When you buy through links on our site, we may earn an affiliate commission.

Why Does My Dog Smell Like Fish?

By nature—and through the environment they inhabit—our dogs periodically emit a smell that is, at best, unpleasant and, at worst, downright repulsive.

These occasionally-odorous spells are usually no cause for concern, but if your fuzzy companion is persistently giving off a “fishy” aroma, you may want to sit up and take notice.

As it may (or may not) be a sign of a larger problem that requires the attention of a pet professional.

To help provide more information on this topic, below we will go over some of the potential causes for a fish-like smell in dogs, give tips on how you can prevent and/or rectify each cause, and advise you as to the certain circumstances that may necessitate a trip to the veterinarian for diagnosis and treatment.

What Causes My Dog Smell Like Fish?

There can be several reasons why a dog may smell like fish.

Some of these are more benign than others, so the ability to pinpoint the exact details surrounding the aroma is quite imperative.

Here are just some of the potential circumstances and the usual cause or causes of each:

Fishy Breath

If the fish smell in your dog is limited to his or her breath, it may or may not be cause for concern.

The most natural explanation, of course, is a fish-based diet.

Dogs with fishy-like breath can carry around remnants of their last meal in their teeth, and just like with humans, those remnants can lead to foul-smelling breath.

Check the label on the dog food you are using to see if contains ingredients like salmon or other fish species.

If it does, you have probably discovered the source of this problem—a problem that can be quickly rectified by brushing your dog’s teeth regularly and/or turning to one of the “doggy fresh breath” products currently on the market.

Another possible—and more serious—explanation for fishy breath in dogs is periodontal disease.

According to the #1 medical pet website in the world, “nearly 90 percent of adult dogs have some form of periodontal disease.”

While not exactly an issue with a dog’s teeth, the disease, which is caused by bacteria in the mouth, can, over time, damage your dog’s gums and the bony structures that help form and structure the teeth.

Periodontal disease in dogs progresses throughout four stages, each worse and more damaging than the one before.

And if not caught and treated during stage 1—the only reversible stage which is essentially doggy gingivitis—the issue will continue to get worse as it slowly and gradually ravages your dog’s tooth structure, causing both pain and significant decay.

More to the point of this particular article, once periodontal disease advances to Stage 2, a foul and fishy smell can begin to develop in your dog’s mouth, inevitably causing an issue with his breath.

This is why regular dental hygiene should be a staple for your pet, both at home and at the vet.

Fishy-Smelling Urine

If your dog’s pee suddenly takes on a tainted or fishy aroma, odds are pretty fair that the problem lies in its urinary tract system.

There are a myriad of infections, both viral and bacterial, that can beset elements of your dog’s urinary tract, kidneys, bladder and, in male dogs, the prostate.

Most of these infections can be treated by your veterinarian with antibiotic and antiviral medications, which is why it is so vital to make an appointment with your vet as soon as you notice these symptoms.

Early action can bring about better outcomes with regard to the treatment plan and may significantly curtail your dog’s suffering.

In more severe cases, the rank-smelling pee could be caused by tumors—both cancerous and benign—within that same urinary tract system.

Early diagnosis and treatment of these disorders is, undeniably, recommended.

Overall Fishy Smell in Your Dog

If neither your dog’s pee nor his breath seems to be the culprit, yet you are still noticing a pungent fish-like smell every time your dog enters your personal space, the problem might be caused by one of disorders known as anal sac diseases—a generic term used for any problem with your dog’s anal glands.

Dogs have two anal glands or anal sacs, located on either side of its anus.

These glands, which are typically hidden by your dog’s tail, are always emitting “some type” of odor (or odorous fluid) when they are prominently exposed.

The anal sacs are most noticeable when a dog is, let’s say, making number 2, but they can also come out of hiding when a dog is scared or anxious.

So why do these anal sacs or glands emit an odor?  Nobody knows for sure, but experts say it is a way of marking their territory—of letting their presence be known.

It also explains why dogs are so curious about each other’s butts during an encounter, as they are constantly trying to derive information from the smell these glands produce.

While the odor produced by anal glands does not always smell like fish, when it does, it may indicate some type of problem or health issue—an anal gland disease—that needs to be addressed by your vet.

Some of the reasons for why a dog’s backside might smell like the “catch of the day” include:

Soft Stool Impactions

When a dog does his business, the pressure of the fecal matter he is expelling also causes the anal glands to come out and dispense their usual fluid.

However, in some cases, especially when a dog’s stool is very soft and watery, the lack of pressure inhibits the anal sac from protruding and completely emptying its fluid.

This, in turn, can cause that fluid to become impacted within the anal gland, which can lead to a very fishy smell.

In often painful cases such as these, a trip to the vet is definitely warranted to allow that professional to manually correct the problem.


As with any exposed part of a dog’s body, the anal glands may occasionally become infected, thus producing a fishy smell.

These infections can lead to larger problems within the anal sac, namely abscesses that can fill with infected fluid, or pus.

Treatment with antibiotics, both topical and systemic, may be needed to correct this problem.


Cell clusters that cause tumors on or within the anal glands can also bring about a very unpleasant, fish-like odor.

Anal gland tumors (and cancers) can be extremely serious, so be sure to get your pet to the veterinarian as soon as possible.

Last Word

The fishy smell your dog is emanating can be the result of a benign or very serious problem.

Fishy breath can often be addressed with proper nutrition and regular dental care for your dog.

And if the problem lies in his urine you are no doubt looking at some type of urinary tract infection that, if caught early, can be remedied through antibiotics (UTI).

However, if you have picked up a fishy fragrance from your dog, and you notice he is scooting his bottom along the floor—and exhibiting this behavior frequently—the problem is almost certainly the result of some type of anal gland disease.

These diseases, whether the fault of impaction, infection or even cancer, need to be addressed as soon as possible with your pet practitioner.

Sharing is caring!

Leave a Comment

This site uses Akismet to reduce spam. Learn how your comment data is processed.

National Canine Research Association of America