"Mandy is keen to see Tilly the Dexter calf win a prize at the Welford County Show. But strange things keep happening to Tilly and her mum, Jenny. It looks like someone doesn't want them to take part in the show at all. Mandy and James are determined to find out what's going on!"
I'm not sure if this book from Animal Ark is still available because when I clicked the Buy the Book link it was now Bunnies in the Bathroom by the same author.