I have a little graveyard for pets, including 2 dogs that were euthanized by veterinarians. I buried the dogs about 3 feet deep and piled big rocks over them so nothing can get to them. I recently buried a rabbit that died of natural causes near a dog that was euthanized about 14 months ago, and I planted a little comfrey start on top of the bunny. But then I got to thinking that comfrey puts down deep roots – is there a chance it will pull up the drugs and be harmful to anything that eats it? I’m just not sure how long the drugs remain toxic, or if they would still be harmful if taken up by the plant.