Experts are warning dog owners to not use human toothpaste on their pets after research found that a whopping eight percent of canine owners have been doing this to fight their dogs’ bad breath.

The RSPCA explained that fluoride and the occasional use of the artificial sweetener xylitol in various toothpaste brands can be toxic to dogs if they swallow it. Dr Nicola Robinson, head of the Veterinary Poisons Information Service, said that fluoride can cause dogs to get diarrhea and vomit since it reduces calcium in the blood and increases levels of potassium.

Xylitol, which is also in certain types of toothpaste, could actually kill dogs.

“Not only will pets be less likely to tolerate the foaming and the minty flavour of human toothpaste but there is also a risk to their health from swallowing human toothpaste,” said Caroline Allen, London veterinary director at the RSPCA. “While there is a potential risk to pets from the ongoing swallowing of fluoride…the inclusion of the artificial sweetener xylitol in toothpastes is a more serious concern as this is much more toxic and products containing this ingredient should not be given to dogs.”

A spokeswoman for the charity Kennel Club said that pet owners whose dogs have bad breath should use special kinds of toothpaste on them instead of the products humans use.

“While we applaud owners who take responsibility for caring for their dogs teeth, we would also stress that only toothpaste formulated for dogs should ever be used,” said the Kennel Club spokeswoman. “Some specialist toothpastes for human-use contain ingredients which are unsafe for pets, for example xylitol, an artificial sweetener that is very poisonous to dogs.”

Dental hygiene for dogs is far more important than most pet owners even realize.

“A lot of dog owners aren’t aware of how important it is to look after their dog’s dental health,” said veterinary surgeon Rodney Zasman. “Poor care of dogs’ dental hygiene can result in (complications) such as dental plaque, gum disease, tooth abscesses and difficulty eating. Bacteria can spread from the teeth and gums causing damage to the kidneys, liver and the heart. Painful and extensive dental surgery and treatment may be needed to cure this.”