Can a Chew Help With My Dog's Farts?

Somebody in the house has started opening windows whenever the dog walks in. Can a chew sort it out?

Partly, and mostly for the smell. There is one small, well-designed study behind the anti-gas chew idea, and it found something narrower than most labels suggest. Diet does more of the heavy lifting.

What makes a fart smell?

Not most of it. VCA explains that most flatus is made of odourless gases, and the smell comes from sulphur-containing gases such as hydrogen sulfide (VCA). Those come from bacteria in the large intestine working on whatever reached them undigested.

One research group built a device that sampled gas from 8 dogs and logged hydrogen sulfide every 20 seconds. Their odour judge could detect flatus once hydrogen sulfide went above 1 part per million, and how bad it smelled tracked closely with the hydrogen sulfide level (Collins et al., American Journal of Veterinary Research, 2001). They also found that flatulence varied a great deal from day to day in the same dog and between dogs. Keep that in mind before judging any product on one evening.

So there are two separate problems: how much gas, and how much of it smells.

What did the chew study find?

The same group then tested three ingredients you will still find on anti-gas treats: activated charcoal, *Yucca schidigera* and zinc acetate (Giffard et al., JAVMA, 2001).

In faecal samples in the lab, each cut hydrogen sulfide production: charcoal by 71%, yucca by 38%, zinc acetate by 58%, and all three together by 86%. They then put all three into an edible treat, fed it to 8 adult dogs 30 minutes after their meal, and measured their flatus for 5 hours.

The results split cleanly:

• Amount: no change. Total gas production and the number and frequency of farts were unaffected by any of the agents.
• Smell: much better. The share of episodes with bad or unbearable odour fell by 86%, with a matching rise in episodes that had no odour or only a slight one.

What it did not show matters too. Eight dogs is a very small group. Each test lasted hours, not weeks. Nor did it test whether these agents are safe to feed every day for months. If you want to try a charcoal product regularly, clear it with your vet first, particularly if your dog takes any medication.

And a chew that carries these ingredients is not automatically the same as the one in the study. Check whether the label states how much of each is inside; without that, you cannot compare.

Can a fibre chew add gas?

Yes, and this is the part a lot of gut-chew marketing leaves out. VCA lists carbohydrates and certain fibres fermented by colonic bacteria as a main source of intestinal gas. Fermentable fibres such as lactulose, psyllium and oat bran are named as common causes of flatulence by Vetwest, a group of Australian veterinary clinics.

Prebiotic fibres work precisely by being fermented. That is the catch. Chicory root fibre and inulin are in that family, so a dog starting on one may pass more gas for a while, and a large amount given all at once, on top of a diet that already sends plenty of undigested material to the colon, is more likely to do it. Our piece on [whether inulin is safe for dogs](/blogs/the-furry-fix/inulin-safety-for-dogs) goes through doses.

What does help with the amount?

The bowl, mostly. Vetwest says the most common cause of excessive gas is a diet change or eating something new or spoiled, and that most chronic cases come from a diet the dog digests poorly.

VCA's suggestions:

• a highly digestible, low-residue food, so less reaches the colon to ferment;
• fibre kept to about 5% of the diet on a dry-matter basis, when gas is the problem;
• avoiding soy protein and sulphur-rich vegetables and legumes (soybean meal and peas are often used in dog food);
• several small meals instead of one or two big ones;
• a walk within 30 minutes of eating to encourage a poo.

Two more points come from the same sources, and both are about how a dog eats rather than what it eats: dogs that gulp their food swallow air along with it, so a slow-feeder bowl or kibble scattered across a mat can take some of the wind out of the evening. Milk, spicy food and high-fat scraps are all on the Vetwest list, which matters in Indian homes where leftovers from the family plate are common.

If you change food, do it over about a week. A sudden switch is itself a classic cause of gas; see [how to switch food without stomach upset](/blogs/the-furry-fix/safe-food-transition-for-dogs).

Our longer guide, [why does my dog fart so much](/blogs/the-furry-fix/excessive-dog-gas-farting-causes), covers causes in more depth.

When to see a vet

Gas alone, in a dog who is otherwise bright and eating, is rarely urgent. Book a visit if:

• it comes with diarrhoea, loose stools or vomiting;
• your dog is losing weight;
• you have sorted the diet and nothing has changed after a few weeks;
• the belly seems sore when touched.

Go immediately if the belly is swollen and tight and your dog is retching without bringing anything up, especially in a large, deep-chested dog. Treat that as an emergency.

Our checklist on [when to see a vet](/blogs/news/when-to-take-dog-to-vet-digestive-problems) covers the other digestive red flags.

Where ChewCheer fits

Honestly, not as a gas remedy. ChewCheer is a daily soft chew with chicory root fibre and inulin. It contains no charcoal, yucca or zinc acetate, so the 2001 study tells you nothing about it. Those prebiotic fibres are fermented in the gut, which means some dogs pass more wind in the first days, not less.

If your dog already has a lot of gas, sort the diet first and leave new chews, ours included, until things settle. It also contains chicken, which matters if chicken is a suspected trigger.

The short version

A chew can change the smell more easily than the amount. The most-cited trial, in 8 dogs, found charcoal, yucca and zinc acetate cut bad-smelling episodes by 86% without reducing the number of farts; it was small and short, and long-term safety was not tested. Fibre and prebiotic chews can add gas. For less gas overall, look at the food: digestible, low in soy and legumes, smaller meals, eaten slowly, changed gradually. See a vet if gas comes with diarrhoea, vomiting, weight loss or a swollen belly.

Frequently asked questions

Do anti-gas chews for dogs work?

Some can reduce the smell. The one controlled trial most often cited, in 8 dogs, found a treat with activated charcoal, yucca and zinc acetate cut episodes with bad or unbearable odour by 86%, but did not reduce the amount of gas or the number of farts. It was small and short, and did not test long-term safety.

Why do dog farts smell so bad?

Most of the gas has no smell at all. VCA explains that the odour comes from sulphur-containing gases, mainly hydrogen sulfide, produced by bacteria in the large intestine. Researchers measuring dog flatus found that how bad it smelled tracked closely with its hydrogen sulfide level.

Can a prebiotic or fibre chew make my dog fart more?

It can, especially at first. Prebiotic fibres such as chicory root fibre and inulin are meant to be fermented by gut bacteria, and fermentation produces gas. VCA lists fermented fibres among the sources of intestinal gas. Start small and watch for a few days.

Is activated charcoal safe to give my dog every day?

That is not something the 2001 study tested; it looked at gas and odour over a few hours, not long-term safety. Ask your vet before using any charcoal product regularly, especially if your dog takes medication.

What actually reduces dog gas?

Diet first. VCA suggests a highly digestible, low-residue food, avoiding soy and legumes, and several small meals a day. Slowing down a dog who gulps food reduces swallowed air. Any diet change should be gradual over about a week, or it can cause gas on its own.

When is dog gas a reason to see a vet?

When it comes with diarrhoea, vomiting, weight loss, a swollen or painful belly, or when it continues after you have sorted the diet. A tight, bloated belly with retching and nothing coming up is an emergency, particularly in large, deep-chested dogs; go straight to a vet.