Why Does My Dog’s Breath Smell Like Fish?

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dog breath smells like fish

Have you ever noticed that your dog has stinky breath? Some pet owners notice and complain that their dog’s breath smells like fish.  A fish odor can occur for several reasons, which we will review below.

The medical term for bad breath is “halitosis.” Bad breath can be caused by a dogs diet, ingestion of different foods or trash, be a warning sign of oral or dental disease, or can be a sign of a respiratory disease, infections, or other systemic problems such as diabetes.

What Can Cause Fishy Smelling Breath in Dogs?

There are dozens of causes of canine bad breath. Bad breath is considered a symptom. What that means is there are many potential underlying causes of bad breath. For example, dog breath smells like fish could be from something your dog ate, an ulcer in the mouth, or from a tooth infection. Some of the possible causes of fishy smelling breath are minor and others are more serious and require treatment.

Causes of Bad Breath in Dogs include:

  • Dietary indiscretion. A common cause for bad breath in dogs is their dietary indiscretion. Ingestion of dead animals, garbage, animal feces, compost, litter box wastes, or spoiled food can give your dog breath that smells like fish.
  • Gum disease.  Gingivitis is inflammation of the gum tissue which is commonly caused by dental plaque. This results in swelling and redness of the gums as well as bad breath. Plaque develops when the normal bacteria in the mouth mix with proteins and starches found in saliva. This mix produces plaque material that adheres to the teeth. Eventually, plaque turns into tartar, which firmly adheres to the teeth. It is most obvious just below the gum line where it accumulates. A dog with breath that smelled like fish. This dog has plaque, tartar and an infected tooth as the dark black tooth on the right.
  • Periodontal disease.  Peritonitis is a disease of the tissues that support the teeth and is the leading cause of tooth loss in dogs. This disease affects over 80 percent of dogs over three years of age. Peritonitis is caused by bacteria that make up plaque. The total impact of periodontal disease is difficult to determine in dogs. It has been well studied in humans and is sometimes referred to as the “silent killer” due to its destructive nature. In humans, in addition to tooth list, periodontal disease can cause aspiration pneumonia from small amounts of bacteria that are released into the bloodstream (bacteremia) resulting from when we chew or brush our teeth.
  • Tooth abscess. An abscessed tooth can cause dog breath that has the foul odor of fish. Some tooth abscesses are contained within the mouth and others will abscess up through the skin. It is common for a dog to present to the veterinarian for a draining wound on the cheek just below the eye.  Inspection of the wound can reveal an abscessed tooth. Treatment includes dental cleaning and possible tooth extraction (removal).
  • Oral ulcerations. Ulcers in the mouth can occur due to infections, reactions to certain drug therapy, or from a dog ingesting or licking caustic substances. Caustic substances may include cleaning chemicals, soap, and detergents, or liquid potpourri.
  • Many cleaning chemicals such as bleach or lye can cause oral ulcerations.
    • Laundry and dishwasher pods are colorful, soft and can look like a dog toy. Dogs can chew on or ingest these laundry or dishwater pods which can cause severe oral ulcerations. To learn more – go to Laundry or dishwater detergent pod toxicity in dogs.
    • Liquid potpourri is a common household item. Potpourri is scented and can be appealing to some dogs.  It can be found as concentrates added to water and heated slowly in simmer pots. The ingredient of potpourri includes essential oils and cationic detergents that can case ulcerations of the mouth, gum tissues, and/or esophagus. For more information, read about Potpourri Toxicity in Dogs.
  • Oral infections. Oral tissue can be traumatized and infected by burns or from trauma resulting chewing on sharp bones, sticks or other sharp objects. Another cause of oral tissue trauma is from bite wounds. Some dogs sustain bites in the mouth from fights with other animals.
  • Foreign material. Bone or hair can become caught in the mouth causing a foul odor. This is a common reason for fishy smelling breath.
  • Oral tumors.  Tumors in the mouth can become infected or parts of the tumor can begin to die which can lead to a foul odor.
  • Digestive problems.  Some dogs with stomach or digestive problems can have bad breath.  Dogs that vomit often have foul smelling breath.

Other Causes of Bad Breath in Dogs

  • Lung cancer. Cancer of the throat, mouth, lungs, and nose can cause foul breath.
  • Respiratory infections. Various infections of the respiratory tract can cause foul smelling breath. It can be especially noticeable during exhalation or coughing.
  • Kidney disease. A decline in kidney function can cause some dog’s breath to have the odor of ammonia.
  • Diabetes. Another disease that can cause an abnormal oral odor is diabetes. A severe form of uncontrolled diabetes, diabetic ketoacidosis, can cause an abnormal sweet fruity odor.

How to Make Fishing Smelling Breath Go Away

The best way to make bad breath go way in your dog is to identify and treat the underlying problem that is causing the bad breath. You can sometimes identify the cause of your dog’s bad breath by the following:

  • Has your dog eaten anything abnormal such as compost? A dead animal carcass?  Got into the litter box? Trash?
  • Is your dog showing any signs of respiratory symptoms such as coughing or trouble breathing? Sneezing? Bloody nose?
  • Is your dog showing any signs of diabetes such as drinking more or urinating more?
  • Is your dog vomiting? Not eating? Losing weight?
  • Does your dog have signs of dental disease? Look in your dog’s mouth if you can do so safely. If you carefully lift up your dog’s lip, you can sometimes see red inflamed gums and tartar build-up on the teeth.  Many times the worst teeth and odor problems occur in the back of the mouth. If possible, look at the top teeth in the very back of the mouth for signs of redness, inflammation, and tartar build-up. In addition to bad breath, tartar build-up, redness, and/or swollen gums are all signs of problems.

If you notice any abnormalities in your dog, please see your veterinarian. Many of the dental problems can be very painful. If you don’t notice any problems but are still worried about your dog’s bad breath, make an appointment and allow your veterinarian to examine your dog and evaluate for possible underlying problems.

Products That Can Help Bad Breath in Dogs

There are many products on the market that can help bad breath in dogs.  The effectiveness largely depends on the underlying cause for bad breath. If your dog has a bad tooth or oral infection, no product will mask that smell without treating the infection or bad tooth.  Learn more about Home Remedies for Your Dog’s Bad Breath or  Tips to Cure Your Dog’s Bad Breath.

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