Why is my dog so gassy? What causes dog farts and what helps

A bit of wind is a normal part of digestion. If your dog is farting more than usual, the cause is most often what or how they eat, or how active they are. It's time to see your vet when the wind changes suddenly or comes with other signs, such as diarrhoea, vomiting, or weight loss.

The short answer

• Some wind is normal. Plenty of healthy dogs pass gas regularly.

• The usual causes are swallowed air, food fermenting in the gut, and not enough activity.

• The smell and the amount have different causes. Lots of wind isn't always smelly, and smelly wind isn't always frequent.

• Quick things to try: a slow-feeder bowl, no table scraps, and a gentle walk after meals.

• See your vet if the change is sudden, persistent, or comes with other symptoms.

How much farting is normal?

More than you might think. In a survey of 110 dog owners, 47 said their dog was flatulent. Wind was more common in less active dogs who spent most of their time indoors, and no single food stood out as the cause (Jones et al., 1998).

Wind also varies a lot from one day to the next. When researchers measured dogs' gas directly, the amount changed widely in the same dog over time, and even more between dogs (Collins et al., 2001).

So one smelly evening isn't a pattern. When you change something, give it two to three weeks before deciding whether it's helped.

Why dogs fart: the three main causes

• Swallowed air. Dogs who gulp their food, eat competitively alongside other dogs, or pant heavily take in extra air. Flat-faced (brachycephalic) breeds such as French Bulldogs, Pugs, and Boxers are prone to this (PDSA, 2023).

• Fermentation. Anything that isn't fully digested in the small intestine travels to the large intestine, where gut bacteria break it down and release gas. Some fibres and starches are designed to be fermented, while others reach the large intestine because a dog can't digest them well.

• Low activity. Movement helps keep the gut moving, which may explain why less active dogs seem to be windier.

If you share your home with a flat-faced breed, our French Bulldog nutrition guide has more on feeding them comfortably.

Why do dog farts smell so bad?

Much of the gas a dog passes is fairly odourless. The rotten-egg smell comes mainly from hydrogen sulphide, a gas made when gut bacteria break down sulphur-containing compounds. In one study, how bad the wind smelled tracked closely with how much hydrogen sulphide it contained, and people could detect it at very low levels (Collins et al., 2001).

Protein is a big part of the story. Protein that isn't fully digested earlier on gets fermented in the large intestine, and that produces sulphur compounds. When researchers compared dogs eating an animal protein meal with dogs eating soybean meal, the animal protein diet produced more sulphur-based odour compounds in their stools, while moderate levels of soy didn't increase wind (Yamka et al., 2006).

That doesn't mean meat is the problem. It suggests that how well a protein is digested plays a big part in the smell, and that a change in protein source can change it.

Foods that commonly cause wind

• Table scraps. Rich, fatty, or unfamiliar food is a common trigger.

• Dairy. Many dogs don't digest lactose (the sugar in milk) well. Our guide to whether dogs can have milk explains why.

• Spoiled food. Raids on the bin or food left out too long.

• Sudden diet changes. The gut bacteria need time to adjust to a new food.

• Fermentable fibres and pulses. Peas, lentils, chickpeas, and beans contain carbohydrates that gut bacteria ferment. Some dogs are more sensitive to these than others.

Our own dry recipes include peas and chickpeas within the 20% that isn't meat or fish. Most dogs do well on them, but if you're keeping a wind diary, it's worth knowing they're there.

What helps: a two-week plan

1. Slow down mealtimes. A slow-feeder or puzzle bowl reduces gulped air. Feeding dogs apart can help competitive eaters.

2. Split the daily amount into smaller meals. Weigh the total in grams using the pack's feeding guide, then divide it.

3. Cut out scraps and extras. Including dairy and fatty leftovers.

4. Add a gentle walk after meals. Keep it calm rather than energetic, especially for large, deep-chested dogs.

5. Change one thing at a time. If you switch food, do it gradually over seven to 10 days. Our guide to dog food types includes a step-by-step switching plan.

6. Keep a short diary. Note meals, treats, walks, and how windy your dog is each day. After two to three weeks, patterns are much easier to spot.

Do supplements or treats help?

Some evidence exists, though it's limited. In one study, treats combining activated charcoal, Yucca schidigera (a desert plant extract), and zinc acetate reduced the share of very smelly episodes, but didn't reduce how often the dogs passed wind (Giffard et al., 2001).

Yucca also appears in our Superfood Blend™, but at a different amount and alongside many other ingredients, so we don't claim our recipes reduce wind.

Probiotics (beneficial bacteria) are often suggested, but research on them for wind in dogs is still limited. Speak to your vet before trying any supplement, and don't give your dog human remedies without veterinary advice (PDSA, 2023).

When to see a vet, and when it's an emergency

Usually fine: occasional wind in a dog who is eating, playing, and toileting normally.

Book an appointment if the wind is new or noticeably worse, or comes with:

• diarrhoea or soft stools that don't settle

• vomiting

• weight loss or a poor appetite

• blood or mucus in the stools

• tiredness or a change in behaviour

Your vet will look at possible causes such as worms, inflammation in the bowel, pancreas problems, and food sensitivities (PDSA, 2023).

Act straight away if your dog has a swollen, tight belly, is trying to vomit but bringing nothing up, or seems restless and in pain. These can be signs of bloat, where the stomach fills with gas and may twist. It's an emergency, and large, deep-chested breeds are most at risk.

How diet fits in

If you suspect your dog is reacting to a particular ingredient, a recipe built around one named meat or fish makes it much easier to work out what's going on. Our guide to the best hypoallergenic dog food explains how to choose one, and is grain free better for dogs? covers whether removing grains is likely to help.

Our dry recipes each centre on one named protein, such as Free Run Duck, Free Run Turkey, or Salmon, with 80% Meat and Fish Ingredients cooked using our Low and Slow™ method. Browse our dry recipes and wet recipes, and our guide to the best protein for dogs if you're weighing up a switch.

FAQs

Should I be worried if my dog is farting a lot?

Not usually, if your dog is otherwise eating, playing, and toileting normally. Speak to your vet if the wind is new, persistent, or comes with diarrhoea, vomiting, weight loss, or blood in the stools.

Why is my dog farting so much all of a sudden?

A sudden change usually follows something new, such as a change of food, extra treats, a bin raid, or less exercise than usual. If there's no obvious trigger, or other symptoms appear, check in with your vet.

Why do my dog's farts smell like rotten eggs?

That smell comes from hydrogen sulphide, a gas produced when gut bacteria break down sulphur-containing compounds, often from protein that wasn't fully digested. A change of protein source or a gradual food switch can sometimes make a difference.

What can I give my dog for wind?

Start with changes to how your dog eats, such as a slow-feeder bowl, smaller meals, and no scraps. Some treats and supplements may reduce the smell, but ask your vet before giving anything, and never give human medicines without their advice.

My dog is farting but not pooping. Is that a problem?

A day without a poo isn't usually a concern if your dog is otherwise well. If they're straining, haven't passed a stool for more than a day or two, or seem uncomfortable, contact your vet, and seek help straight away if their belly looks swollen.

Do some breeds fart more than others?

Flat-faced breeds tend to swallow more air, so they're often windier. Individual digestion, diet, and activity levels matter more than breed for most dogs.