Besides the typical runny eyes and nose, cats can have flea bite allergies that cause them to lick or chew the base of their tails as well as chew on their paws. (fourleggedguru.com)
Check them over regularly from the tip of their head to the tip of their tail for any lumps or bumps. (timberlineanimalhospital.net)
In affected dogs, you will typically notice a bald spot at the end of the tail where the skin wasn't trimmed correctly. (pethelpful.com)