My dog has been limping on and off on her back leg and I saw a tinny black bug crawling on her

最佳回答：

She may have fleas if you saw something crawling on her. Get a flea comb and check if she has fleas. If she does, use a flea treatment like Frontline, Advantage, or NexGard. The limp is probably unrelated and if it continues have her examined by a vet for X-rays and treatment.