Copaiba
Copaiba is an essential oil from a South American tree that has amazing anti-inflammatory properties. It can safely be applied directly on the skin for arthritis and skin problems either undiluted (neat) in very small amounts, or the preferred way, diluted in a carrier oil such as coconut oil. I use it as an ingredient in my Pet Dental Spray to help with inflamed gums.
Please see my article, How to Safely Use Essential Oils in Pets for correct and safe ways to use essential oils in pets.