Electric heated waterers are notorious for stray voltage. If you see cows lapping at the water, that's a sure sign they are getting shocked. Give the cows straw or hay to lie on, not mud. Teats and udders. Dry teats and udders before cows go outside.
Chapped teats can lead to mastitis.
Do what you can so cows don't have to walk through frozen mud. The sharp edges and holes can bruise or cut cows' feet.