It's unclear what chemical in particular caused the kitten's reaction, but propoxur, a chemical used in brands like Sergeant's, has been known to cause such symptoms. Sergeant's didn't immediately reply to The Dodo's request for comment.
But, as it turns out, propoxur - whether or not it was the offending chemical - may be be on its way out. The company has reportedly agreed to discontinue products that contain the pesticide. But that phaseout wasn't complete until April 1, meaning the products may still be hanging around people's homes and even on some store shelves.
Even so, Harrelle says, any flea collar that uses a toxin to kill fleas does so by entering the bloodstream. And the results can be unpredictable.
"It's the equivalent of putting a toxin on the back of them and it's absorbed in the skin and gets into the bloodstream," she says. "The toxin can affect any animal at any age. We just see it more frequently in the really young ones because they're more susceptible because of their weight and age."
The kitten in this case survived - and grew up to be the fine cat she was supposed to be.
But we've also seen the tragic side of similar products before.
A woman in Georgia told The Dodo earlier this year that her cat didn't survive his experience with a Sergeant's Dual Action Collar - although, again, it's unclear if it was the type of collar that contained propoxur. Shortly after Teresa Crandall strapped the collar around the neck of her cat Onyx, he underwent a terrifying transformation: blindness, seizures, paralysis and finally death.