There has been a lot of research into artemisin, but not in American literature. I supervised a farm growing 120 acres of the plant to be broken down by super critical carbon dioxide solvents to treat malaria. Use o the herb goes back at least 2,000 years. Indeed the problem with all herbal meds is the inability to determine an exact dosage. The reason for the extraction process is to produce a measureable consistant dose to provide clinical trails. We used selective breeding of the plants, and the variation was up to 10 times in medicine in a given plant. Over ten years we optimized the amount of medicine from each plant, however purchasing the plant is russian roulette, unfortunately. We recently shut down the farm so I can no longer supply anyone with high-quality artemisia.
Congratulation's on your dog's longevity. I hope he continues to do well.
Just a quick note. Prednisone should work as well as prednisolone in your boxer. Prednisolone is more important in cats.
The dose of Artemisinin is 200mg daily for a boxer sized dog. We use Allergy research or NutriCology brands at my practice. If your dog is currently taking more than 200mg and there are no side effects than continue with the higher dose. If he is taking less than gradually increase to the 200mg dose.
There are many other additional holistic options to consider. Please post again if your would like additional information.
Thank you, Dr. Aleda Cheng