Make sure your Pathfinding Cell border is High (maybe even equal to average Line of Sight?) This way Herbivores will stay readily away from Carnivores naturally as quickly as 1 second once they come into Line of Sight. Carnivores will not mark Herbivores or other Carnivores as Obstacles - therefore they can Path Find right to them.
Add Sprite Y as an Obstacle for Sprite X (Generally - Animals should always have other animals they wish to avoid as Obstacles in their Pathfinding)
Be sure to Regenerate the regions of the Pathfinding Grid as objects move (otherwise the Solid objects on the map won't update) - you'll probably want to do this in the most efficient way possible - try taking into account your Sprites Line of Sight and generating a Rectangle that size around your object. Use "Regenerate Region" and do..
Start X: SpriteX.X - (SpriteX.LineOfSight.Range / 2)
Start Y: SpriteX.Y - (SpriteX.LineOfSight.Range / 2)
End X: SpriteX.X - (SpriteX.LineOfSight.Range / 2)
End Y: SpriteX.Y - (SpriteX.LineOfSight.Range / 2)
Finally, Every 1 Second & Has Sight of THREAT > Find Path away from Threat
You may want to make the Pathfinding Cell Size/Border smaller for smoother movement on different animals.. but this will likely require more memory usage as a new Pathfinding grid would have to be generated for each unique size.