LABORATORY tests have pinpointed what has been plaguing the stray cats at Bayshore Park condominium - a chemical used to immobilise mice and bird pests.

However, the mystery remains as to who is behind the deliberate poisoning.

Traces of alpha-chloralose, a coma-inducing drug, were detected in samples of food planted all over the estate. The chemical was also found in the liver and kidney of one of the cats, during an autopsy by the Health Sciences Authority's Toxicology Department.

On June 11, the nine cats- all mysteriously disoriented or unconscious - were discovered around the East Coast estate. Over the next few days, more cats, and even some birds, fell sick.

In all, the Society for the Prevention of Cruelty to Animals (SPCA) took in 21 stray cats from the estate, which accounted for more than half of the total number of strays at the condominium.

Five of them died or had to be put down as they were not responding to treatment by staff at the SPCA.

Fifteen other cats have since been sterilised and released back into the estate, while a kitten remains in the society's care, awaiting adoption.

Alpha-chloralose is a potentially lethal drug that acts as a soporific, and causes seizures and muscle tremors among other symptoms.

In Singapore, alpha-chloralose is classified as a poison and can be sold only with a licence under the Poisons Act. However, the HSA said that the Act applies only to medication consumed by humans. One vet The Straits Times spoke to said that the drug is not commonly used by vets in Singapore, even as a sedative, as there are other options which are 'safer and better'.

The revelation is cold comfort to Bayshore residents, who are saddened by the proof that someone is indeed out to poison the animals. 'We were very alarmed but we are still maintaining vigilance, especially now that the cats are back. If it happened once, it can happen again,' said one long-time resident.

Please read the full story in Tuesday's edition of The Straits Times.

kimspyke@sph.com.sg