The legislation is currently being tabled in Parliament, Beeld reported on Wednesday.
A year of community service for doctors and dentists is already compulsory, and the government wants vets to perform the same duty.
Dr Rebone Moerane, chairperson of the SA Veterinary Council, told the parliamentary portfolio committee on agriculture on Tuesday that if new graduates decided to go and work overseas two months into their community service year, the council would act against them.
"The moment that country requests a reference letter from the council, we will refuse to issue it. If that vet tries to practise here, the council will not renew his or her annual registration."
Dr Pieter Mulder, deputy minister of agriculture, led a delegation from his department on Tuesday to make a submission about the draft legislation to Parliament.
Mulder said around 45% of new vets left the country just after graduating.
South Africa currently has 2 900 vets, of whom 250 work for the government, and 200 work in private practice in rural areas.