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Why Does My Dog’s Breath Smell Like Fish?

mouthwash blog post _breath smells like fish

Fishy dog breath is a common problem. From eating out of the garbage to anal sac disease we look at the causes and solutions to dog breath that smells like fish.

Some unfortunate pet parents may be wondering, “why does my dog’s breath smell like fish?” Ongoing halitosis indicates a problem in oral hygiene or your pup’s health causes a funky smell. In fact, there are many reasons your dog’s breath may smell like fish. Foreign objects stuck in your dogs’s teeth or built-up bacteria and anal disease may be why your dog’s breath smells like fish.

Rotten eggs and fish stink are some ways to describe your pup’s awful breath. In this post, we dive into common causes of fishy smell in dogs because understanding the reasons is the first step to treatment. What one person describes as a fishy smell may differ from the next. Generally, if you detect a musty, foul smell from your pup, some may call it fishy. 

5 Causes of Fishy Dog Breath

Fishy dog breath could be caused by any of these 5 different issues

Strong, sour odors from your dog’s mouth that you can describe as fishy or rotten result from various causes. Anal sac disease, objects stuck in the teeth, oral infections, and medical issues like kidney disease are some of the top reasons for fishy doggy breath.

Anal sac disease

Dogs have anal glands or sacs full of specialized sweat glands. These anal sacs secrete a smell giving each dog a distinct scent that marks them out from other dogs. This explains why dogs are so interested in sniffing each other’s butts, as though that’s the doggy way of saying hello. 

Many people would describe the anal secretions as smelling fishy. Your dog sometimes licks the anal sacs leaving a fishy smell in the mouth. If something is wrong with your pup’s anal glands, the secretions increase in quantity leading to an even more pungent stench. 

Your dog’s anal sacs are naturally expressed, which releases the secretions. Your dog may have issues with the anal sacs, whereby the process of expression doesn’t occur quite effectively. The anal sacs get hard, swollen, and painful due to an accumulation of unreleased anal sac secretions. A change in stool consistency (runny poop) can also lead to anal sac disease as the sacs aren’t properly expressed. 

Once the anal sacs get infected, they may get abscessed if they don’t receive prompt treatment. If the infection spreads, it can cause severe damage to the anus and rectum. If your dog has anal sac disease, you’ll notice them scooting on the floor and licking the area excessively. The licking transfers the fishy smell from the anal area to your pup’s mouth, causing stinky breath.

Consuming gross non-food items

Dogs love to eat anything in sight, including their poop and that of other animals, gross! Your pup may have eaten something rotten, which manifests as a vomit-invoking odor. If your dog’s mouth smells rotten, use commercial products like the PawSafe dental rinse to remove the nasty substances. 

Your dog may not be getting satiated after meals, leaving them ingesting poop as a delicacy. It may sound like a stretch, but some dogs love poop taste, especially cat feces. Coprophagia is mostly a normal canine behavior, but sometimes it indicates anxiety or nutrient deficiency. 

Improper diet

A nutritionally incomplete diet can lead to gut issues and bad breath due to a lack of some nutrients. Deficiencies of vitamin A, Vitamin B (2,3 and 5) are associated with an early onset of gum disease. Gum issues cause bad breath and other medical problems like periodontitis. 

Fish can be good for your dog as it is rich in omega-33 fatty acids, but it can lead to fishy breath. If you constantly feed your dog fish or fish-based supplements, the smell will reflect in the mouth. Some fish like fresh tuna contain high levels of mercury which can harm your dog, so feed dogs fish in moderation. 

High carb foods and those high in sugar also pose dental risks to your dog. Dogs lack amylase in their saliva, an enzyme responsible for breaking down carbohydrates in the teeth. Sugary foods affect the teeth because mouth bacteria consume the sugar, producing an acid that eats away tooth enamel. 

Foreign objects lodged between the teeth

Bone splinters, food debris, and other external substances can stick into your dog’s teeth and rot. Dogs that love to chew bones may remain with splinters in the teeth that injure the gums and lead to infections. Oral infections are painful, and you may observe your dog having a decreased appetite because it’s painful to chew food. 

Neglected oral care resulting in dental problems

Dogs can’t brush their teeth, so that responsibility is for us as responsible pet parents. We recommend brushing your dog’s teeth at least once every week, although the more days, the better. Small dog breeds and brachycephalic dogs (those with flat noses) need more dental attention because their teeth fit into a smaller area. 

If oral hygiene is lacking, plaque will accumulate on the gum line and the teeth and harden into calcified tartar. Halitosis is a common side effect of oral diseases such as gingivitis and canine periodontal disease, resulting from prolonged tartar buildup on the teeth.

Homemade remedies such as apple cider vinegar and carrot sticks are available, which we discuss in the linked article. Other dental care practices like providing dental chews for your dog or using sprays cannot substitute regular brushing with dog toothpaste. Brushing eliminates food debris trapped between the dog’s teeth. 

How to Get Rid of Fishy Breath in Dogs

Here are some ideas for getting rid of fishy dog breath

Keep up with brushing and  doggy mouthwash

Some folks believe they don’t need to brush their dog’s teeth. We have debunked the myth that dogs have cleaner mouths than humans, which you can read to find out the truth. Regardless, you must clean your dog’s teeth on a regular basis to avoid dental diseases like gum inflammation.

Putting doggy mouthwash in their water is an easy and non-invasive way of tackling the bacteria that can lead to infections and bad breath.

Provide dental chews and chew toys

Chewing is nature’s way of cleaning the teeth of animals in the wild. Dental chews and toys create a fun avenue for chewing while cleaning the mouth by scraping off bacteria buildup. Dental chews are a better alternative to bones which can splinter and cause intestinal blockage. 

Regular professional cleaning

Regular dental checkups sound like a very human thing to do. Some folks believe that dogs have cleaner mouths than humans, which we discussed in our article as false. Dogs still need oral care, and yearly vet visits are a preventive measure. Tartar can’t be removed with regular brushing, but the vet can eliminate it during cleaning. 

The performing vet can spot developing dental diseases that would have otherwise gone unnoticed by the general public. The vet can also diagnose underlying medical conditions responsible for stinky breath in dogs. Small dog breeds are susceptible to dental problems. They’d benefit from biannual vet visits.

Final Thoughts

Your dog can have a fishy breath for various reasons. Anal sac infections are a leading cause of fishy breath when your dog licks their painful anal sacs. Other causes of fishy smell include improper oral hygiene, an inappropriate diet, and foreign objects stuck in the teeth. 

Don’t neglect to take your pup for professional teeth cleaning every year. Tartar buildup develops into periodontitis and gingivitis, yet the vet can remove calcified tartar during a cleaning session. If your pup shows signs like lethargy and appetite changes, they may be sick and in need of medical attention. 


Tamsin De La Harpe


Tamsin de la Harpe has nearly two decades of experience with dogs in rescue, training, and behavior modification with fearful and aggressive dogs. She has worked closely with veterinarians and various kennels, building up extensive medical knowledge and an understanding of canine health and physiology. She also spent two years in the animal sciences as a canine nutrition researcher, focusing on longevity and holistic healthcare for our four-legged companions.

Tamsin currently keeps a busy homestead with an assortment of rescue dogs and three Bullmastiffs.

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