symptoms as the condition progresses.
Even small amounts of certain toxins can cause severe gastrointestinal reactions within minutes or hours.
Because toxins spread quickly, both vomiting and diarrhea can worsen rapidly and become life-threatening.
Inflammatory Bowel Disease (IBD)
Dogs with chronic IBD often cycle through episodes of vomiting and diarrhea. When the stomach flares, they vomit white or yellow foam. When the intestines flare, diarrhea appears—sometimes watery, sometimes mucusy.
IBD symptoms may improve temporarily, then return suddenly. Dogs may eat some days and refuse food on others.
Some dogs with IBD also lose weight, become sensitive to specific foods, or show low energy during flare-ups.
Because IBD affects both the stomach and intestines, vomiting foam and diarrhea often appear at the same time.
Partial Obstruction
A partially blocked intestine—caused by toys, bones, socks, sticks, or fabric—can cause vomiting that becomes progressively worse. Early vomiting is usually white foam or mucus because the dog cannot move food past the blockage.
Diarrhea sometimes occurs despite the blockage because liquid stool can squeeze past the obstruction.
Dogs may strain, act restless, drool, or show abdominal discomfort. Partial obstructions can quickly become full obstructions and are medical emergencies.
Read more: Dog Vomiting White Foamy Mucus and Blood (Causes explained)
What to Do If Your Dog Is Vomiting White Foamy Mucus and Has Diarrhea
Begin by withholding food for several hours to allow the stomach to rest. Offer small amounts of water or ice chips to prevent dehydration, but do not allow your dog to gulp water, as this may trigger more vomiting.
After the stomach settles, introduce a bland diet such as boiled chicken and rice or a veterinary digestive formula. Feed small, frequent meals instead of large portions—the goal is to rest the digestive tract, not overwhelm it.
Keep your dog in a calm environment and prevent access to grass, toys, trash, or household chemicals.
Do not give human medications, antacids, or over-the-counter drugs, as many worsen vomiting or cause internal bleeding.
Monitor stool and vomit closely for signs of blood, foreign objects, or worsening consistency.
If your dog vomits repeatedly, shows lethargy, refuses water, or develops worsening diarrhea, veterinary evaluation becomes essential.
Vomiting foam and diarrhea together can cause dehydration extremely quickly, especially in puppies, seniors, or smaller breeds.
When to Call or Visit Your Vet
Contact your veterinarian immediately if your dog:
• Vomits foam repeatedly.
• Has diarrhea for more than 12–24 hours.
• Shows blood in vomit or stool.
• Cannot keep water down
• Seems lethargic, weak, or depressed.
• Has a swollen or painful abdomen.
• Has a fever or warm ears
• Refuses food or water entirely.
• Shows signs of dehydration (dry gums, sunken eyes).
• Recently ate garbage, bones, toys, or unknown items.
• Is a puppy, senior dog, or has chronic health issues.
Seek emergency care if:
• Vomiting is nonstop.
• Stool becomes black or tar-like.
• Your dog collapses or appears disoriented.
• Vomiting contains coffee-ground material.
• A foreign object ingestion is suspected.
Vomiting white foam and diarrhea can escalate rapidly and should never be ignored.
Read more: Dog vomiting yellow foamy liquid (What it means)
Key Takeaway
A dog vomiting white foamy mucus and having diarrhea is showing clear signs of stomach and intestinal irritation.
Whether caused by diet, infection, parasites, pancreatitis, toxins, or inflammatory disease, these combined symptoms always require close attention.
By acting quickly and seeking veterinary care when needed, you can help your dog recover safely and comfortably.