Kind of curious do they grow back

I was outside checking my vegetable garden. Josh mom came outside and came over to talk to me. They got a older dog he is like 17 up to 19 year's old. Last night she was getting ready for bed and she notice blood on the bed and next to it was a nail. She really thought it was a tooth. She look at her dog and he had his teeth and notice blood on his foot and one of his nails had completely came off. So I am kind of curious will the nail regrow ?