I have seen 4:1 in prop trading (I think that Questtrade have already offer it for prop trading), but few brokers will offer it. Each time this will base on select case and negociation are required, also you will have to exhibit your trading c.v. and some solid financial proof, not very standard in Canada. 3:1 is more frequent but not standard usually (Tradefreedom, Jitneyonline group and Disnat Direct).
As you seen, even if the country is near the USA, we are far from the US brokers for many things!