I am looking to buy Louis a puppia harness. I am not sure what size to get. He normally weighs 6lbs 8ozs (just recently he weighed 5lbs 8ozs because he was treated for pancreatitis
) I am sure he will be back to his normal weight soon. His chest is 13." The size chart for puppia says xs for his chest, but size s for his normal weight. Should I go by his chest or his weight? Does anyone else have one and what is your dogs size/measurements? Thanks!