Picture the scene: you’re relaxing in the lounge, feet up on the sofa, telly on, and then you catch a whiff of the noxious stink that is about to fill the room — your dog has just dealt a ‘silent but deadly’.

Now flatulence may not be a particularly glamorous subject, but for dog owners it is a recognisable part of living with pets. Of course, it’s a natural by-product of the digestive process and, without the constraints of social convention, dogs just do what comes naturally.

But what is considered normal? Can age and breed affect the problem? And when is wind potentially the sign of a health issue that may need expert help?

To answer these questions, you first need to identify what we are talking about in scientific terms. 

Flatulence is excess gas in the stomach or intestines, while flatus is the gas that leaves the body and which contains small amounts of sulphur. 

Generally, dog flatulence is caused by too much gas going in during feeding or too much gas being made once food has been eaten.

Dogs have a monogastric digestive system — a single stomach that’s capable of massive expansion to cope with gorge feeding. In the wild, the dog’s predecessors would eat as much as possible in a short space of time to maximise their chances of survival. 

Research suggests that a dog’s stomach is somewhere between pH-1 and pH-2. That’s highly acidic — much more so than our own — which means they are capable of digesting things that we can’t — the signature of a carnivore-type lifestyle. It also means that they can break down things like bone and firmer tissue over a period of time and even deal with things that would make us sick. Ever wondered why your dog can get away with drinking from that muddy puddle?

The stomach empties into the small intestine, and then into the large intestine, both of which are really short compared with other species. The stomach is the main site of digestion for dogs, where the acid breaks down proteins. These proteins then go into the small intestine, which starts to absorb the broken-down nutrients. It is then primarily water content that gets reabsorbed through the large intestine, and whatever isn’t processed or absorbed comes out the other end.

It’s estimated that humans break wind between five to 15 times a day, so it’s not surprising that dogs too are regular ‘bottom burpers’. Excess gas can be created not only by the type of food but how it is eaten. Excess air from gulping down food can be a trigger, as can a dog who feels in competition with another, prompting him to eat too quickly.

Slow down feeding

Animal scientist and Your Dog contributor Dr Jacqueline Boyd recommends slowing down food intake with puzzle feeders, trickle feeding throughout the day, or increasing the number of mealtimes but reducing the amount per meal.

“If you’re feeding a dry food, soak it in cold or tepid water — that can work because it tends to slow the dog down in terms of ingestion,” she advised. “It also has the added benefit of adding hydration and increasing digestibility (how the body is processing it), which is also another factor around the production of intestinal gas.”

Using puzzle feeders can help slow down your dog’s eating.

Diet is a significant factor, not only in managing flotus, but also in maintaining your dog’s health and well-being. The science behind it is complex. Some nutritionists, including Anna Webb, are staunch advocates of feeding a raw diet. “For me, the first step to ensure that my dogs have a healthy gut is to feed them what dogs are supposed to eat — a balanced, complete diet that comprises 80 per cent meat, and a food that is unprocessed, so when you look at it you recognise the ingredients. They haven’t been processed — the molecular structure has not been deformed,” said Anna.

She believes that kibble diets can be ‘pro inflammatory’ because “the ingredients are mostly sugar and starch, which we know on a human level creates inflammation”.

However, Jacqueline believes that specific diets are not automatically a panacea. “There is no such thing as the perfect nutrition. There may be diets that are best for a given situation but it’s always a compromise,” she said.

“I formulate diets that can be 100 per cent kibble, some home cooked, some mixed. My own dogs are on a mixed diet, but it’s always balanced and formulated.”

She explains that the fibre in kibble is often deemed to be the problem. “If a dog is getting a lot of indigestible fibre, it will ferment and produce gas but this is where it gets interesting, because not all fibre is equal. There is soluble fibre and insoluble fibre. Insoluble fibre can be the problem but that in itself is not all bad, because insoluble fibre is also good for gut health. It works as a pre-biotic, feeding the good bacteria in the gut. So, the trick with the gut is keeping everything in balance.”

In fact, ‘whole foods’ such as a carrot — often given as a healthy treat — have little nutritional benefit to a dog, but the fibre they contain is good for the mechanics of the gut. There’s also evidence to suggest that allowing a puppy to eat different types of food (albeit slowly transitioned) will allow the digestive system to become more robust and increase immunity in the early stages of life.

So, how much flotus is normal? Again, there are many factors to consider; the age and size of the dog, whether he has had a recent change in diet — even the addition of new treats can trigger more gas.

As we get older, we become less tolerant of certain foods and in turn they are more likely to trigger sensitivity — the same applies to older dogs, which in turn may result in greater amounts of flotus.

Brachycephalic breeds, such as the Pug and the  French Bulldog, tend to be gassier as they swallow a lot of air while eating.

Caroline Reay, chief veterinary surgeon with Blue Cross, is keen to point out that “flatulence is a normal part of life and no need for concern unless the dog has other signs such as sickness, diarrhoea, abnormal stools, weight loss, or a change in appetite.”

Advisory consultant Dr Victoria Strong, who runs VIP Professionals, concurs: “To some extent, dog flatulence is something owners have to put up with. Only if it is excessive in respect of frequency and/or smell should a vet appointment be considered.

“Every dog is different, so keep an eye out for a change in what’s normal for your dog and consider diet first and foremost if no other symptoms are present.”

Getting to the bottom of it!

Dr Victoria Strong BVSc BSc (Hons) DVetMed AFHEA MRCVS is an experienced vet with more than 10 years’ experience in clinical practice, education, and research. She advised:   

“The first step in investigating a dog’s flatulence is to look at their diet. If a dog presents a number of other symptoms too, further investigation may be considered. Initially, this may include a blood test or a faecal sample and maybe an ultrasound scan. More invasive investigations such as a biopsy or using a camera to look at the inside of the stomach and intestines would likely only be carried out in a dog for whom flatulence is not the primary or only problem.

“Some breeds of dog have a reputation for being gassier than others. Most of these are brachycephalic (short-nosed) breeds since they tend to swallow a lot of air when they are eating. Other predisposed breeds are those prone to conditions such as inflammatory bowel disease. Age can also be a factor; as we get older, we can become intolerant to different types of foods and this can affect how we digest them — dogs are probably similar. Overweight and sedentary dogs will also tend to be gassier.

Many ingredients, including chicken and beef, can trigger a reaction.

“So, it’s important to take all these things in context and seek the advice of a vet and/or nutritionist when necessary. They can provide you with some practical steps to identify if your dog is intolerant to a particular food type. Some small changes or tweaks may be all that is needed. Some people make a big change — switching their dogs from kibble to raw for example and then, if the dog improves, think that the problem was the kibble. In truth, it’s a lot more complex than that. It may be that there is a particular ingredient that was the cause of the problem, for example some dogs are intolerant to chicken, but that ingredient can be present in a lot of food whether it is processed or not.

“If you think that a particular food is the cause, you can try to identify what it is by removing the extras from your dog’s diet — the treats, the dental chews — and slowly reintroduce them and see if the issue reoccurs. I recommend keeping a food diary for your dog during this period to help you identify which of the foods being reintroduced could be the trigger.  

“An alternative approach is an exclusion diet — stripping back the diet to core protein and carbohydrate food types, with either home-cooked food or a proprietary diet. This is most often used if a genuine food allergy is suspected, although these are less common than people think. This could address the food sensitivity and indicate which common food stuffs need to be avoided long term. Any ingredient can trigger a reaction however; chicken, beef, lamb, soya, and wheat are known triggers.”