Cats Oral Health: myths & science

After having tackled obesity in cats—the second most common health issue—it’s time to talk about the first one: periodontal diseases. It’s estimated that around 70-80% of cats have some form of oral disease! In today’s article, we are going to see what we can do to prevent these diseases as pet owners, and the role of the diet in periodontal diseases.

Oral health: a few explanations

Periodontal disease refers to all diseases linked to the inflammation of the gum.
Let’s build up some vocabulary to better understand the two main periodontal diseases: gingivitis and periodontitis.
The plaque is the bacteria biofilm present on the teeth of our cats. If plaque is not removed, it can calcify in only two weeks and form calculus—also called tartar. The tartar is solid and hard to remove. It’s also always covered with a layer of plaque.
The bacteria of the plaque can penetrate the gum and that’s when your cat starts having gingivitis—an inflammation of the gums. Gingivitis is reversible: it can go away by removing the plaque. The bacteria of the plaque and the gums can also exist in a symbiotic relationship. In that case, the gingivitis doesn’t get worse.
It’s also important to note that the presence of tartar is a predisposing factor for gingivitis but it is not necessarily a cause of gingivitis. In fact, a cat can have severe gingivitis without calculus and vice versa.
The gingivitis can, however, progress into periodontitis. In this case, it starts affecting the tissues supporting the teeth and causes bone loss and tooth loss. Periodontitis can only be diagnosed reliably under general anesthesia with probing and dental radiography.
While some nefarious consequences of bad oral health are obvious (losing teeth), others are less known: cardiovascular diseases, kidney diseases, chronic respiratory diseases, and diabetes. One of the reasons periodontitis can affect not only the mouth but the whole body might be that it is an entry door for the bacteria of the plaque to go into the body via the bloodstream. [11][15][19][20]

An important part of periodontal disease prevention is then the control of the plaque, more than controlling the tartar, which is mainly cosmetic.
Overall, periodontal diseases are painful and can affect the quality of life of your cat, as well as reduce its longevity. [26]

Kibbles don’t clean teeth

One of the biggest myths about kibbles is that they clean the teeth of our pets. While it’s true that kibbles can have an abrasive effect (especially when compared to wet food), it doesn’t mean that they remove the plaque or the tartar. Most kibbles will, in fact, just crumble and won’t offer enough resistance to the teeth to have any meaningful effect and that’s if your cat doesn’t just swallow the kibbles whole. [9][10]
Considering the number of domestic pets having periodontal disease and calculus, it’s not really a surprise that kibble isn’t that helpful when considering teeth health.
At best, some kibbles (which are VOHC-approved) with specific shapes, sizes, and textures have proved to reduce plaque or tartar accumulation. This doesn’t mean that it reduces the plaque or tartar on the teeth, but it reduces the rate at which new plaque gets on the teeth.
Given the many cons of kibbles concerning your cat’s health such as the lack of moisture, if you are looking to improve the oral health of your cat there are better alternatives, as we will see in the next paragraphs.

Raw meaty bones work (but they don’t make miracles)

It’s quite easy to understand that raw meaty bones offer an abrasive effect as they are much harder than the typical commercial pet food. A few studies compared the teeth health of feral cats with the ones of domestic cats to see if a diet containing bones would have an impact on it. The oldest study reported significantly less tartar on the teeth and a bit less incidence of periodontal disease for feral cats than domestic cats. [3]
The second study on feral cats also reported significantly less tartar, but the same incidence of periodontal disease. [4]
Both studies on cats are quite old and have methodological flaws, but it seems clear that a diet containing bones can at least reduce calculus.

However, we do have a bit more studies on big felids.
The first one was done in 1984 on captive tigers and it showed that giving them beef bones to chew on twice a week reduced plaque and calculus with no negative consequences. [1]
In 2016, a retrospective compared the oral health of captive felines that eat a minced meat diet versus wild ones that eat whole carcasses. The wild felines had better oral health, with less plaque, calculus, gingivitis, and periodontitis. Not only that, but it also seems that bad oral health is correlated with increased cranial deformations. [2][12][17]
The study concluded that the mechanical properties of the diet are essential: eating bones, tendons, and skin (like wild felines do) is very important. As cats are small felines, these results also apply to them, taking into account that appropriately sized bones must be fed.

The effect of bone on plaque and tartar has also been shown in studies on dogs. It’s also interesting to note that feeding bones came with no negative consequences such as teeth fractures, pieces of bone stuck between teeth, or intestinal obstructions.  [18]
In wild animals such as wolves, tooth fractures increase when there is a lack of prey, as the wolves—in that case—eat bones that they wouldn’t normally eat. It seems that in normal conditions, tooth fractures due to bones are quite low. [16]
This is also in agreement with the studies on dogs where the authors mentioned that accidents with bones are related to the type and size of the bones consumed.
As in a raw diet, the bones which are considered edible are specific and adapted to the size of the cat: they don’t pose any particular risk.

Finally, another word of caution on raw meaty bones. In most studies, cats and large felids (wild or not) very often had tartar on the last molars. This is mainly due to the shape of their mouth. So, while raw meaty bones can be efficient, they aren't a miraculous solution, especially concerning the molars of cats.

VOHC-approved products

You may have heard about VOHC products marketed to help the oral health of your cat. Some treats, water additives, and oral gels are accepted by the Veterinary Oral Health Council. This means that these products proved in at least a study that they reduce plaque or tartar accumulation. As for kibbles, this doesn’t mean that they reduce the plaque or tartar on the teeth, but it means that your cat will get less new plaque or tartar than if they didn’t use this product. Note that the VOHC doesn’t publish any studies: it’s up to the manufacturers to make and publish them according to the VOHC standards, which can create conflicts of interest. [11][5][6]

So, don’t expect your cat to magically get clean teeth when using VOHC-approved products! While these products can be useful to maintain good oral health after professional teeth scaling and cleaning, they are not a substitute for them as they won’t remove the plaque or tartar.

Ascophyllum Nodosum

Products based on Ascophyllum Nodosum (an alga which is often called kelp) such as PlaqueOff seem to be effective to reduce plaque and tartar accumulation. However, the studies on cats are unpublished and done by the manufacturers, so we don’t know what is the minimum, needed dosage to have an actual effect. [22][23]
If you follow the dosage recommendation mentioned on the packaging, the supplement provides 264 mcg of iodine. This is concerning because the daily iodine requirement for a 4 kg cat is only 32 mcg (i.e. PlaqueOff would provide 8 times the daily requirement of iodine). Excess iodine can cause hyperthyroidism, as we discussed in this article.

Water additives containing xylitol

Water containing xylitol seems to be effective to reduce plaque and tartar accumulation. However, I want to mention that I don’t recommend this kind of product. While a study has shown water additives to be safe, high doses of xylitol are toxic to cats and their effects in the long term are not known.

Finally, as cats don’t drink a lot of water (particularly if your cat is fed a wet diet), the interest in these products is limited.

Chlorhexidine

Chlorhexidine gluconate (0.12% dilution)—when added to toothpaste or oral gels—has proven to be effective as an anti-microbial and can help reduce inflammation in case of gingivitis and plaque accumulation. However, the taste of chlorhexidine is reported as unpleasant and long-term use may stain the teeth. [11][15]

Zinc

Soluble zinc salts—such as zinc ascorbate or zinc gluconate—are often present in oral gels, dental chews, and toothpaste. They help to control plaque accumulation because of their antimicrobial activity. They also seem to reduce bad breath. [11][15]

Natural alternatives

Some natural plants have proven to be efficient for their antimicrobial or antiplaque properties in humans, but most of the time they aren’t proven to be efficient or safe for pets.

Aloe vera gel (note that the gel of the aloe vera is safe for pets, while the plant in itself can be toxic!) seems to be very promising as it has proven to be as efficient as chlorhexidine in reducing plaque accumulation on the teeth. [25]

While not studied for oral health, Matatabi (also called Silver Vine) sticks may be interesting for cats. In fact, this plant has a euphoric effect similar to the one of catnip, for 80% of cats. Some cats tend to chew the sticks which may potentially have an abrasive effect. In case it doesn’t have oral health benefits, it’s still a safe way to provide an olfactory enrichment. [24]

The best solution: brushing your cat’s teeth

The gold standard in pets and human oral health remains teeth brushing. In fact, regular teeth brushing removes the plaque, which prevents gingivitis. To be effective, teeth brushing needs to be done regularly, at least once every week, even if the best would be every day.
Not all cats will accept having their teeth brushed: that’s why it’s important to start doing it when they are kittens, even if they don’t have any sign of oral disease yet. Even if your cat is older, not everything is lost as you can still teach them using positive reinforcement and cooperative care. You can find on this website some resources on how to do it. [7][8][15]

For the toothpaste, never use human toothpaste as it contains fluoride and foaming agents which are dangerous for our pets. It’s not primordial to use toothpaste as the most important part of teeth brushing is the mechanical action. However, finding toothpaste with a taste that your cat likes can help to make it a more pleasant moment. Some toothpaste contains enzymes, zinc, abrasive particles, or other components that may help reduce plaque.

Next steps in research: the microbiome

Currently, new research focuses on the oral microbiome. In fact, plaque is an accumulation of bacteria. Some of these bacteria can coexist symbiotically with gingivitis, while others cause infections. Research has shown that diet and nutrients can influence the microbiome of the mouth, but it’s unclear at the moment which diet promotes a healthy or nefarious microbiome. [13][14][15][21][27]
In the future, we will probably know more about which factors create a healthy microbiome, with research on probiotics and prebiotics for the oral microbiome.

To conclude, periodontal diseases are a true concern as they are painful for our cats and impact their quality of life as well as longevity. The main cause of gingivitis is the accumulation of plaque, while the accumulation of tartar is more of an aesthetic concern.
The gold standard for oral health is teeth brushing, and regular professional teeth cleaning! While not all cats tolerate teeth brushing, through cooperative care and with patience you can create a ritual that your cat will accept.
Many products claim to clean the teeth of our cats, but most of the time they have been evaluated only to see if they slow down the accumulation of plaque and tartar. 
It seems that only mechanical and abrasive methods can actually remove the plaque or tartar.
Raw meaty bones have proven to be efficient for wild carnivores and should be efficient to (at least) remove some tartar in cats.
Finally, it’s a myth that kibbles can clean teeth, as they don’t have enough abrasive effect to do so.

Sources

[1] Haberstroh, L. I., Ullrey, D. E., Sikarski, J. G., Richter, N. A., Colmery, B. H., & Myers, T. D. (1984). Diet and Oral Health in Captive Amur Tigers (Panthera tigris altaica). The Journal of Zoo Animal Medicine, 15(4), 142.
[2] Bond, J. C., & Lindburg, D. G. (1990). Carcass feeding of captive cheetahs (Acinonyx jubatus): the effects of a naturalistic feeding program on oral health and psychological well-being. Applied Animal Behaviour Science, 26(4), 373–382.
[3] Verstraete, F. J., van Aarde, R. J., Nieuwoudt, B. A., Mauer, E., & Kass, P. H. (1996). The dental pathology of feral cats on Marion Island, part II: periodontitis, external odontoclastic resorption lesions and mandibular thickening. Journal of comparative pathology, 115(3), 283–297.
[4] Clarke, D. E., & Cameron, A. (1998). Relationship between diet, dental calculus and periodontal disease in domestic and feral cats in Australia. Australian veterinary journal, 76(10), 690–693.
[5] Gorrel, C., Inskeep, G., & Inskeep, T. (1998). Benefits of a ‘Dental Hygiene Chew’ on the Periodontal Health of Cats. Journal of Veterinary Dentistry, 15(3), 135–138.
[6] Ingham KE, Gorrel C, Bierer TL. Effect of a dental chew on dental substrates and gingivitis in cats [published correction appears in J Vet Dent. 2003 Sep;20(3):136]. J Vet Dent. 2002;19(4):201-204.
[7] Ingham KE, Gorrel C, Blackburn JM, Farnsworth W. The effect of toothbrushing on periodontal disease in cats. J Nutr. 2002;132(6 Suppl 2):1740S-1S.
[8] Ray JD Jr, Eubanks DL. Dental homecare: teaching your clients to care for their pet's teeth. J Vet Dent. 2009;26(1):57-60.
[9] Clarke, D.E., Servet, E., Hendriks, W.H., Thomas, D.G., Weidgraaf, K., & Biourge, V.C. (2010). Effect of Kibble Size, Shape, and Additives on Plaque in Cats. Journal of Veterinary Dentistry, 27, 84 - 89.
[10] Mata F. (2015). The Choice of Diet Affects the Oral Health of the Domestic Cat. Animals : an open access journal from MDPI, 5(1), 101–109.
[11] Perry R, Tutt C. Periodontal disease in cats: back to basics--with an eye on the future. J Feline Med Surg. 2015;17(1):45-65.
[12] Kapoor V, Antonelli T, Parkinson JA, Hartstone-Rose A. Oral health correlates of captivity. Res Vet Sci. 2016 Aug;107:213-219.
[13] Adler CJ, Malik R, Browne GV, Norris JM. Diet may influence the oral microbiome composition in cats. Microbiome. 2016;4(1):23. Published 2016 Jun 9.
[14] Thengchaisri, N., Steiner, J. M., Suchodolski, J. S., & Sattasathuchana, P. (2017). Association of gingivitis with dental calculus thickness or dental calculus coverage and subgingival bacteria in feline leukemia virus- and feline immunodeficiency virus-negative cats. Canadian journal of veterinary research = Revue canadienne de recherche veterinaire, 81(1), 46–52.
[15] Bellows, J., Berg, M. L., Dennis, S., Harvey, R., Lobprise, H. B., Snyder, C. J., Stone, A., & Van de Wetering, A. G. (2019). 2019 AAHA Dental Care Guidelines for Dogs and Cats. Journal of the American Animal Hospital Association, 55(2), 49–69.
[16] Van Valkenburgh, B., Peterson, R. O., Smith, D. W., Stahler, D. R., & Vucetich, J. A. (2019). Tooth fracture frequency in gray wolves reflects prey availability. eLife, 8, e48628.
[17] Emslie, R. S., Zeiler, G., Loock, D., Boy, S. C., & Steenkamp, G. (2020). Dental Pathology in a Wild Serval (Leptailurus serval) Population. Journal of comparative pathology, 180, 16–28.
[18] Pinto CFD, Lehr W, Pignone VN, Chain CP, Trevizan L. Evaluation of teeth injuries in Beagle dogs caused by autoclaved beef bones used as a chewing item to remove dental calculus. PLoS One. 2020;15(2):e0228146. Published 2020 Feb 13.
[19] Hall, J. A., Forman, F. J., Bobe, G., Farace, G., & Yerramilli, M. (2021). The impact of periodontal disease and dental cleaning procedures on serum and urine kidney biomarkers in dogs and cats. PloS one, 16(7), e0255310.
[20] Oskarsson, K., Axelsson Puurtinen, L., & Penell, J. C. (2021). Dental Problems and Prophylactic Care in Cats-Knowledge and Perceptions among Swedish Cat Owners and Communication by Veterinary Care Staff. Animals : an open access journal from MDPI, 11(9), 2571.
[21] Rodrigues MX, Fiani N, Bicalho RC, Peralta S. Preliminary functional analysis of the subgingival microbiota of cats with periodontitis and feline chronic gingivostomatitis. Sci Rep. 2021;11(1):6896. Published 2021 Mar 25.
[22] Gawor J, Jank M, Jodkowska K, Klim E, Svensson UK. Effects of Edible Treats Containing Ascophyllum nodosum on the Oral Health of Dogs: A Double-Blind, Randomized, Placebo-Controlled Single-Center Study. Front Vet Sci. 2018;5:168. Published 2018 Jul 27.
[23] Gawor JP, Wilczak J, Svensson UK, Jank M. Influence of Dietary Supplementation With a Powder Containing A.N. ProDen™ (Ascophyllum Nodosum) Algae on Dog Saliva Metabolome. Front Vet Sci. 2021;8:681951. Published 2021 Jun 22.
[24] Bol, S., Caspers, J., Buckingham, L. et al. Responsiveness of cats (Felidae) to silver vine (Actinidia polygama), Tatarian honeysuckle (Lonicera tatarica), valerian (Valeriana officinalis) and catnip (Nepeta cataria). BMC Vet Res 13, 70 (2017).
[25] Sánchez, M., González-Burgos, E., Iglesias, I., & Gómez-Serranillos, M. P. (2020). Pharmacological Update Properties of Aloe Vera and its Major Active Constituents. Molecules (Basel, Switzerland), 25(6), 1324.
[26] Watanabe, R., Frank, D., & Steagall, P. V. (2020). Pain behaviors before and after treatment of oral disease in cats using video assessment: a prospective, blinded, randomized clinical trial. BMC veterinary research, 16(1), 100.
[27] Mäkinen, V. , Mäyrä, A. and Munukka, E. (2019) Improving the Health of Teeth in Cats and Dogs with Live Probiotic Bacteria. Journal of Cosmetics, Dermatological Sciences and Applications, 9, 275-283