Why does my dog act ecstatic when she is around my baby lizard?

my 5 yr old female dog pants really heavily and scratches on my lizards tank. We cant introduce my lizard to my dog because he is still only a baby and she might hurt him. Because my lizard didnt get probed when he was born we dont know if it is a boy or girl. Please help cuz it happens all the time and we cant babysit my lizard 24/7. Also keeping my dog outside isnt an option cuz she is an inside dog. We r also getting a stand soon but dont know when.