Aside from your pet’s leash, harness, toys and blanket, there are a number of items that can make for a more pleasant camping experience for him.
You can get a tag for your cat or dog from your local pet store, and can even have it inscribed with your telephone number.
If your pet gets lost, any good Samaritan who finds him can call you.
Your veterinarian can advise you on appropriate items for your dog or cat. These may include eye drops, anti-nausea drugs, disinfectant, etc.
You should also bring a bottle of special shampoo, in case your pet has an encounter with a skunk.
With a special backpack your dog can comfortably carry his own food and water on the trail. Check at your local pet store.
If you have to leave your pet alone in the car, make sure he gets some fresh air. You can install a window ventilation grill, and leave the window open with no danger of anyone breaking in. Adjustable grills to fit most cars can be found at most pet stores.