11 Reasons for Smelly Dog Gas, According to a Vet

Every dog owner knows the look. The one where your dog lifts their head, you lift yours, and you both silently agree to never speak of what just happened. A little gas now and then is completely normal, especially with bigger breeds who inhale their food or have sensitive stomachs. Most of the time it’s harmless, and honestly, kind of part of the deal when you share your home with a dog.

But when the gas becomes constant, clears the room on a daily basis, or shows up alongside other changes like loose stools, a bloated belly, low energy, or a shift in appetite, your dog is probably trying to tell you something.

The good news is that most causes are fixable once you know what you’re looking at. Below, we’ll walk through the 11 most common reasons behind smelly dog gas and what you can do about each one.

Have you changed your dog’s diet recently? If so, this could be the cause of their bad wind! A sudden change in diet is never a good idea, as it doesn’t allow the population of your pet’s gut flora a chance to change and adapt. The gut microbiome is a delicate balance of bacteria, fungi, and viruses. The ‘good bacteria’ are involved with digestion and help our pets absorb nutrients from their food, but there are wider-reaching effects on your dog’s health status.

A sudden change in diet can lead to problems with your pet’s digestion, resulting in more gas. Switching pet food manufacturers, changing from a wet diet to a dry food diet, or even swapping between flavors could cause problems for some pets if done too quickly. You may also find the quality of your pet’s diet affects their digestion, for example, high levels of fiber could cause an increase in gas.  

If you want to change your dog’s diet it is best to do this gradually, ideally over a period of a week or so. You should start by mixing in a small amount of the new food with the old diet, then gradually increasing the proportion of new to old food, until your pet has been transitioned onto the new diet. It’s also worth making sure your pet is on a good quality complete diet that is appropriate for their age and size.

Does your dog scavenge or raid bins? Or do you slip them some of your leftovers now and then? This could be the reason why your dog produces a lot of gas!

Rich food can be tricky for some pups to digest and also upsets that all-important gut flora again. Some foods are particularly well known for causing digestive issues in dogs, including dairy products. Many dogs can’t digest lactose, the natural sugar found in dairy, which can lead to loose stools and increased wind. While cruciferous vegetables like broccoli, sprouts, and cabbage are safe for dogs, they are also well known for creating more gas.

Dogs with underlying intolerances or dietary sensitivities can have trouble digesting certain ingredients or additives in their food. This can potentially lead to an increase in gas production. No immune response is triggered, but digestive issues like vomiting, diarrhea, and flatulence can occur in affected animals.

True food allergies are different from intolerances as they involve an immune system reaction. Allergies are more likely to produce symptoms like skin itchiness, hives, recurrent ear infections, and rarely, anaphylaxis.

To work out if your pet has an intolerance, a strict dietary trial will need to be performed, under the guidance of a vet.

In high numbers, internal parasites can cause digestive upset in dogs, leading to more gas production.

A commonly found parasite in dogs is roundworm (Toxocara canis) which is a white spaghetti-like worm that lives in the intestines.

Tapeworms can also be found. These can be larger, flat, ribbon-like worms. A tapeworm will bury its head into the lining of your pet’s gastrointestinal tract, where it remains in situ absorbing nutrients. It sheds segments that come out of your pet’s anus like wiggling grains of rice. These are packed with eggs which can be ingested by other animals.

Giardia is a microscopic protozoon that frequently causes loose stools, especially in younger animals. Blood or mucus may also be seen in the feces.

Fecal screening can help to identify if parasites are present. Anti-parasite treatment will be required for affected animals, and regular deworming is recommended to stop future parasite infections.

Many different underlying medical conditions could affect your dog’s digestion, too many to list in them in detail here.

A common example is inflammatory bowel disease (IBD). This can cause issues with digestion and absorption of nutrients, which could lead to weight loss, vomiting, diarrhea, and increased gas. Treatment may require a change of diet or anti-inflammatory medication.

Pancreatitis (inflammation of the pancreas) can cause abdominal pain and digestive upset. Affected animals may require hospitalization for pain relief and supportive therapy. Other dogs with low-grade or chronic pancreatitis may be treated with a change in diet, pain relief, and monitoring at home.

Neoplasia (cancer) can also affect the digestive system leading to weight loss, gastrointestinal upset, and changes in gas production.

Viral and bacterial infections can cause upset to your pet’s digestive tract which could create higher volumes of smelly gas being produced. A well-known infectious disease example would be parvovirus. Parvovirus causes severe and often bloody diarrhea, with vomiting, appetite changes, and lethargy. Left untreated it can be fatal. Thankfully we can vaccinate against this disease which will greatly reduce the chances of your dog catching it.

Dogs can be affected by bacteria like Salmonella, E. coli, and Campylobacter. Some dogs can be symptomatic, but many others will not show serious symptoms at all.

It has been shown that dogs who are raw-fed are more at risk of carrying these bacteria, which can be spread to people. So, care needs to be taken if you are raw-feeding your pet, especially if you have young, old, or immunocompromised family members.

Many different medications can cause digestive upset in dogs, which could increase smelly gas. Antibiotics are well known for upsetting the gut flora in the digestive tract. As well as treating the targeted infection, antibiotics can cause dysbiosis. Dysbiosis describes a situation where levels of good gut bacteria have been reduced, which can lead to digestive upset, including increased wind.

Another commonly used drug in veterinary medicine is the non-steroidal anti-inflammatory (NSAID). These are commonly used painkillers for dogs, but one of the most common side effects of this medication is gastrointestinal upset. Certain chemotherapy medications may also affect the digestive tract.

If your pet is on medication and develops side effects you must consult your vet for advice.

Dogs that have a habit of eating too fast, also accidentally ingest air while eating. This can lead to smelly gas in a dog who is otherwise well. If your dog inhales their food, you should consider using a slow or puzzle feeder. These stop your pet from being able to gulp their food down which should reduce the amount of air they swallow too.

Brachycephalic breeds are renowned for their wind! But why is this? Brachycephalic breeds have flattened faces and compromised airways, which can make it tricky for them to breathe while eating. Not only does this increase the risk of them choking, but they can also swallow more air than other dog breeds while eating.

Extra air in the digestive system will be released as gas. Slow-feeding bowls or splitting their daily rations into multiple smaller meals spread throughout the day may help with this.

Stress-induced colitis could cause an increase in gas production as well as other symptoms, like loose stools and appetite changes. Affected dogs may have more mucous in their stools and small amounts of blood too. This common condition is triggered by stress and anxiety, which leads to inflammation of the large intestine in affected animals.

Common causes of stress in dogs include separation anxiety, moving house, a new family member or pet joining the household, or recent hospitalization. It can usually be treated with a bland easy-to-digest diet and supplementation with probiotics, but your vet will advise you further.

Some dogs get smellier as they get older! Their digestive system can start to struggle with age, meaning they don’t digest and absorb their food as well as they did in their youth. This can lead to more gas as well as other issues such as weight loss and loose stools.

Some elderly dogs can benefit from being transitioned onto a highly digestible diet. However, it is always important for your vet to rule out any other health conditions first. Many disease processes like cancer, inflammatory bowel disease, and pancreatitis can be seen more commonly in elderly dogs.