Serrata is a toxin artificially created by the Nayabaru that works primarily on Tetanurae and has no effect on mammals. The Nayabaru 'infect' wild rodents with Serrata so that they'll be eaten by kavkema, which are the primary intended recipient of the toxin.
Serrata causes an increasingly spotty vision. An hour after ingestion, blindness sets in, lasting up to five hours. Associated with the swimming blotches of missing visual input are visual hallucinations, for kavkema often taking the form of kiikama. While not inherent to the toxin itself, tactile and audio hallucinations can occur simply from the brain desperately trying to fill in the blanks.
A secondary effect of Serrata is a burning sensation within the ribcage, making a lot of affected kavkem struggle to stay quiet. Naturally, this is a desired side-effect, as it makes them easier to discover - and quite easy to handle in their agonised state.