Hope this might help you,i have also a shih tzu dog and she is 2 years old now..Sine she was a pup,she has being sleeping in my room on the bed with me with aircorn on also..So far till now after 2 years of sleeping with me,she did not catch cold..So,it should be fine...Shih tzu coating also is quite long so should be able to stand the coldness =p..