In my opinion, Manitoba is open to immigrants with any kind of job. But they will base their approval on how the immigrants prepare their documents, answer the SP1 and how strong their ties are in Manitoba.
MPNP has been accepting immigrants with regulated jobs, that means they cannot immediately work in their field of job experience, but they are willing to do any kind of jobs to contribute to the economy. They also contribute by paying tuition fees as they have to study in order to have the licence.
As long as you can support yourself while preparing for being a licensed vet in Manitoba, I don't see any reason why you shouldn't try. End of the day, you will never know if you are eligible until you apply.