The American Veterinary Medical Association said symptoms to watch for include a staggering gait, the inability to retract claws, extreme sensitivity to touch, tremors, and seizures. The illness usually lasts for a few days to a few weeks, but can also linger for more than a year.
Then support your local trap/spay/neuter charities. This is a miserable and painful way for them to die and likely wouldn’t kill enough of them to get the effect you’re hoping for. All you’re wishing for here is needless suffering.