add check for 'injured' animation

api.lua

@@ -3036,8 +3036,8 @@ function mob_class:on_punch(hitter, tflp, tool_capabilities, dir, damage)
 		-- turn mob on knockback and play run/walk animation
 		self:set_yaw((random(0, 360) - 180) / 180 * pi, 12)
 
-		if self.animation and self.animation.run_end then
-			self:set_animation("run")
+		if self.animation and self.animation.injured_end and damage >= 1 then
+			self:set_animation("injured")
 		else
 			self:set_animation("walk")
 		end

api.txt

@@ -249,6 +249,9 @@ functions needed for the mob to work properly which contains the following:
       'shoot_start'  shooting animation.
       'shoot_end'
       'shoot_speed'
+      'injured_start' when hit or damaged > 1 hp (if not set then 'walk' is used)
+      'injured_end'
+      'injured_speed'
       'die_start'    death animation
       'die_end'
       'die_speed'