Why Does My Dog’s Breath Smell Like Fish?

What Causes Fishy Breath in Dogs?

It can be quite alarming when your beloved furry friend has breath that smells like fish. However, there can be several reasons behind this unusual odor. Just like humans, dogs can also experience dental problems, gastrointestinal issues, or other health conditions that can lead to foul-smelling breath. Understanding the potential causes can help you determine the best course of action to address this issue and ensure your dog’s overall health and well-being.

1. Dental Problems

Poor dental hygiene is one of the most common causes of fishy breath in dogs. When dogs don’t receive regular dental care, bacteria can build up in their mouths, leading to various dental issues such as gum disease, tooth decay, and infections. These dental problems can cause an unpleasant odor, similar to that of fish. Additionally, if your dog has an oral infection or an abscessed tooth, it can further contribute to the fishy smell.

  • Signs of dental problems in dogs:
  • Bad breath
  • Red, swollen, or bleeding gums
  • Visible tartar or plaque buildup on teeth
  • Loose or missing teeth
  • Pain or difficulty while eating

2. Gastrointestinal Issues

Another possible cause of fishy breath in dogs is gastrointestinal issues. If your dog has an upset stomach, indigestion, or other digestive problems, it can result in foul-smelling breath. When the digestive system is not functioning properly, it can lead to the production of volatile gases and odors that manifest as fishy breath. In some cases, certain foods or dietary indiscretion can also contribute to gastrointestinal issues and subsequent bad breath.

  • Signs of gastrointestinal issues in dogs:
  • Vomiting or regurgitation
  • Diarrhea or loose stools
  • Loss of appetite
  • Abdominal pain or discomfort
  • Excessive gas or bloating

3. Kidney Disease

Kidney disease is a serious health condition that can affect dogs, and one of its symptoms can be fishy breath. When the kidneys are not functioning properly, they may not be able to filter waste products effectively, resulting in a buildup of toxins in the body. These toxins can be released through the breath, causing it to have a fishy odor. If you suspect that your dog’s breath is related to kidney disease, it’s essential to consult your veterinarian for proper diagnosis and treatment.

4. Diabetes

Diabetes is another potential cause of fishy breath in dogs. When a dog has diabetes, their body is unable to regulate blood sugar levels effectively. This can lead to a condition called ketoacidosis, where the body starts breaking down fat for energy instead of glucose. The byproducts of this fat metabolism can cause a distinct odor, often described as fruity or fishy breath. If you notice a fishy smell along with other signs of diabetes in your dog, such as increased thirst and urination, weight loss, or lethargy, it’s crucial to seek veterinary attention.

5. Liver Disease

Liver disease can also contribute to fishy breath in dogs. When the liver is not functioning properly, it may not be able to process toxins efficiently, leading to a buildup of waste products in the body. These waste products can be excreted through the breath, causing an unpleasant odor. In addition to fishy breath, other signs of liver disease in dogs may include jaundice (yellowing of the skin and eyes), loss of appetite, vomiting, and changes in behavior or energy levels.

6. Respiratory Infections

Respiratory infections, such as sinusitis or bronchitis, can sometimes result in breath that smells like fish. These infections can cause mucus or pus to accumulate in the nasal passages or throat, leading to a foul odor. Additionally, certain bacteria or fungi associated with respiratory infections can produce volatile compounds that contribute to the fishy smell. If your dog has respiratory symptoms along with fishy breath, it’s important to consult your veterinarian for proper diagnosis and treatment.

7. Dietary Factors

Finally, certain dietary factors can also influence the odor of your dog’s breath. Some foods, especially fish-based diets or treats, can leave a fishy smell lingering in your dog’s mouth. Additionally, if your dog has a habit of eating feces (a behavior known as coprophagia), it can lead to foul-smelling breath. This is because the digestion of feces can produce volatile compounds that contribute to the odor. Ensuring a balanced and appropriate diet for your dog and discouraging coprophagia can help minimize any unwanted smells.

How to Address Fishy Breath in Dogs

If your dog’s breath smells like fish, it’s important to address the underlying cause rather than simply masking the odor. Here are some steps you can take to help improve your dog’s breath:

  • Maintain good dental hygiene: Regularly brush your dog’s teeth with a dog-specific toothpaste and provide dental chews or toys to help remove plaque and tartar.
  • Visit the veterinarian: Schedule a dental check-up for your dog and address any dental issues or health concerns detected during the examination.
  • Provide a balanced diet: Ensure your dog’s diet is nutritionally balanced and appropriate for their age, breed, and health condition.
  • Encourage hydration: Make sure your dog has access to fresh water at all times to prevent dehydration and promote overall oral health.
  • Monitor their eating habits: Supervise your dog’s eating habits to prevent them from ingesting inappropriate substances, such as feces or spoiled food.
  • Consider professional cleaning: In severe cases of dental disease, your veterinarian may recommend a professional dental cleaning under anesthesia.
  • Follow your veterinarian’s advice: If your dog’s fishy breath is due to an underlying health condition, follow your veterinarian’s recommended treatment plan and attend regular check-ups.


Q: Can certain medications cause fishy breath in dogs?

A: Yes, some medications can cause changes in a dog’s breath odor. If your dog is taking any medications, consult with your veterinarian to determine if they could be contributing to the fishy smell.

Q: Are there any home remedies to improve my dog’s breath?

A: While there are various home remedies suggested for improving a dog’s breath, it’s essential to address the underlying cause of the odor. Home remedies, such as adding parsley to their food or using breath freshening sprays, may provide temporary relief but won’t solve the underlying issue.

Q: How often should I brush my dog’s teeth?

A: Ideally, you should brush your dog’s teeth daily to maintain good oral hygiene. However, if daily brushing is not feasible, aim for at least two to three times per week.

Q: Can fishy breath in dogs be a sign of cancer?

A: While it’s rare, certain cancers, such as oral tumors or gastrointestinal cancers, can sometimes cause changes in breath odor. If you have concerns about your dog’s breath, it’s best to consult with your veterinarian for a proper diagnosis.

Q: Is it normal for a puppy’s breath to smell fishy?

A: A mild fishy smell in a puppy’s breath can be normal, especially if they have recently eaten fish-based food. However, if the odor is persistent or accompanied by other symptoms, it’s advisable to consult with a veterinarian to rule out any underlying issues.

Q: Can fishy breath in dogs be prevented?

A: While not all cases of fishy breath can be prevented, maintaining good dental hygiene, providing a balanced diet, and addressing any health concerns promptly can help reduce the likelihood of developing fishy breath in dogs.

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