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The Trust Me Big Experiment – What’s the best way to keep your pet’s teeth clean?

What is periodontal disease?

One of the biggest problems in pet health across this country is dental disease. I’ve lost count of the number of times I’ve diagnosed serious illnesses in animals that could be traced back to poor oral hygiene. So we at Trust Me I’m a Vet decided to do a big experiment to tackle it.

Periodontal disease is caused by an inflammation of an animal’s teeth and gums. It’s a surprisingly common condition, affecting over 87% of dogs and 70% of cats. Preventing it is essential to the health of your pet.

How it develops

Food particles and bacteria combine in the mouth to create plaque which, over time, transforms into calculus. Calculus allows more plaque to rapidly colonise the tooth surface. This causes gum irritation and leads to an inflammatory condition called gingivitis. Persistent bad breath, known as halitosis, is a sign that your dog is likely to have gum disease, but you should also look out for a reddening of the gums directly bordering the teeth.

Why it matters for your pet’s health

Over time, the calculus and plaque migrate below the gum line, forcing it away from the tooth and allowing more bacteria to grow in the space. In turn, the bone below the tooth retreats and further tissue destruction follows.

At this stage bacteria from the mouth can move from the damaged gum into the blood stream, causing damage to the kidneys, liver and heart and shortening the life of your pet.

How to prevent periodontal disease

Cleaning your dog or cat’s teeth regularly is essential to prevent the build-up of plaque and prevent gum disease. There are plenty of products available on the market to help you achieve this:

  • Dental chews
  • Dental kibble (dry food)
  • Breath tablets
  • Mouth sprays
  • Brushing teeth, using pet toothpaste & toothbrushes. Never use human toothpaste as fluoride can be toxic to cats and dogs

All of these products have been tested in laboratories by manufacturers before they are made available to buy in shops. However, only some have been tested in clinical trials for effectiveness in reducing plaque build-up. Most of them have never been trialled in a home setting, nor have they been tested against each other to find out which is the most effective at keeping plaque at bay.

Our Study

We joined forces with leading veterinary dental specialist Norman Johnston and veterinary surgeon Ross Allan to test which of the following methods was most effective:

  • Tooth brushing
  • Dental Chews
  • Dental Kibble


Three different groups of dog owners each used one of the three teeth-cleaning methods with their dogs, for 6 weeks. Our dogs were:

  • Between 1 and 5 years old
  • Between 10 and 20kg
  • Had a similar skull shape and size
  • Free of broken or missing teeth
  • Had no dietary restrictions
  • Would allow their owners to brush their teeth without resisting

All dogs were recruited through owners volunteering to take part and were already registered with veterinary practice “Pets ‘n’ Vets”.

All our dogs were seen by a pet dentist to have their teeth cleaned and polished before the study started, to allow valid comparisons of their dental health at the end.

27 dogs were enrolled on the study and were assigned at random to one of the three groups.


Of the 27 enrolled, 22 dogs completed the trial.

At the end of six weeks the 22 dogs returned to “Pets ‘n’ Vets” to have their teeth examined using plaque-disclosing fluid, which colours plaque on the teeth and gums. Their teeth were given a final score based on how much plaque had built up during the trial.

A dog with no plaque or calculus would have a mouth score of zero, so the lower the score, the better the result.

Our study showed:

  • Dogs fed on dental kibble had a median mouth score of 4.65
  • Dogs given dental chews daily had a median mouth score of 4.10
  • Dogs who had their teeth brushed daily had a median mouth score of 1.25

Tooth brushing resulted in a significantly lower average mouth score compared to dental kibble or dental chews, which both had similar results.

Our study has shown that tooth brushing is the best way to keep your dog’s teeth free from plaque. Based on this study and previous research, expert Norman Johnston declares tooth brushing the ‘gold standard’ for oral hygiene in both cats and dogs.

How to brush your dog's teeth

The group of dog owners find out about canine teeth brushing

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