Don't bring your pets - or livestock - to Glastonbury !
No animals are allowed onto the Festival site; it wouldn't be much fun for them anyway. People and vehicles entering the site are normally searched, and any animals found are impounded and housed off-site at the owners' expense.
The ban on animals is a condition of the Festival Licence; it arose due to the health risks observed in early festivals, when large packs of dogs gathered. Animal shit, animal bites, loose animals frightening or attacking children, animals frightened of the crowds, noise and fireworks - Glastonbury is a better event with no animals. Don't bring them.