Some residents of the Narbonne region of southern France have noticed that some streets cats vomited a blue substance. They meow weakly and die. It sounds awful. And in such large numbers.

Local animal welfare organisations blamed poisoning; rat poison, cannabis or motor oil in cat food.

But autopsies were carried out on two cats and they said the cause of death was feline calicivirus (one of two viruses causing the ‘cat cold’). To me, this seems unlikely to be the cause because this infection does not cause a blue substance to be vomited. Bile can be vomited due to an inflammation of the intestine for instance but bile is yellowish.

The speed of death and the vomiting definitely points to poisoning. I wondered if antifreeze is produced in a blue color. The answer is Yes. There are various colors of antifreeze one of which is blue.

My guess is that this is a case of a mass poisoning and someone is using blue colored antifreeze. The cat vomits it and then suffers terminal kidney failure and dies.

We have not been told what happened but if the authorities have decided it is a cat cold they’ll do nothing. Something should be done: an investigation as to whether hundreds of cats are being deliberately poisoned. There may be a unwritten policy on the southern French coast to get rid of the street cats after the tourist season as they do in Greece. My bet is on that and the police are probably turning a blind eye.