I have heard good and bad things about MSM. I would be inclined to try some of the other natural supplements known to help first.

 

I know kitties do not handle aspirin of any type at all. They do not detox very well. I don't know about dogs. I do know dogs have better detoxing abilities.

 

I don't think lavender is toxic, but then again, the kitties never try to eat any. I sprinkle a small amount of dried lavender blossoms (I grow it in the garden) between the sheets of newspaper at the bottom of the cat carriers when transporting kitties to calm them during the trip and I do believe it is helping. That aromotherapy stuff you know. I use a very small amount as I know essential oils can be toxic to cats and my blossoms are pretty potent.

 

As for your dogs, gee, they may be going for their own "aromotherapy sessions".  Tee hee!

Dee