Clean it gently with soap and water. Trim away dead skin. If it's less than the size of a quarter (2cm or 2/3in), you can rinse it with hydrogen peroxide or betadine, bandage, and do a wound check...
clean area carefully try not to open blister bandage and keep dry
Take it to the vet
Advanced Foot Care Limited is the human health business based in Liverpool
Pawpaw cream and a bandaid