Most countries including Canada have regulations in this regard. The Canadian Regulations are found at:
http://www.cta-otc.gc.ca/access/regs/air_e.html
Service animals
Properly trained guide dogs and other service animals are allowed on board the aircraft at no extra charge. Service animals are permitted to remain on the floor at the passenger's feet as long as they are properly harnessed. Passengers should note that they may be required to produce written proof that their service animal has been trained by a professional service animal institution.
The original ban on Service animals in the Passenger Cabin for flights to the UK had nothing to do with any problems with the service animals but everything to do with UK quarantine laws for Dogs.....