Why do my dog’s farts smell so bad?

Our furry family members bring us so much joy, but there are some downsides to dog ownership. Smelly farts are one of the problems that pet parents often report. If your pet can clear a room with their stinky gas, it’s worth exploring the underlying cause.
 
We’re going to look at your pet’s digestive system in more detail so you can understand what’s going on and, hopefully, help your pet smell a bit sweeter. Read on to find out more!

Why do dogs fart?

Flatus (the technical term for digestive gas) is a normal side product of digestion. Farts are produced from air swallowed during eating and bacterial fermentation in the gut. Helpful bacteria in the digestive tract, known as the microbiome, break down carbohydrates and fibre, producing hydrogen, carbon dioxide, and methane. Tiny amounts of sulphur compounds are also produced to varying degrees, such as hydrogen sulphide, methyl mercaptan, and dimethyl sulphide. This is what gives farts their smell.
 
Passing wind is something that most animals do, but some produce stinkier farts than others! Diet plays a big part in this, but there are other factors that play a role too… let’s explore this next.

The top 9 reasons your dog’s farts smell bad

1. Food allergies and intolerances

If your dog struggles to digest their food properly, this can cause an increase in the production of smelly farts. With a food intolerance, your pet may also suffer from other signs of digestive distress like abdominal discomfort and diarrhoea. Intolerances don’t involve an immune response, and difficulties with sugars like lactose are common.
 
A dog with food allergies might show gastrointestinal symptoms, but they could have signs elsewhere too. Itchy skin and paws, recurrent ear infections, or breaking out in hives are also signs that your dog is having an allergic reaction.  An overactive immune response usually occurs to proteins, with common food allergens being chicken, beef, and dairy.

2. Eating foods that encourage gas

Certain foods can encourage extra smelly gas production. The most common culprits are:

• Beans, lentils and chickpeas – contain raffinose, a complex sugar that can be tricky to digest
• Cruciferous vegetables, including broccoli, sprouts, cabbage and kale – another rich source of raffinose but also contain sulphur compounds, which can lead to strong-smelling gas.
• Whole grains – oats, wheat and other whole grains contain fibre, starch and raffinose, which when fermented by bacteria produce gas.
• Certain fruits - Fruits like apples, pears, watermelon, and mango contain sugars that are poorly absorbed and will ferment in the gut.
• Sulphur-rich foods like eggs, meat and fish – these contain sulphur compounds which produce hydrogen sulphide when digested, the gas that gives farts their odour. Low-quality protein sources or spoiled foods can cause more issues.
  

3. Low-quality diet

Some low-quality diets can contain higher levels of fibre and carbohydrates (sugars), the very things that contribute to more gas production. High-fibre foods take longer for the digestive system to break down, leading to gas.
 
It’s also worth noting that high-fat diets can slow digestive transit, giving food more time to ferment, and leading to smellier farts.
 
Remember that eating spoiled foods, or human table scraps that are fatty or rich in carbohydrates, could have similar effects.

4. Other digestive disorders

Anything that impacts the normal flow of the digestive system could result in issues like diarrhoea, abdominal pain, and increased gas production.  Common digestive issues that can result in smelly gas production include:

• Inflammatory bowel disease
• Pancreatitis
• Colitis
• Bacterial, viral, or parasitic infection
  

5. A sudden change in diet

Changing your pet’s diet suddenly can cause digestive issues. While some dogs can happily handle a rapid change… others not so much. A gradual transition over to a new diet is always best as it allows your dog’s gut flora to adapt. This reduces the risk of issues, including smelly farts.

6. Swallowing too much air

Does your dog inhale their food? Gulping down food at top speed can also cause your dog to swallow more air while eating. Certain breeds are also more likely to swallow air when they eat than others, such as Pugs and Bulldogs. These flat-faced dogs are more prone to ‘aerophagia’ due to their anatomical features.

7. Not enough exercise

Exercise helps pets to maintain a healthy digestive system by encouraging gastric motility. If your dog isn’t exercising as much as they should be, their digestion will slow. This will lead to excessive fermentation of undigested food in the gut and more gas production.

This could be a particular issue for dogs recovering from injury or surgery, elderly dogs, or dogs belonging to time-poor owners.  

8. Behavioural concerns

Anxiety or stress may impact your pet’s digestion. We know that stress-induced colitis is an issue for many dogs, with symptoms including diarrhoea, increased mucus in the stools, bloody faeces, and yep, you’ve guessed it…. stinky farts! Cortisol, the hormone associated with stress, affects gut transit time and your pet’s immune function.

9. Medication

Some medications may affect your pet’s digestion, resulting in extra gas and other issues like loose stools. Antibiotics can affect your dog’s gut flora, and certain pain relief drugs can affect gastric motility. Always speak to your vet if your dog experiences side effects while on medication.    

My dog has stinky farts… when should I call the vet?

If your dog has persistently smelly farts, then it’s worth chatting things through with your vet. This is particularly urgent if your dog is showing any of the following symptoms –

• Diarrhoea
• Vomiting
• Excessive mucus in their stools
• Bloody faeces
• Lethargy
• Weight loss
• Appetite changes
• Abdominal pain
  

Your vet will help you to work out if there are any underlying medical causes for your dog’s stinky farts.

Ways to improve your dog’s stinky farts at home

If your dog is otherwise well, and your vet has ruled out medical concerns, then you could try the following:

• Look at your dog’s diet – You should feed a good quality complete diet, appropriate for your dog’s age and size. Look at the ingredients and to check that a named animal protein is high up on the list. Make sure that you are feeding the correct amount. If you need to change your pet’s diet, then make sure to gradually transition them over a period of 7 – 10 days. If a food allergy or intolerance is suspected, you may need to do a strict dietary trial. Your vet will talk you through this in more detail.
• Reduce aerophagia – Reduce the amount of air your pet swallows by using a slow-feeding bowl or puzzle-feeders. This stops them from wolfing their meal down. These can be quite helpful for brachycephalic breeds who are more prone to this issue.
• Exercise – Make sure your pet is getting enough daily exercise. If your pet has a medical condition or they are recovering from surgery, then you will need to speak to your vet about this one.
• Avoid table scraps and gas-inducing foods – Don’t give your dog human foods, but especially avoid types known to increase gas production, like hard to digest vegetables, fruits, and legumes. Rich, fatty foods should also be avoided, as these can slow gut transit time as well as trigger other digestive issues like pancreatitis and colitis.
• Probiotics – Probiotics for dogs can help support your pet’s digestion. If your dog’s microbiome is healthy, then their digestion will be optimised. Speak to your vet for more advice on this.
• Reduce stress – If your pet suffers from digestive upsets related to stress, then you will need to address this. Speak to your vet or a qualified pet behaviourist for advice on managing your dog. Looking at ways you can adapt their environment, desensitisation training, and calming supplements or products can all be beneficial.
  

Summary

Stinky farts are a warning sign that something is unsettling your pet’s digestive system. While the odd bout of smelly gas may be nothing to worry about, it’s important to seek professional advice if it’s a regular occurrence, or if your dog is showing other symptoms like diarrhoea or appetite changes.
 
Once your vet has ruled out underlying medical concerns, you can try making a few tweaks at home to help support your pet’s digestion.