RPGMemes

I feel like, related to this meme, cats in particular would be a lot more common, and trained to hunt pests. Sure, most people can't identify one rat from another, but they can identify cats. The cars kill infiltrators (druid or just pests), and they cut their numbers down so new ones are more obvious. They themselves are known to the guards so they know if some new cat appears.

The same is true for dogs, and they could sniff out intruders. They could also be trained to hunt, which could be useful for a different set of pests. I'd imagine, in this world, probably hawks or something would be really common for guard stations too, and people would be used to identifying them. They would have developed tactics to deal with this that aren't necessarily common or available in our world.