Why does my dog have bad breath?

Bad breath in dogs, also known as halitosis, is a common complaint among pet owners and can range from mildly unpleasant to downright offensive. While it might be tempting to dismiss it as normal "dog breath," persistent foul odor from your dog’s mouth is often a sign that something more serious is going on.

The most common culprit behind bad breath is dental disease. Just like in humans, bacteria accumulate in your dog’s mouth, especially along the gumline, leading to plaque and tartar buildup. Over time, this can cause inflammation of the gums (gingivitis), infection, and even periodontal disease. As the condition worsens, the bacteria release volatile sulfur compounds that produce the rotten smell.

Another reason your dog might have bad breath is the presence of foreign objects or food stuck between the teeth or under the gums, which can rot and emit foul odors. Dogs that chew on bones, sticks, or toys may develop tiny cuts or gum irritation that also harbor bacteria. Sometimes, the problem goes beyond the mouth.

Bad breath can be a symptom of systemic issues such as kidney disease, where waste products build up in the body and are expelled through the lungs, resulting in a urine-like smell. Similarly, diabetes can cause a sweet, fruity odor in the breath, especially if the disease is poorly controlled. Liver disease may also be a cause, often accompanied by yellowing of the eyes or gums and vomiting.

Diet plays a role as well. Dogs that eat feces, garbage, or other decaying materials may develop temporary bad breath due to what they’ve consumed. This behavior, known as coprophagia, is not only unpleasant but can expose dogs to harmful bacteria or parasites. Lastly, oral tumors or abscesses in the mouth, though less common, can also emit a strong, foul odor and should be evaluated by a veterinarian immediately.

In any case, persistent bad breath should never be ignored. Regular dental care, including tooth brushing, dental chews, and professional cleanings, can help prevent many causes of halitosis. However, if the smell is sudden, severe, or accompanied by other signs of illness, it’s crucial to consult a veterinarian for a thorough examination and diagnosis.

References Harvey, C. E. (2005). Periodontal disease in dogs: Etiopathogenesis and treatment.

Compendium on Continuing Education for the Practicing Veterinarian, 27(1), 21–34.Lobprise, H. B. (2007). Veterinary Dentistry for the Small Animal Technician. Wiley-Blackwell.