Cat vs Dog. Who Has Cleaner Mouths?


The cleanliness of a pet’s mouth is an important health consideration for owners. With different anatomies and eating habits, cats and dogs each have their own oral hygiene needs. The question of which pet has a cleaner mouth has been frequently debated among vets and pet owners. This article will compare cats and dogs in terms of mouth anatomy, diet, bacteria levels, dental diseases, and home dental care to determine whether felines or canines tend to have better oral health.

Anatomy of Cat and Dog Mouths

Both cats and dogs belong to the order Carnivora and have specialized teeth and mouth anatomy for consuming an omnivorous diet (1). There are several similarities and key differences between cat and dog mouth anatomy. Cats have 30 adult teeth compared to 42 in dogs (2). The types of teeth are the same in both species – incisors, canines, premolars, and molars – but the numbers vary. For example, cats have 6 incisors on the top and bottom while dogs have between 6-8 incisors on top and 6 on bottom. Dogs have a total of 16 premolars and molars while cats only have 12 (3).

While cats and dogs have the same types of teeth, the size and shape is quite different. Dogs have much larger and pronounced canine teeth since they are generally used more for hunting and protection whereas house cats don’t require large canines (2). Canine teeth in cats are more needle-like for gripping prey while dogs have thicker cone-shaped canines. The incisors and molars of dogs are also considerably larger than in cats.

Both species have a set of deciduous (baby) teeth that fall out and are replaced by permanent adult teeth. The adult teeth eruption timeline occurs earlier in dogs, typically between 4-7 months of age versus 3-6 months in cats (4).

In terms of other anatomical structures, cats and dogs share the same overall mouth anatomy – lips, gums, palate, cheeks, tongue, and salivary glands. However, there are a few subtle differences. Dogs have larger, floppy lips compared to cats. Cats only have 3 types of salivary glands whereas dogs have more (4). Additionally, a cat’s tongue has small backward-facing barbs for grooming and lapping food while a dog’s tongue is smooth (5).

Overall, while cats and dogs share very similar mouth anatomy, dogs tend to have larger teeth and certain structures related to their historical role as hunters.



Dietary Habits

Cats and dogs have very different dietary requirements due to differences in their digestive systems. Cats are obligate carnivores, meaning they must eat meat to acquire certain essential nutrients. Cats require a high-protein, meat-based diet, as they cannot synthesize some essential amino acids like taurine on their own. Their bodies are adapted to metabolize protein and fat from animal tissues.

In contrast, dogs are omnivores with a more versatile digestive system. While dogs can thrive on a meat-based diet, they can also digest plant material and obtain nutrients from grains, fruits and vegetables. Their bodies produce the enzymes needed to break down carbohydrates as an energy source. However, the ideal dog diet should still contain a good portion of high-quality animal protein in addition to plant-based foods.

Tooth Brushing

Tooth brushing is an important part of caring for a pet’s oral health and cleanliness. Research shows that regular brushing works for dogs and cats the same way it does for humans – it helps prevent gum disease, removes plaque and bacteria, and keeps breath fresh.[1] However, surveys indicate that tooth brushing is much more common among dog owners compared to cat owners.

In a 2016 survey, 95% of pet owners reported brushing their own teeth daily, but only 8% brushed their dog’s teeth daily, and just 4% brushed their cat’s teeth daily.[2] Older pet owners were the least likely to brush their pet’s teeth. Another study in 2020 found that 71% of dog owners brushed their dog’s teeth, but only 29% considered it very important for their dog’s dental health.[3]

The infrequency of cat teeth brushing may be due to cats being more difficult to handle for tooth brushing. But regular brushing can greatly benefit cats as well. Overall, while tooth brushing is relatively common among dog owners, there is room for improvement, especially when it comes to cats.

Saliva Composition

Research shows that cat and dog saliva differ significantly in their composition. One key difference is the levels of antimicrobial enzymes. A study published in the Journal of Veterinary Behavior found that cat saliva contains potent antibacterial enzymes like lysozyme, peroxidase, xanthine oxidase, and nitrogen compounds like urea and ammonia. These enzymes work to kill bacteria and other microbes in the cat’s mouth (1).

In contrast, dog saliva has lower levels of these antimicrobial compounds. A paper in The Scientific World Journal showed dog saliva was deficient in lysozyme and lactoferrin compared to human saliva. This suggests dog saliva may allow more bacteria to thrive (2).

The antimicrobial properties of cat saliva likely contribute to cats having lower bacteria counts overall in their mouths compared to dogs. Cats also exhibit more fastidious grooming behaviors that spread saliva over their coats, reducing microbes. These enzymes in feline saliva help keep their oral bacteria in check.


Bacteria Counts

Studies comparing the oral bacteria in cats, dogs, and humans have found some notable differences. One study published in the Canadian Journal of Comparative Medicine found that human oral flora contained the smallest number of bacteria followed by dog and cat oral flora, respectively (Rayan, 1991). Another small study looked specifically at bacteria counts in the saliva and found dogs had the highest counts, followed by cats, and humans had the lowest (Gustafson, 2002). However, the sample sizes were very small in this study.

Overall, research indicates cats and dogs have a higher oral bacterial load compared to humans. One reason is their lack of routine oral hygiene practices that humans engage in, like brushing and flossing. Cats and dogs also eat foods and exhibit behaviors that allow more bacteria to accumulate, like eating raw meats and licking dirty surfaces. Their mouths may also harbor different types of bacteria compared to humans.

Dental Diseases

Dental diseases are very common in both cats and dogs. According to Today’s Veterinary Practice, by 2 years of age, 80% of dogs and 70% of cats have some form of periodontal disease. They also report that the incidence of periodontal disease of over 80% in the mature and geriatric dog population correlates with generally accepted feline figures.

Pet Care Rx states that most veterinarians agree that 75% or more of the health problems they see are related to dental disease in cats and dogs. Periodontal disease is so prevalent in pets because plaque and tartar buildup on the teeth creates an environment where bacteria can thrive and cause infections in the mouth.

Overall, studies show that the rates of dental diseases in dogs and cats are similarly very high. Proper dental care for pets is essential to prevent painful infections that could lead to tooth loss or systemic health issues if left untreated.

Bad Breath

When it comes to bad breath, also known as halitosis, dogs tend to have it worse than cats. According to research, around 80-90% of dogs over the age of 3 suffer from some level of halitosis, compared to only around 10% of cats [1]. The main cause of halitosis in both dogs and cats is periodontal disease. Food particles and bacteria accumulate on the teeth and gums, forming plaque and tartar that cause inflammation, gingivitis, and eventually tooth decay if not properly treated. However, dogs’ tendency to chew on objects more often than cats leads to higher rates of periodontal disease at a younger age.

Additionally, some dog breeds like Beagles and Bloodhounds have extra folds of skin around their mouths that trap bacteria and contribute to worse breath. Brachycephalic (short-nosed) breeds like Bulldogs, Boxers, and Pugs are also prone to more severe halitosis because their shortened airways allow oral bacteria to enter the lungs more easily.

Proper dental care like daily tooth brushing, dental chews, yearly cleanings at the vet, and a diet low in carbs and high in raw foods can help minimize bad breath in both cats and dogs. But overall, halitosis is more prevalent and severe in the canine population compared to felines.

Home Dental Care Tips

There are several things pet owners can do at home to help maintain good oral health for their cats and dogs. Here are some of the most effective home dental care tips:


Brushing your pet’s teeth regularly is the single most effective way to reduce plaque buildup and prevent dental diseases. Use a soft-bristled toothbrush and pet-safe toothpaste to gently brush along the outer surfaces of the teeth. Brushing should be done at least 2-3 times per week. Here’s a helpful video on proper brushing technique: Brushing Cat and Dog Teeth

Dental Treats

There are a variety of dental treats and chews available that are formulated to scrape plaque off teeth as your pet chews them. Offering dental treats 2-3 times a week helps control tartar buildup between brushings. Look for treats approved by the Veterinary Oral Health Council (VOHC).

Water Additives

Adding an oral rinse or gel to your pet’s water is an easy way to improve oral health daily. These products contain enzymes that break down plaque. Just add the recommended amount to your pet’s water bowl each time you fill it up.

With some simple dental care habits at home, you can significantly improve your pet’s oral hygiene and reduce the risk of dental disease.


After reviewing the available evidence, it appears that cats generally have cleaner mouths than dogs. Cats’ teeth anatomy and dietary habits lend themselves to less plaque buildup and dental disease. The structure of cats’ teeth helps scrape away debris, and their food is less likely to stick to teeth. Cats are also more fastidious groomers who regularly lick their mouths clean.

While dogs’ mouths tend to harbor more bacteria overall, individual dental care makes a big difference for both species. With regular tooth brushing, use of dental treats or chews, and professional cleanings, dogs can achieve excellent oral health. For cats, home dental care is challenging but can reduce plaque and tartar. Ultimately, regardless of species, the key to clean teeth and fresh breath lies in vigilant home dental care and professional veterinary cleanings.

In summary, evidence indicates cats generally have cleaner mouths than dogs when left to their own devices. But with diligent home dental care, dogs can achieve a very high level of oral cleanliness as well.

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