This is literally why we have apex predators such as wolves. They help clamp down on the old and the sick so that prions (mad cow disease) does not spread to other species or humans. It cannot infect wolves.
When you kill off all the apex predators, like when Montana governor Greg Gianforte authorized the massacre of 100 wolves, you see explosions of extremely dangerous diseases and land degradation as deer damage tree roots, gardens, meadows, streams, and farms.
Not only that, but killing members of wolf packs causes their families to fall apart and everyone to scatter. That means wolves alone. Which cannot hunt pack animals which require coordination. So then they go after the easiest meal: dumbass farm animals who have zero survival instincts and whose ranchers no longer employ people to look after the herds in great enough numbers like the olden days. The cycle then perpetuates, as mad-cow contaminated soils spread and spread…