eleannaDDS is correct. Most students have completed 4 years and have degrees. However, there are always exceptions where students get in after 3 years.
I know that U of T is starting an interview process this year, so this component will replace the essay worth 20%. The DAT will be worth 10% (5% for academic and 5% for PAT). Thus leaving 70% for GPA.
If you apply during your 3rd year....then U of T will count your first 2 years and not your current last 3rd year. If you apply during your 4th year then U of T will count your 3rd year and either your first or second, whichever one is higher.
Western, counts only your best 2 years I believe. But you have to take there requirements, one being human physiology.
For the US, every year is taken into account.
Hope this helps....