When your dog has loose stool and excessive gas, it’s hard not to worry — or notice. The smell, stomach gurgling, and constant discomfort can make any dog parent uneasy.
These symptoms usually point to digestive upset, but the underlying causes can range from mild diet issues to more serious gut inflammation.
We outline the common causes of loose stool and gas in dogs, what you can do at home, and when to seek veterinary help.
Dog Loose Stool and Gas: Why It Happens
Loose stool and gas in dogs happen when the digestive process is disrupted, causing poor absorption and fermentation in the intestines. This may result from eating spoiled food, a sudden change in diet, food allergies, intestinal parasites, or bacterial imbalances.
When food isn’t properly digested, it produces excess gas while also irritating the intestinal lining — leading to watery or mushy stool.
While occasional gas is normal, persistent flatulence combined with diarrhea is a sign your dog’s gut health needs attention.
Dog Loose Stool and Gas: Common Causes
Dietary Indiscretion
Dogs are natural scavengers, and sometimes their curiosity gets them into digestive trouble. When your dog eats something spoiled, greasy, or non-edible, their stomach and intestines react quickly.
This condition, often called “garbage gut,” causes inflammation in the gastrointestinal tract. The result? Loose stool, stomach gurgling, and flatulence that can clear a room. You may even notice vomiting, loss of appetite, or lethargy.
The gas develops because the body struggles to break down strange materials, leading to fermentation in the intestines.
Most mild cases resolve within a day or two, but severe or persistent diarrhea after scavenging could mean bacterial infection or obstruction, both of which need veterinary care.
Read more: Dog Loose Stool with No Other Symptoms (What it means)
Sudden Diet Change
A sudden change in your dog’s diet is one of the most common causes of loose stool and gas. Dogs’ digestive systems rely on consistent bacterial balance, and when you switch food brands or formulas abruptly, that balance is disrupted.
The gut bacteria that help digest certain proteins or grains are thrown off, resulting in fermentation, excess gas, and loose stool.
You may hear your dog’s belly rumbling or notice they’re passing more gas than usual after meals.
To prevent this, always transition food gradually over 7–10 days by mixing the new food with the old. If the new diet still causes stomach issues after a slow transition, it might contain ingredients your dog is sensitive to — such as chicken, beef, or wheat.
Read more: Dog Loose Stool and Vomiting (What’s really going on)
Food Intolerances and Sensitivities
Food intolerance is a frequent reason for chronic loose stool and gas in dogs. Unlike true allergies, intolerances occur when your dog’s digestive system can’t properly process certain ingredients.
Common culprits include dairy, soy, corn, and high-fat foods. Even premium dog foods can cause problems if your dog is sensitive to one of the proteins or fillers used.
You might notice soft, smelly stools, loud intestinal noises, and excessive flatulence that worsens after eating.
Over time, these reactions can irritate the intestinal lining, making the stool looser and digestion less efficient.
If you suspect food intolerance, your vet may recommend an elimination diet to pinpoint the trigger. Switching to a limited-ingredient or hydrolyzed protein food often brings relief.
Bacterial Imbalance (Dysbiosis)
Your dog’s gut is home to trillions of bacteria that help digest food and keep the immune system strong. When this balance is disturbed — due to antibiotics, stress, or poor-quality diet — harmful bacteria can overgrow, leading to dysbiosis.
This imbalance results in foul-smelling gas and loose stool that may contain mucus. Dogs with dysbiosis often experience chronic digestive issues, inconsistent appetite, and bloating.
The fermentation of undigested food creates gas buildup, while inflammation in the intestines prevents proper water absorption — causing diarrhea or soft stool.
Probiotics and prebiotic-rich foods can help restore healthy gut flora, but long-term dysbiosis may require veterinary treatment and diet adjustment.
Intestinal Parasites
Parasites such as giardia, hookworms, and whipworms are another leading cause of gas and diarrhea in dogs. These microscopic invaders damage the intestinal lining, disrupting digestion and allowing gas to build up inside the bowels.
Puppies, unvaccinated dogs, or pets that frequent parks and communal areas are especially at risk.
Typical signs include watery or greasy stool, strong odor, bloating, and sometimes visible worms in the feces.
Giardia, in particular, is notorious for producing foul-smelling, soft stool accompanied by persistent flatulence.
Because parasites are highly contagious, your vet will likely perform a fecal test and prescribe deworming medication. Regular parasite prevention can help keep your dog’s gut clear and healthy.
Low-Quality or Hard-to-Digest Food
Not all dog foods are created equal. Low-quality kibble often contains fillers like corn, soy, and artificial additives that are difficult for dogs to digest.
When ingredients pass through the digestive tract without proper breakdown, they ferment — releasing large amounts of gas and water into the intestines. The result is flatulence, loose stool, and an unhappy pup.
Even some high-end foods can cause problems if they have too much fat or fiber for your dog’s specific needs. Large breeds, in particular, tend to develop more gas when fed high-fiber diets.
Choosing a high-quality food with easily digestible proteins, moderate fat, and natural ingredients can make a noticeable difference.
Inflammatory Bowel Disease (IBD)
If your dog’s loose stool and gas have become chronic, inflammatory bowel disease may be to blame. IBD is a condition where the intestines remain inflamed over time, interfering with digestion and absorption.
Dogs with IBD often have alternating bouts of diarrhea and normal stool, excessive gas, loss of appetite, and occasional vomiting. Their stool may appear greasy or contain mucus due to intestinal irritation.
Because the inflammation affects how nutrients are processed, food ferments instead of being digested, creating persistent flatulence.
Managing IBD involves prescription diets, anti-inflammatory medications, and probiotics to stabilize the gut. With consistent management, many dogs live comfortably for years.
Read more: Dog Loose Stool and Drinking Lots of Water (Possible causes)
What to Do If Your Dog Has Loose Stool and Gas
If your dog seems otherwise alert and happy, mild cases of loose stool and gas can often be managed at home.
Start by withholding food for 12 hours to allow the digestive system to rest, but always provide plenty of fresh water. After fasting, reintroduce food slowly using a bland diet such as boiled chicken and white rice. Feed small, frequent meals to minimize gas buildup and ease digestion.
Avoid treats, table scraps, or rich foods while your dog’s stomach is healing. If you recently switched foods, return temporarily to the previous diet until the symptoms settle.
Adding probiotics or plain pumpkin (not pie filling) can also help firm up stool and restore healthy gut bacteria. Gradually resume the regular diet after a few days if stools improve.
If gas remains excessive, it may help to switch to a more digestible, limited-ingredient food. Keep an eye on your dog’s hydration — dehydration from loose stool can set in quickly, especially in smaller breeds.
When to Call or Visit Your Vet
Some cases of loose stool and gas indicate deeper health problems that require professional care.
You should contact your veterinarian if your dog’s symptoms last longer than 48 hours or if they show any of these warning signs:
Blood or black, tar-like stool
Repeated vomiting or refusal to eat
Abdominal bloating or pain
Sudden lethargy or weakness
Signs of dehydration such as dry gums or sunken eyes
If your dog has ongoing digestive issues despite dietary changes, your vet may recommend blood tests, stool analysis, or ultrasound imaging.
Chronic gas and diarrhea can also point to food sensitivities, pancreatic disease, or inflammatory bowel conditions that need specific treatment.
Read more: Dog Loose Stool and Panting (Why it happens)
Key Takeaway
Loose stool and gas in dogs usually signal a temporary digestive upset — often from something they ate or a sudden change in diet. But persistent symptoms may point to food sensitivities, parasites, or chronic gut inflammation.
Start with gentle at-home care, such as a bland diet, probiotics, and hydration. If your dog’s symptoms don’t resolve within a day or two, or if they seem weak or in pain, don’t wait to call your vet.
A balanced diet, consistent feeding routine, and regular parasite prevention go a long way in keeping your dog’s tummy calm — and your home a little less gassy.