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Bad Breath in Dogs & Stomach Problems

Stomach and digestive problems, along with dental disease, are the primary reasons for bad breath in dogs.

Dog halitosis can also be a sign of food allergies, autoimmune diseases, or a serious medical condition such as kidney disease or diabetes.

Common Causes of Bad Breath In Dogs

Periodontal disease does cause bad breath so it's important to get regular cleanings for your dog's teeth. Non-anesthetic dental cleanings are available in many locations and can make a tremendous difference in your dog's overall health.

But some dogs are much more prone to tartar and dental problems than others and diet and poor digestion are contributing factors. Pet owners may notice unusual odors too which can be linked to health issues outside of the mouth.

Have you ever wondered: Why does my dog's breath smell like fish? Or why does my dog's breath smell like ammonia?

By treating the underlying health condition, you can improve your dog's bad breath and help prevent the foul odor from coming back. It is important to see your vet to get help in determining the cause of your dog's stinky breath.

So then, what causes bad breath in a dog?

Dental Issues and Tartar Buildup

Dog bad breath is often caused by the accumulation of odor-producing bacteria and tartar in your pet's mouth. Your pet's mouth could have a surprising number of tooth abscesses, as well as oozing pus and tartar accumulation.

Bad bacteria can build up inside your dog's mouth, inflaming the gums and causing cavities, loss of teeth and infection. Getting regular dental cleanings is important, especially now that anesthesia-free dental cleanings are available in many locations. Acid stomach can cause tartar to accumulate faster on the teeth.

Poor dental health can lead to serious, potentially fatal health conditions such as heart disease and kidney disease. Click here to learn more about pet dental health.

Acid Reflux

Does your dog seem to have a hard time swallowing? Is he gulping or smacking his lips after eating? Stomach acid is meant to help with the digestion of food in the stomach. With acid reflux, the acid can come up into the esophagus and damage the tissue. A dog may cough or gag to try to clear the acid away from the sensitive throat tissues, particularly after meals. If a dog has GERD or acid reflux, the stomach acid will irritate the mouth, teeth and tongue....causing dog bad breath from the stomach.

Digestive Disorders

Along with bad breath, your pet may have gas, diarrhea, tummy gurgling, mucus or blood in the stool and loud digestive noises. There are many reasons why pets can have digestive problems, including poor-quality food, food intolerances or conditions such as IBD.

The micro-organisms in your dog's intestinal tract must live in balance (symbiosis) between the good and bad bacteria. When the microbiome is out of alignment, dysbiosis can cause digestive upset.

Aside from vomiting and acid reflux, your dog may also have diarrhea and loose stool. These bowel movements can stick to the skin and fur area around your dog's rectum and cause itching and burning. This can be very uncomfortable for dogs causing them to lick at the area, making the pungent smell coming from the mouth even stronger.

Metabolic Conditions

Diabetes, kidney disease and liver problems are serious metabolic disorders that can cause bad breath in dogs.

Diabetes occurs when there is not enough insulin to fuel the metabolic process. Increased sugar levels in the saliva, combined with a suppressed immune system, allows bacteria in the mouth to thrive. This can create a sweet-smelling or fruity bad breath.

"Ammonia breath" is a classic sign of kidney disease. When the kidneys begin to fail, they can no longer effectively filter out the toxins and waste products in the blood. The toxins build up and can emanate through your dog's mouth.

Dogs with liver disease may have musty breath or breath that smells like a dead animal. The liver filters out toxins and when it is compromised, waste products and sulfur compounds build up in the body. The built-up compounds can be released into the lungs and exhaled through the mouth.

If you think your dog's bad breath is due to diabetes, kidney or liver disease, please check with your veterinarian. Laboratory tests, such as a blood panel and urine analysis, can determine if your dog's bad breath is due to a metabolic disorder.


When a dog is allergic to a certain food, it can trigger inflammation throughout the digestive tract, causing symptoms of acid stomach, diarrhea and vomiting. It's important to feed your pet a hypoallergenic diet and avoid common food allergens. Even if you are feeding your pet a raw frozen diet, if you are giving your pet poultry, a common allergen, your pet can continue to react to it. Dry food can be hard for many pets to digest as it contains a great deal of over-processed carbohydrates - even the grain-free varieties.

Anal Glands

Anal glands (or anal sacs) are located on both sides of your dog's anus. They contain specialized sweat glands that secrete a scent marker for your dog. Dogs express their anal glands when they poop and when they are scared.

Anal gland problems can give your dog an itchy butt and cause him to scoot on the floor. So when you ask: why does my dog's breath smell like fish? The fishy odor comes from your dog licking his butt. He may lick the anal glands for relief and the anal gland fluid can get on his tongue.

See below to learn more about dog bad breath home remedies that really work!

What Can I Give My Dog For Bad Breath?

Dental chews and doggie mints can only do so much for bad breath in dogs. They may temporarily mask the odor, but they do not address what is causing the pungent smell.

While there may be different health factors contributing, fresh, clean breath depends upon a healthy bacterial balance in your dog's mouth. Bad dog breath is an indicator of an imbalance in the microscopic community that lives in your dog's mouth, intestinal tract and respiratory system.

Microscopic organisms such as good (friendly) and bad bacteria, viruses and fungi (e.g. yeast) make up your dog's microbiome. When there is an imbalance too much bad bacteria relative to the friendly bacteria (found in probiotics) creates "dysbiosis" along with symptoms such as bad breath and other digestive problems. Remember that the mouth is the first portion of the digestive process and it reflects that state of your dog's digestion.

Top Supplements to Help with Dog Bad Breath

Ask Ariel's dog bad breath treatment includes the following home remedies:

  • K9 Digestive Enzymes - If your dog’s breath stinks, poor digestion could be the cause. When food is poorly digested, it creates gas and pain, and K9 Digestive Enzymes improve the digestion and absorption of fats and protein especially. Thus, K9 Digestive Enzymes is very helpful for improving the pH balance of the mouth and reducing tartar related to poor digestion.
  • Power Probiotic - Backed by scientific research, this powerful, multi-strain probiotic supplement promotes the growth of good, friendly bacteria to support a healthy mouth and digestive system.
  • Gastro ULC - When pets have acid reflux, it can cause stomach acids to back up into the esophagus and mouth. This can lead to erosion of the teeth and other periodontal problems. Pets with acid reflux tend to have bad breath as well. Gastro ULC works best when used with both Power Probiotic and K9 Digestive Enzymes or LypoZyme.
  • LypoZyme - This is a gentle, tasteless, easy-to-use enzyme supplement that helps pets digest protein and fats. While ideally the K9 Digestive Enzymes is the best choice for eliminating bad breath in dogs, some small dogs may be sensitive so starting out with LypoZyme is a great approach.

Recommended Diet For Dogs With Bad Breath

Diet can play an important role in supporting the health of your pet's mouth. Even "healthy” or “organic" premium brands can be problematic if they contain ingredients that cause inflammation, convert to sugars and create allergic responses. Using natural supplements to improve digestion along with feeding a low carbohydrate diet can reduce halitosis.

Ask Ariel is dedicated to helping you get rid of your dog's bad breath naturally. Please be sure to include your dog’s diet on the order form at checkout. Our nutritionist will include diet tips on the packing slip that comes with your product directions.

Need Help? Please email us at [email protected]

We understand how challenging bad breath can be for you and your pets. We are here to help. If you need information about a particular pet health condition and the products that can help, please email us for assistance. We do ask for your understanding, however, as we cannot provide any consultative advice due to veterinary regulations that require a physical exam.

Originally published Jan 11, 2023
Updated March 28, 2024
Written by: Susan Davis, Pet Health Nutritionist, CCN
All pet treatment protocols and pet treatment supplements have been reviewed and approved by a veterinarian