The safety of the herd is paramount - for the shepherd. Not because he loves his sheep, but because he loves a lazy meal and an easy shearing.
Fear not the good shepherd, nor the bad shepherd, but the craven shepherd.
Bighorn sheep defend themselves from wolves, bears, cougars... and hungry shepherds. Therefore the craven shepherd hates Bighorn sheep above all. He fears they will crossbreed with his domesticated flock, or lead the flock away to free pastures. His flock's weak rams quail before Bighorn titans.
That's why the craven shepherd butchers his more troublesome rams in the lean winter months and feeds their guts to the wolves, keeping the super-pack strong to hunt the Bighorn to extinction year-round.
The craven shepherd's dogs keep his flock safe from wolves and thieves, and savage any ram who dreams of going off-reservation.
The domestication of the herd is the security of the shepherd. Vaccination of the young, healthy and not-at-risk is partly to protect elderly oligarchs, but moreso a genuflection before the craven altar of the Nanny State, whose material bounty is as great as her spiritual emptiness.