I have arthritis and used to suffer doing almost anything until a friend told me that drinking water into which a small amount of magnesium chloride has been dissolved would help. I didn't believe it but thought I'd try it anyway. Believe me, it WORKS! Dissolve about a teaspoon of it into 2 quarts of water. Drink about half a cup first thing every morning and then another half cup before dinner every evening. Almost all of your pain will go away! And then you can continue milking with your own hands, which I'm sure your animals would far prefer to some contraption hooked up to them. Good Luck!
