The cats were mainly indoor cats owned by one person – a pretty classical case of cat hoarding. All were in very poor condition. There were vaccination records for 15 of them, but there was no way to figure out which record corresponded to which cat (e.g. "black cat" doesn’t help much when you have 30 black cats in the group).
Since all of the cats had to be considered unvaccinated and they were exposed to a rabid animal, that left two options: euthanasia or 6 month quarantine. The logistics and cost of a 6 month quarantine, along with the poor condition of the cats themselves (and probably concerns about finding adequate homes after quarantine) led to the decision to euthanize the group.
Sometimes, these decisions have to be made despite knowing that the true risk of rabies exposure was very low. However, that’s not the case here. There was one confirmed rabid kitten, but other kittens in the litter had already died by the time that one was tested. The others may have also had rabies. The kittens had to get rabies from something, and if they were indoor (which is probably the case here given the primarily indoor nature of this group and their age), that means the virus probably came from one of the indoor-outdoor cats or from the mother (no word on her health status), which means there were multiple potential sources of exposure for the larger group than the one kitten that tested positive.
In some ways, they got lucky here. The kitten was taken to a veterinary clinic, where it bit a technician. The clinic fortunately did things right and reported the bite, and the kitten was tested. Otherwise, this would not have been picked up and there’s a much greater chance that the owner or someone else would have been exposed, and possibly died.
Inadequate rabies vaccination of this group led to the deaths of 50 cats, expensive post-exposure treatment of a few people (the veterinary technician, an animal control officer who was also bitten, and likely the owner), and presumably a lot of time and effort investigating this.
This case, and other recent rabies diagnoses, is plotted on wormsandgermsmap.com
More information about rabies is also available on the Worms & Germs Resources – Pets page.