The Canine Ledger

Dental Disease in Dogs: What Brushing Can and Can't Do

Gum disease is the most common diagnosis in UK vet practices. What causes it, what brushing prevents, and what only a cleaning under anaesthesia can fix.

Written by thecanineledger

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In a study of more than 22,000 dogs seen at UK veterinary practices, “The 1-year period prevalence for diagnosis with periodontal disease was 12.52%” (O’Neill et al., J Small Anim Pract 2021). A companion study from the same records found it was the most common specific diagnosis of all, ahead of ear infections and obesity (O’Neill et al., BMC Vet Res 2021).

That figure counts only dogs whose vet recorded the diagnosis in that year. The real number with some gum disease is likely to be higher, because much of it is below the gumline, where an owner can’t see it.

While good home care can do a great deal, it can’t undo disease that is already there. This page explains what gum disease is, what brushing prevents, and why the part that matters most needs a cleaning under anaesthesia.

1. What periodontal disease is

Periodontal disease is disease of the tissues that hold a tooth in place: the gums, the bone and the ligament between them. It starts with plaque, a soft film of bacteria that forms on teeth every day.

The Merck Veterinary Manual, in a chapter written by a board-certified veterinary dentist, explains what happens if plaque is left alone: “Plaque that remains on the tooth surface for > 2 days mineralizes to form calculus that cannot be removed by brushing” (Merck Veterinary Manual, Periodontal Disease in Small Animals). Calculus is the hard yellow-brown tartar you can see.

The visible tartar isn’t the main problem. The damage happens under the gumline, where bacteria inflame the gum and, over time, destroy the bone and ligament holding the tooth.

2. Signs to look for

Merck lists the key signs as “bad breath (halitosis); plaque and calculus (tartar) accumulation; red, swollen, and bleeding gums (ie, gingivitis)”, among others.

Other signs an owner may notice include:

  • Chewing on one side, or dropping food.
  • Pawing at the mouth or rubbing the face.
  • A loose or missing tooth.
  • Swelling on the face, below the eye or along the jaw.

Many dogs with painful teeth keep eating. A dog who is still eating normally can still have dental pain.

Our note: We added chewing on one side, pawing at the mouth, loose teeth and facial swelling to Merck’s list from general knowledge.

3. Which dogs are most at risk

The UK study found that size mattered: “Increasing adult bodyweight was associated with progressively decreasing odds of periodontal disease.” Small dogs were more likely to be diagnosed.

The breeds with the highest odds in that study were the Toy Poodle, King Charles Spaniel, Greyhound and Cavalier King Charles Spaniel. Flat-faced (brachycephalic) dogs and spaniels as groups also had higher odds.

These are UK figures from dogs under first-opinion veterinary care. They show which dogs are more often diagnosed, not that any one dog will or won’t develop the disease.

4. What brushing can do

Brushing is the best thing an owner can do at home. Merck says that “Providing daily or at least every other day toothbrushing appears to be the most effective way to improve and maintain periodontal health.”

The timing matters because of the two-day window in §1. Brushing removes plaque before it hardens. Once it has hardened into calculus, Merck is clear that brushing can’t shift it: “While plaque can be removed by brushing, calculus can only be removed with professional scaling and polishing.”

What brushing can’t do is treat disease that is already under the gumline, or remove tartar. That is why a dog with established gum disease needs a professional cleaning first, and then brushing to keep the teeth clean afterwards.

Ask your vet or vet nurse to show you how to brush. Use a toothpaste made for dogs. Human toothpaste isn’t made to be swallowed.

Our note: Human toothpaste isn’t made to be swallowed. Use one made for dogs.

5. Chews, diets and hard objects

Owners are sold many products that claim to clean teeth. A few things are worth knowing.

Dry food on its own isn’t a toothbrush. Merck says that “The common perception that dry kibble (as opposed to canned food) decreases plaque and calculus through mechanical cleaning does not necessarily always hold true.”

Hard objects can break teeth. Merck warns that “Items that are hard (eg, bones, hooves) can crack teeth and should be avoided.”

Look for evidence behind a dental claim. The Veterinary Oral Health Council (VOHC), a council of veterinary dentists and dental scientists, awards a seal to products whose makers show they reduce plaque, tartar or both. It is open about how: “The VOHC does not test products itself.” Instead, “The Council reviews the submitted data to ensure it meets the clinical requirements to receive the Seal of Acceptance” (VOHC). A product without the seal may still work, but its claim hasn’t been through that review. We don’t name products.

VOHC also advises giving a chew of the right size for the dog’s weight, and only when someone can watch the dog chew it, because chews can cause blockages if swallowed.

Our note: The VOHC seal reviews data that come from the manufacturers. We haven’t read its protocols or how it is funded.

6. The cleaning under anaesthesia

Merck is plain about it: “Periodontal disease is diagnosed and treated under general anesthesia.” A full cleaning means scaling above and below the gumline, examining every tooth, and usually dental X-rays, which show the bone and roots that can’t be seen.

That can’t be done properly on a dog who is awake. → Anaesthesia-Free Dental Cleaning: What the Specialists Say

Many owners worry about anaesthesia, especially for an older dog. The risk is real, and your vet will assess it. A review of deaths around anaesthesia called them “an uncommon yet devastating outcome” and found that risk rises with poorer health, age and weight extremes, and urgent procedures (Rose, Wobeser & Pang, J Vet Diagn Invest 2026). Ask your vet what checks they do first, and how they monitor your dog.

Our note: We say a full cleaning “usually” includes X-rays. Many vets treat X-rays as standard.

7. Why it matters beyond the mouth

The new global dental guidelines from the World Small Animal Veterinary Association say that “un- and undertreated oral and dental diseases pose a significant animal welfare concern” (Niemiec et al., WSAVA Global Dental Guidelines, J Small Anim Pract 2026).

Gum disease has also been linked to disease elsewhere in the body. Merck notes that “periodontal disease has been associated with an increased risk of chronic azotemic kidney disease”. Associated means seen together, not proven to cause. The main reason to treat dental disease is simpler: it hurts.

8. What we could not verify

Commonly saidWhat we found
“80% of dogs have dental disease by age 2”Can’t verify. Merck gives “Up to 70% of cats and 80% of dogs”, citing a 1997 textbook we didn’t read. UK practice records give 12.52% diagnosed in a year. These measure different things.
“Dry food cleans teeth”Not reliably. Merck: “does not necessarily always hold true.”
“Bones keep teeth clean”Hard items can crack teeth. Merck says they “should be avoided.”
“Dental disease causes heart disease”Not shown. We found associations with kidney disease, not proof of cause.
“Tartar removal is the treatment”Not on its own. The disease is below the gumline.

Sources

Always confirm with your vet before acting on anything on this page.