There has been a big push in the veterinary world in recent years to try and increase dental hygiene in pets. Vets are encouraging owners more and more to make brushing their dog or cat’s teeth, to remove plaque build-up, part of the daily routine, like you would walking or feeding them. Companies have, of course, jumped on this trend, and developed products designed to improve dental hygiene, including pet toothbrushes, toothpaste, and now ‘doggy mouthwash’.
Doggy mouthwash is added to dog and cat water bowls to ‘help fight your pet’s bad breath’. The main ingredients, chlorhexidine and xylitol, are supposed to kill bacteria and reduce plaque, with the advantage being that the liquid can reach where traditional brushing might not. Anecdotal evidence and product reviews indicate these products do help reduce bad breath and keep teeth looking cleaner. However, there’s been a recent hubbub around the inclusion of xylitol in the ingredients.
Xylitol is a sugar-alcohol, commonly used as an artificial sweetener in products such as sugar-free chewing gum, certain toothpastes, and some drugs. Xylitol is, of course, toxic to dogs (there has been no reported evidence of toxicosis in cats), with low doses (75-100mg/kg) causing rapid release of insulin, leading to acute low blood sugar and associated depression, weakness, wobbliness, seizures and coma. Higher doses (>500mg/kg) have led to liver failure, presenting as vomiting, depression, jaundice and death.
It is not uncommon for dogs that have eaten owners’ sugar-free gum, or other food with the sweetener added, to be brought into practices with xylitol poisoning. The best treatment is rapid vomiting before the xylitol is absorbed, though hypoglycaemia (low blood sugar) often does not present for many hours after ingestion, and liver injury can take over a day to present, so by then it can be too late. Further treatment involves stabilisation on fluids to counter the hypoglycaemia, and the prognosis is usually good. Later stage toxicity is unfortunately less well managed, and high levels of liver enzymes usually indicate irreversible liver damage – many of these advanced cases die or are euthanised.
Is Doggy Mouthwash Dangerous?
The very real danger of xylitol has meant that some dog owners have taken issue with the fact that this potentially harmful substance is in a product designed to be swallowed! At face value, this might make sense, but further investigation proves that there is actually little danger when using doggy mouthwash properly (warning: maths incoming!).
The product’s ingredient list states that there is 5mg/ml (0.5%) of xylitol in it. Using the lowest value that can cause hypoglycaemia (75mg/kg), an average 7kg pug would have to ingest over 100ml of doggy mouthwash to induce hypoglycaemia. A somewhat chunky Labrador of 30kg would have to drink around 450ml. Bottles are available in 250ml and 500ml sizes, meaning this Lab would have to ingest at least two smaller bottles, or one larger, to cause hypoglycaemia.
If we are considering the more serious liver failure, which can be caused by xylitol ingestion of over 500mg/kg, our pug would have to drink at least 700ml, and the Lab over 3 litres! Considering this is a huge volume of water to drink for the average pet, the risk of a dog managing this is slim.
Furthermore, this assumes that the dog has gotten hold of the sealed bottle and drunk it all neat! When used correctly, according to product information, 1ml of doggy mouthwash is added to every 100ml of drinking water. Since this increases the volume of water needed to cause poisoning by a factor of 100, the risk of xylitol toxicity from correctly used product is zero – water toxicity would occur long before xylitol toxicity!
So when we look at the figures involved, there is indeed a very small risk of xylitol toxicity if a dog manages to open a bottle of doggy mouthwash and drink a considerable amount, especially if they are a small dog. This risk is very low compared to the risk of chocolate toxicosis, for example, which is much easier to open and consume, than bottles of xylitol-based doggy mouthwash. When the doggy mouthwash is used correctly, there is no danger at all from xylitol toxicity.
The purported benefits of using doggy mouthwash far outweigh the negligible risk of xylitol toxicity, and if the use of such a product increases owner awareness of dental hygiene in pets, then at the very least it should be mentioned in practice when discussing the issue.