Is the use of Zinc Oxide sunscreen on dogs safe?
Question: Is the use of Zinc Oxide sunscreen on dogs safe?
Opinion is divided as to whether zinc oxide is safe to use as a sunscreen for dogs thanks to the fear that excess zinc may be toxic. But how much zinc is too much?
Studies of zinc toxicity in dogs are few and far between. Zinc is generally regarded as having low toxicity and the only reported cases of poisoning have been mainly related to puppies that have swallowed items made from zinc. The resultant problems included severe gastric upset and a condition called haemolytic anaemia, a situation where excess zinc causes the red blood cells to explode.
However, the dietary requirement for zinc in dogs is quite well known, and science has determined a healthy adult dog has an average body concentration of zinc of around 10mg per kilogram of body weight. In other words, the amount of zinc in a healthy adult dog of 20kgs is roughly 200mg of zinc, and the recommended daily intake of zinc to maintain this level is 1mg per kilogram bodyweight for adult dogs and 1.2mg per kilogram bodyweight for pregnant bitches and pups. This means the average manufactured food should include zinc at the level of 15mg per 1000kcal which equates to a dietary level of 52.5mg of zinc per kilogram of food for a standard adult diet.
On the other hand, zinc cream sunscreen contains 25% of zinc oxide, and zinc oxide comprises 78% elemental zinc. This means one gram of sunscreen contains 195 milligrams of zinc. In-depth human studies have shown the average application rate of zinc cream is 4.3 milligrams of cream per square centimetre of skin, containing just over 0.8mg of zinc. So, a small dog with a skin area of two square centimetres will have 1.7mg of zinc on its nose, whereas a large breed dog may have as much as 6.7mg of zinc on its nose following a standard or average application.
This equates to 0.17mg of zinc per kilogram bodyweight for both the small dog weighing 10kg bodyweight, and the large dog with a bodyweight of 40kg. Put another way, were the dog to lick the entire coating of sunscreen from its nose, it would increase its daily intake of zinc by 17% of the recommended minimum daily allowance, a quantity which simply can’t be classified as an unhealthy or hazardous amount.
At these levels it appears unlikely the intermittent use of zinc cream on a dog’s nose is going to offer any danger to the health of the animal. However, there are reports that dog skin is different to human skin and that long term exposure to zinc creams will cause irritation to the canine’s nose. In situations where continued exposure warrants the daily application of sunscreen, it may well be more appropriate to consider the use of a sunscreen that does not contain zinc. If you do choose this option, please ensure you are not jumping out of the frying pan and into the fire by selecting a sunscreen containing other components such as PABA or salicylates which are both listed as toxic to dogs. There are a number of preparations available on the market that specifically satisfy a dog’s need for sunscreen.
In summary, and although it may be uncommon or even rare, a decent dose of common sense will ultimately be the best guide!
About the author… Bill Wiadrowski is a consulting nutritionist who has worked in the field of performance animal nutrition for over 50 years. His latest development is the LifeWise range of next generation foods that are rapidly gaining acclaim for their ability to repair common gut and skin sensitivities issues in domestic canines.