Yes. This is for the safety of your pet. Under normal conditions and in familiar environments, your dog may listen to you and follow your lead very well. However, vet clinics can be stressful environments for some animals. A loud noise on the street or something in the clinic that startles your dog may cause your dog to react in ways that you do not normally see, like trying to bolt out the door. And while you may trust YOUR pet, we do see animals that do not like other animals and can become aggressive in the presence of other animals. If your dog walks up to another dog that has a tendency to be aggressive, a serious fight could occur. Also, there are times when animals who come for appointments are seriously ill. If your pet interacts with a sick pet, there is always the chance that your pet may also contract that illness. Therefore we ask all clients to leash their dogs when coming in for appointments and keep your dog close to you. This is for the health and safety of your dog and the other dogs in the clinic.