After Tony Jones had fed his guinea pigs fresh greens at his home in Sandiacre he was surprised that days later they had not eaten them. After a closer inspection he found they were laced with blue slug pellets. He bought the greens from Tesco in Long Eaton on February 4th while doing the weekly shop. After returning the greens to the store and complaining he was given a £10 gift voucher. A Tesco spokesman said: "We are investigating what may have happened and will keep Mr Jones updated."