I went to school for vet tech
The main courses I needed were english, chemistry, biology, and math. The best thing to do is to look online for the schools that offer the veterinarian technician program, and see what the requirements are.
This is what Seneca says, but it may vary depending on the school.
* Ontario Secondary School Diploma with a majority of senior credits at the College Preparation (C), University Preparation (U) or University/College Preparation (M) level or Mature Student Status (age 19 or older).
* Grade 12 English: ENG4(C) or ENG4(U).
* Grade 11 Biology (C) or (U).
* Grade 12 Chemistry (C) or (U).
* Grade 12 Mathematics: (C) or (U) or Grade 11 Mathematics (U) or (M).