Just wanted to add that you mentioned iodine as leaving a metallic odor. I had been dabbing a sore at the back of the neck with a little iodine. It was in an area where it wouldn't be licked off but I think he scratched it, got it on his paws and licked if off. Once I stopped the iodine, the smell disappeared from the urine. So, thank you, for your help im narrowing down what was causing the metallic smell.