How your pet adjusts to boarding will depend on several factors. Many dogs are very content at a boarding facility, while others lose their appetites and long for home. Cats are both better and worse clients. They generally hate change and travel, so they may be unhappy at a boarding facility. But they rarely get so upset that they refuse to eat or drink.
You may like to assume that your pet's discomfort at a boarding facility is due to its unbearable longing for you. But there are plenty of other reasons a pet doesn't enjoy the kennel. A dog that's used to plenty of outdoor exercise may be fine for a day or two at a kennel, but any longer and it will want more exercise than it can get in a small run. A dog that's used to enjoying table scraps with dinner every night may refuse to eat, not because it's stressed, but because it's protesting the bland diet.
So how can you ensure your pet has the best time possible during its boarding facility stay? In the time leading up to your departure, note the amount of exercise your pet gets on an average day. Compare that to the amount of time the boarding facility will exercise it. If it appears that your pet will be more sedentary at the boarding facility, ask about paying for a few extra walks or runs.
Before you drop off Fido at the boarding facility, make sure he'll eat his food without any additions. If you like to feed Fido treats, feed him pet treats, not table scraps. Then send a package of those treats with him to the boarding facility.
If your pet has a favorite toy or bed, send it along to the boarding facility, unless the facility doesn't separate the animals. If the animals are kept together in an open area, you pet's toy or bed may cause problems. Your pet, like a small child, may not want to share, and the other pets, like children, may try to force him to share. In an open boarding situation everything is community property. You can still send along special treats, but understand that the other animals will probably get some as well.