Animals captured by the Cynid Conclave are implanted with a kind of biomechanical worm called a "Brain Leech", it essentially keeps captives under control by punishing them with a stunning electric shock if they do anything they aren't allowed to, and allows the animal to be tracked by satellite. The parasite itself feeds off the brain's synapses, so the host commonly experiences a mild headache. Soot the rabbit has discovered a way of removing the parasite, and is giving Tek the treatment.

Drawn up by the wonderful  picormdwe , but you can see her stuff at picormdwe.deviantart.com since that account's pretty inactive