I have no doubt that animals can sense fear, but if it’s really based on smell, wouldn’t you have to do more than just act like you’re not afraid? You would need to find a way to control either your scent or your actual fear.
I wouldn’t be surprised. Some reports state that certain breeds of dogs have olfactory glands a million times more sensitive than humans.
Heck they have trained dogs to sniff for cancer!
ETA: So why not adrenalin?