No cattle or other animals apart from pigs, I think he is meant to have a visit a year same as for cattle/sheep, all drugs are obtained properly from the vet, nothing underhandQuarterly visits are a requirement for all RT assured pigs, as far as I know. Your mate may not be RT assured.
As far as the 'under care of' thing goes, your mate may not need to treat any of his pigs, and if he does he can call the vet out. Ergo, they would be under the vet's care.
Or maybe he just uses the Betamox he has been prescribed to care for his cattle, and doesn't tell anyone (possibly because he doesn't know any better).
Not that he needs many
Quarterly must be an rt thing