The oral microbiome in dogs and cats: biofilm, balance and breath

What the oral microbiome is

“Microbiome” means the whole community of microorganisms living in one place, together with their genes and what they do. The mouth is a busy habitat: mostly bacteria, alongside other microbes, living on the teeth, the gums, the tongue and the cheeks.

A healthy mouth is not a sterile one. Most of these microbes are commensals, residents that live alongside the gums without trouble and occupy space that less welcome species might otherwise use. Dogs and cats each carry their own community, distinct from each other's and from ours C.

Plaque is a biofilm, not dirt

Soon after the teeth are cleaned, a thin film of proteins from saliva coats them again. Bacteria attach to that film, multiply and surround themselves with a sticky matrix of their own making. The result is a biofilm: a structured, layered community that we see as plaque.

Three properties of biofilm explain daily oral care. It clings, so rinsing and licking do not remove it; it has to be physically disturbed by a brush, a finger brush or a textured wipe. It matures: left alone, a thin film thickens and changes, particularly along and just under the gumline, where oxygen is scarce. And it hardens: in the alkaline mouths of dogs and cats (saliva at around pH 7.5 to 8.5), minerals settle readily into plaque. Tartar's rough surface then gives new plaque a foothold, and no brush will lift it.

From balance to dysbiosis

When plaque is left to mature, the low-oxygen pocket between gum and tooth favours microbes that thrive without oxygen, and the balance of the whole community shifts. Researchers call this dysbiosis.

In dogs, published studies describe it in some detail. As gums become unhealthy, groups such as Porphyromonas (notably Porphyromonas gulae), Prevotella, Treponema, Tannerella and Fusobacterium become more abundant, and the commensal-dominated community recedes C. In cats, the community also differs between healthy mouths and mouths with common conditions, although far fewer studies have been done C.

Two points matter for pet parents. First, this is a community effect: gum disease in dogs is described as polymicrobial, and the relative balance of groups matters more than the presence of any single one. Second, these are associations. Whether the shift mainly drives gum changes, follows them, or both, is still being worked out.

What shapes the community

• Daily mechanical cleaning. The part of home care on the firmest footing. Brushing or wiping along the gumline disturbs biofilm before it matures or hardens, which keeps the community young and settled. It is Step 1 of the Petdentist Daily System for a reason.
• Professional cleaning. A veterinary dental clean under anaesthesia removes tartar and plaque above and below the gumline, where home care cannot reach. The American Animal Hospital Association's 2019 dental guidelines call anaesthesia-free cleaning “not appropriate”, partly because it cannot clean below the gumline of an awake animal.
• Diet and chewing. Ordinary kibble and most chews reach the gumline least, so neither replaces cleaning. Some chews have been tested for plaque or tartar and appear on the Veterinary Oral Health Council's accepted list; that acceptance belongs to those exact products.
• Age, size and breed. Royal Veterinary College VetCompass studies found periodontal disease diagnosed more often in older dogs and cats, in dogs under 15 kg and in certain breeds, so the same routine matters more for some pets than others.
• Complementary feeds. Dental powders and probiotics are designed to support the routine from another direction. Their evidence is specific to each ingredient, strain and product: see dental probiotics, decoded.

Why dogs and cats differ

It is tempting to think of a cat's mouth as a small dog's. The evidence says otherwise.

Our rule follows: cat evidence for cats, dog evidence for dogs, and nothing borrowed from people.

What “supporting a balanced oral environment” means

You will see this phrase on our products and on many others. Here is exactly what it does and does not mean.

If a product promises more than this about the microbiome, ask to see the evidence for that exact product, in that species.

Open research questions

• What does a healthy oral community look like for an individual dog or cat, and how much does it vary with breed, age and diet?
• Does the shift towards dysbiosis mainly drive gum changes, follow them, or both?
• Can anything change the community in a way that lasts once it is stopped? A 2026 review of microbe-based approaches in dogs noted that introduced microbes tend to persist only briefly, and that veterinary clinical evidence is still limited.
• How much does a microbiome product add for a pet whose teeth are cleaned every day?
• Which measurements matter? Oral-microbiome tests for dogs and cats are now offered commercially; which results should change everyday care is an open question.
• What applies to horses and camels? We have not yet reviewed their oral-microbiome research, and we assume nothing from dogs or cats.

Biodontic™, our science division, adds new studies to the research library as they are read and graded.

Putting it to work at home

1. Clean along the gumline every day. A soft brush, finger brush or textured wipe, for about a minute. Little and often beats occasional and thorough. Dogs · Cats
2. Use products made for the species. Labelled for dogs or for cats, with a serving for that species.
3. Lift the lip once a week. Pink gums, a clean gumline and neutral breath. Note anything new.
4. Keep the veterinary check. At least once a year: only a vet can look below the gumline.
5. Be sceptical of germ-free promises. A balanced mouth is the goal.