I have flown numerous times with my smaller dog in the cabin with me (I would never ship an animal). I recently travelled with WestJet in April . I bought a soft-sided carrying case for under $20 from Walmart. (As a side note, Air Canada discontinued allowing dogs in the cabin due to passengers' allergies.)
The requirement of most airlines, including West Jet, is that the dog be under 20 lbs and be able to fit under a seat. My dog is only 10 lbs but he has extremely long legs, so it would be impossible for him to fit under a seat if he were standing. So I sedate him, he sleeps quietly, and we're happy.
The check-in personnel never examine the case or even look over the counter. I could have an gorilla in the case for all they would care. The only strict rule that the airlines all seem to have is that the pet MUST stay in the case while on board, and you must keep the zippers closed.
My friend recently flew with her small dog in the cabin. She unzipped the dog's case so she could pat her dog, and it got out and ran through the cabin. I told her she will ruin it for the rest of us.
