CONDITION
Periodontal Disease
Periodontal disease describes the progressive damage to the structures that hold teeth in place: the gums, the ligament that anchors each tooth, and the bone of the jaw itself. It begins with plaque, a soft film of bacteria that re-forms on a cleaned tooth surface within about a day. If plaque is not removed, it mineralises into tartar, and the bacteria beneath trigger inflammation that can eventually erode bone and loosen teeth. Many owners first notice a change in breath odour, reluctance to eat hard food, or a visible brown crust along the gum line. Some dogs and cats show no outward sign at all, even when disease beneath the gum is well established. The condition is extremely common, with most dogs and cats showing some degree of periodontal change by two years of age, but the rate of progression and the severity vary widely between individuals. This page explores what periodontal disease looks like from the outside, what is happening beneath the gum line, how the extent of damage is assessed, and the range of approaches used to slow progression or manage established disease. It also covers the role of home care, professional cleaning under anaesthesia, and the products that have been evaluated by the Veterinary Oral Health Council for their effect on plaque and tartar.
Why this matters now
A widely quoted figure is that about 80% of dogs and 70% of cats have some form of periodontal disease by two years of age, making it one of the most prevalent health conditions in companion animals. The condition develops progressively, often beginning silently in young adulthood and advancing throughout life. Toy and small-breed dogs, in which the teeth are relatively large for the size of the jaw and crowding is common, often show earlier or more severe involvement; flat-faced (brachycephalic) breeds with crowded teeth can be similarly affected.
The condition typically begins with plaque accumulation along the gum line, progressing to tartar formation, gum inflammation (gingivitis), and eventually periodontitis, the stage in which the supporting structures of the teeth are damaged. As the disease advances, bone loss around tooth roots can occur, potentially leading to tooth loosening or loss. Bacteria from the mouth may enter the bloodstream, with research suggesting possible associations with heart, kidney, and liver health.
Signals & patterns
Early signals
Mild bad breath
A subtle change in breath odour often represents the earliest noticeable sign, as bacterial populations in the mouth begin to increase. At this stage the smell is often only apparent during close contact, such as stroking or play, rather than being noticeable from a distance.
Slightly reddened gum margins
A thin red line along the gum edge, particularly around the back teeth, may indicate early gingivitis. The gum in this area can bleed slightly if touched or during chewing on harder foods, though this is easy to miss without deliberately looking inside the mouth.
Visible yellowish deposits on teeth
Tartar accumulation typically begins on the outer surfaces of the upper back teeth and canines, appearing as a yellowish-brown crust along the gum line. It tends to build up more readily on teeth that receive less mechanical cleaning from chewing.
Later signals
Strong, unpleasant breath odour
Advanced periodontal disease produces a characteristic foul smell from bacterial activity and tissue breakdown. The odour is usually noticeable without close contact and tends to persist despite routine cleaning around the mouth.
Reluctance to eat or preference for softer foods
Pain when chewing may lead to changes in eating behaviour, though many pets continue eating despite significant dental disease. Some animals chew on one side of the mouth, drop food, or take noticeably longer over meals than previously.
Visibly receding gums or exposed tooth roots
Loss of supporting tissue causes gums to pull back from teeth, sometimes revealing root surfaces that appear a different colour from the white enamel above the gum line. The exposed root surface can also become sensitive.
Loose teeth or changes in bite alignment
Bone loss around roots can cause teeth to become mobile or shift position, and an affected tooth may eventually fall out or need to be removed. Mobile teeth are often, though not always, associated with discomfort.
Facial swelling or a draining wound below the eye
A tooth-root abscess, most often involving the upper fourth premolar, can cause swelling of the face or a wound that opens and drains beneath the eye. This reflects infection tracking from the tooth root to the skin surface. Severe periodontal disease can reach the root tip and infect the tooth in this way, though the same swelling also arises from a tooth damaged by fracture or other trauma.
One-sided nasal discharge or sneezing
When periodontal disease around an upper canine tooth progresses far enough, it can create a small communication between the mouth and the nasal cavity known as an oronasal fistula, which may show as discharge or sneezing from one nostril. This pattern is described most often in older small-breed dogs, dachshunds in particular, though it can occur in any breed and in cats.
Sudden jaw fracture during normal activity
In small and toy breed dogs, prolonged bone loss around the roots of the lower jaw can weaken the mandible enough that it fractures during ordinary activities such as chewing or a minor knock, without an obvious traumatic cause. This reflects how far periodontal bone loss can progress before outward signs become apparent.
Click to read about the biological mechanisms
How this is usually investigated
Diagnosis typically begins with a visual assessment of the mouth, looking at gum colour, tartar deposits, and any obvious swelling or recession. A dental assessment under general anaesthesia allows closer examination of individual teeth, measurement of pocket depths around each tooth, and visualisation of areas hidden by the tongue or cheeks. Full-mouth dental radiographs are a standard part of this assessment, since a large proportion of bone loss in periodontal disease occurs beneath the gum line and cannot be judged from the visible crown alone. Where a swelling, mass, or area of bone change looks unusual for straightforward periodontal disease, biopsy helps distinguish it from an oral tumour such as oral melanoma, squamous cell carcinoma, or acanthomatous ameloblastoma (a locally invasive but non-spreading tumour arising from tooth-forming tissue), each of which can resemble advanced dental disease on initial examination.
Physical examination
Dental assessment
Radiography
Haematology
Biochemistry profile
Options & trade-offs
Management usually combines approaches aimed at removing existing bacterial load, reducing ongoing accumulation, and addressing discomfort or infection. The combination that proves workable varies with the severity of disease, the temperament and health of the individual animal, and what an owner can sustain over time. Different households find different strategies more or less practical.
Professional dental cleaning and treatment
Scaling removes tartar from tooth surfaces and beneath the gum line, followed by polishing to smooth enamel. Diseased teeth may be extracted if bone loss or mobility makes retention unviable. The procedure is performed under general anaesthesia to allow thorough cleaning and assessment of all surfaces.
Trade-offs: Anaesthesia carries inherent risks, particularly in older animals or those with heart, kidney, or other systemic conditions, though these can often be managed with appropriate monitoring and protocol adjustments. The procedure addresses existing disease but does not prevent recurrence without ongoing home care or other preventive measures.
Home oral hygiene
Daily tooth brushing with a soft brush and veterinary toothpaste can reduce plaque accumulation before it mineralises into tartar. The focus is on the gum line where bacteria tend to collect. Success depends on the animal's tolerance and the owner's ability to maintain a routine.
Trade-offs: Many cats and some dogs do not tolerate brushing, and attempts to introduce it can create stress or damage the bond between owner and pet if not approached gradually. Even with diligent brushing, some individuals develop tartar more readily than others, and brushing alone may not prevent disease in animals with advanced or rapidly progressing involvement.
Dental diets and water additives
Specially formulated dental diets have a texture or coating designed to reduce plaque or tartar as the animal chews. Water additives contain compounds intended to alter the oral environment or interfere with plaque formation. Some products carry Veterinary Oral Health Council (VOHC) acceptance, indicating they have been shown in controlled trials to reduce plaque or tartar.
Trade-offs: The degree of effect varies between products and individuals, and these approaches typically work alongside rather than replacing other measures. Switching diet may not be suitable for animals with specific nutritional needs, food sensitivities, or strong preferences, and some pets dislike the taste of water additives.
Dental chews and toys
Chew items with specific textures or shapes can provide mechanical cleaning as the animal gnaws, potentially reducing plaque on chewing surfaces. Products with VOHC acceptance have demonstrated measurable effects in controlled studies.
Trade-offs: The benefit depends on how much and how the animal chews, and some dogs or cats show little interest or swallow pieces without prolonged chewing. Hard chews carry a risk of tooth fracture, particularly in animals with weakened or already compromised teeth, and supervision is often warranted.
Antibiotics and anti-inflammatory medication
Antibiotics may be used when there is evidence of active infection, such as a tooth root abscess or severe gingival inflammation with discharge. Anti-inflammatory drugs can reduce pain and swelling in the short term, particularly around procedures or when extractions have been performed.
Trade-offs: These medications address symptoms or secondary infection but do not remove the underlying bacterial load or reverse structural damage such as bone loss. Long-term or repeated antibiotic use can contribute to resistance, and anti-inflammatory drugs carry their own side-effect profile, particularly with prolonged use or in animals with kidney or gastrointestinal sensitivities.
Common misconceptions
"Bad breath is normal in older dogs and cats and does not indicate a health problem."
Whilst many older animals do have noticeable breath odour, this typically reflects bacterial activity associated with periodontal disease rather than an inevitable aspect of ageing. The odour often signals ongoing inflammation and infection that may warrant investigation and treatment.
"If a dog or cat is still eating normally, their teeth must be fine."
Many animals continue to eat despite significant periodontal disease, fractured teeth, or oral pain. Dogs and cats often adapt their chewing behaviour, swallow food with minimal chewing, or preferentially use one side of the mouth. A normal appetite does not rule out the presence of painful or progressing dental disease.
"Once tartar is removed, the teeth will stay clean without further intervention."
Professional cleaning removes existing tartar and treats diseased tissue, but plaque forms again within about a day. Without ongoing home care, dietary measures, or other preventive strategies, tartar typically reaccumulates, and the disease process can resume. The interval before repeat cleaning is needed varies widely between individuals.
Related conditions
Tooth Resorption
Tooth resorption and periodontal disease can both affect the same tooth at different points, and severe periodontal disease may sometimes mimic or mask early resorptive lesions. Both conditions involve progressive damage beneath the gum line that may not be fully visible on the surface.
Stomatitis in Cats
Stomatitis and periodontal disease both involve chronic inflammation affecting the gums and other structures in the mouth, though stomatitis tends to be more widespread and severe. In some cats, periodontal disease may coexist with or contribute to the inflammatory burden seen in stomatitis.
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Oral Squamous Cell Carcinoma in Cats
Oral squamous cell carcinoma can present with visible changes to the gums or jaw that may initially be mistaken for advanced periodontal disease, particularly when there is bone involvement or tooth loosening. Both conditions can cause similar outward signs, and in some cases they may be present together.
Endocarditis
Bacteria from periodontal disease can enter the bloodstream through inflamed or damaged gum tissue, and in some cases this may seed infection on the heart valves, contributing to endocarditis. The relationship reflects a pathway rather than a certainty, and many other sources of bacteraemia exist.
Hepatic Lipidosis in Cats
Cats with severe periodontal disease may experience enough oral discomfort to reduce their food intake, and in some cases this reduced appetite can contribute to the cascade that leads to hepatic lipidosis. The connection is indirect and depends on other factors, including the cat's body condition and underlying health.
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Oral Melanoma
Oral melanoma can cause a pigmented or unpigmented mass, loose teeth, or bleeding from the gums that may initially resemble advanced periodontal disease, particularly before the mass is clearly distinct from the surrounding tissue. Biopsy distinguishes the two, and the distinction matters because oral melanoma in dogs tends to behave aggressively and can spread early.
Squamous Cell Carcinoma
Squamous cell carcinoma arising in the mouth can cause gum swelling, tooth loosening, and bone loss that closely resembles severe periodontal disease on visual examination, and dental radiographs or biopsy may be needed to tell the two apart. This distinction matters because a tumour will not respond to periodontal treatment alone.
Periodontal disease can progress substantially beneath the gum line before it becomes visible from the outside, which is why an assessment under anaesthesia often reveals more advanced disease than a conscious mouth check would suggest. A firm facial swelling, a persistent one-sided nasal discharge, or a lump on the gum can each reflect either ordinary periodontal disease or a tumour growing in a similar location, and these cannot reliably be told apart without dental radiographs or a tissue sample. Tracking changes in breath, chewing behaviour, and visible tartar over time, alongside the pattern and timing of any professional cleaning, can help build a picture of how the disease is progressing in an individual animal.
Last reviewed: 9 October 2026 · Dr Alastair Greenway MRCVS