Bad Breath in Cats

Cats pride themselves on their hygiene. Although it would be nice to think that their constant self-cleaning is performed for our benefit, their grooming actually serves a more instinctive purpose: to remove odors that would make them detectable to any predators or prey.

Being self-cleaning and odor-free is definitely a nice perk of cat ownership. While there are several reasons why a cat might not be so sweet-smelling, in my experience as a cat veterinarian, a malodorous mouth is the most common reason for a foul-smelling feline.

Causes of Bad Breath

Dental issues are the most frequent cause of feline halitosis (the technical term for bad breath).

The most common is periodontal disease, an inflammation of the tissues that surround the teeth, caused by the buildup of plaque and tartar. Plaque contains a lot of bacteria. These bacteria release sulfur compounds that smell pretty horrible. Treatment of periodontal disease requires professional removal of plaque and tartar at a veterinary office, followed by conscientious, regular home care.

Tooth root abscesses are common in cats. As the abscess grows in size, a swelling will usually become visible on the cat’s face, near the site of the affected tooth. Sometimes the infection breaks through the skin, and pus will drain onto the cat’s fur. More often, pus will drain around the tooth and into the cat’s mouth, causing bad breath (as you might imagine). Tooth root abscesses need to be lanced and drained by a veterinarian. In most cases, the affected tooth will need to be extracted, and the cat will need antibiotics for a few days.

Respiratory viruses are very common in cats. One of these viruses, the calicivirus, often causes ulceration of the tongue. These ulcers can cause a rank smell in the mouth. Fortunately, most cats quickly recover from these viral infections. The oral ulcer heals, and the smell goes away.

Sadly, oral tumors are a well-documented cause of feline halitosis, with squamous cell carcinoma being the most common. As the tumor grows, parts of it may become infected and begin to decay, resulting in an unpleasant smell. Most oral tumors in cats have a poor prognosis, because by the time the cat starts showing signs that there’s a problem in the mouth, the tumor has infiltrated too extensively and treatment isn’t possible.

Non-oral conditions can also be responsible for feline halitosis.

As cats age, their kidneys begin to weaken, and their ability to filter toxins from the bloodstream becomes impaired. As the dysfunction progresses, the toxin level in the bloodstream rises and cats can develop uremia, literally “urine in the blood.” Cats with uremia often have very foul breath. I’ve examined hundreds of cats with chronic kidney disease, and I can easily distinguish the distinct “rotting” stench of uremic breath from the less offensive (but still bad) smell of periodontal disease. Cats with uremia will often develop ulcers in their mouths (most notably on the sides of their tongues), and these ulcers contribute further to the bad breath.

Diabetes is another metabolic disorder that can affect a cat’s breath. Some diabetic cats will have a sweet smell to their breath. The smell isn’t necessarily bad, just different. The dramatic clinical signs of diabetes (increased thirst, increased urination, enhanced appetite, noticeable weight loss) are more likely to be noticed by a cat owner than the subtle, fruity-smelling breath that some diabetic cats exhibit. Still, any change in your cat’s breath (good or bad) warrants a look by your vet.

How to Treat

As with most medical issues, the ideal way to treat a problem is to prevent it. Because periodontal disease is the most common cause of feline halitosis, a dental home care regimen is recommended for cats. This means:

  1. Brush your cat’s teeth regularly
  2. Feed a diet designed to reduce plaque and tartar buildup
  3. Give your cat dental treats.

Note that not every case of halitosis portends something ominous. I have examined many cats brought to me because the owner found their cat’s breath distasteful. Upon examination, these cats have clean teeth, no oral infections or tumors and no systemic illnesses. My diagnosis in these cats is simply “tuna-breath.” Hey, if you feed your cat smelly food, don’t be too shocked if he has smelly breath!

Trying foods with different protein sources (say, chicken instead of seafood) may be all that’s needed to solve the problem. Still, it’s better to err on the side of caution and have your cat examined if he doesn’t pass the smell test, given the myriad medical conditions that can cause halitosis.


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