The owner did not want the cat to get poisoned in the event the rat had ingested poison. Rat poison works its way up the food chain, as the Griffith Park Mountain Lion, P-22's bout with mange highlighted the way rat poison weakens the immune systems of the animals further up the food chain. P-22 recovered with veterinary assistance, but he was a much larger animal than a killer house cat. House cats are extremely sensitive to poisons. Bobcat deaths from the effects of secondary poisoning are epidemic in the Los Angeles Area.
Another neighbor contacted me last week after finding a dead rat on the sidewalk. The rat showed no sign of trauma or puncture woulds. The neighbor suspects rat poison and is concerned that people dispose of dead rats appropriately - bag up the dead rat and throw it in the trash. DO NOT throw rats retrieved by your cat or killed in a trap, into a vacant lot, your neighbor's yard or in the street. A cat, some dogs and scavengers may ingest poison causing serious illness or potentially death.
Read more abut the dangers of rat poison in the food chain: Urban Carnivores.
