All cats get hurt. Here's what the injuries are:

Hurt against fighting another animal

Falling out of a tree

Whitecough/greencough

Stomach problems

Dislocated shoulder

Ripped claw

Thunderpath injuries

Twoleg traps injuries

Border skirmish

Natural disaster debris

The medicine cats can cure all of those, but they take different amounts of herbs for each one. Medicine cats, remember to restock the herb store regularly!