Many Bull Terriers have a tendency to develop skin allergies.[9] Insect bites, such as those from fleas, and sometimes mosquitoes and mites, can produce a generalised allergic response of hives, rash, and itching. A UK breed survey puts their median lifespan at 10 years and their mean at 9 years (1 s.f., RSE = 13.87% 2 d. p.), with a good number of dogs living to 10–15 years.[10]