Dog days - Geraldine McCaughrean

'The ice was slippery. Her paws kept splaying outwards until the cold of the ice on her belly made her tiptoe back up to her full height . . . Someone on the bridge threw a lump of coal at her. It skidded across the whiteness, leaving a black trail, then plopped into a fissure: the ice was breaking up.'

Clay and his brother, Hal, rescue a struggling dog from the icy River Thames. But back on dry land their father refuses to take her in - the new Dog Tax means she's too expensive to keep. As skinners sharpen their knives, ready to make money from pelts just like hers, the boys determine to save her - at whatever cost . . .