A boarding stay is full of new sights, new smells and more activity than most dogs get at home. That is why the first two days back are mostly about rest and routine.
Why he may be so tired
Dogs at a kennel run, sniff and watch more than usual, and they sleep less deeply in a busy place. At Happy Paws the staff compare it to summer camp: more going on, then a tired dog at home. The tired-dog question page covers this. A long sleep the first evening is normal.
Food and water
Offer fresh water right away, but let a very thirsty dog drink in small amounts rather than gulping a full bowl. Feed a normal portion at the usual time. If your dog ate the kennel's house food, which is grain-free kibble plus wet food, mix his own food back in gradually if there was a change, and watch his stool. Loose stool for a day can follow any change in routine or food; if it lasts, call your vet.
The coat and the bath
Happy Paws is a country kennel on about 10 acres with a grass field, so your dog may come home dusty or grass-stained. If you want a clean dog at pick-up, tell the staff your arrival time so bathing and drying are finished when you get there, and ask about the bath price. Check paws, ears and skin for seeds and burrs, a common thing in dry Northern California grass.
What to watch for
A mild cough after any stay around other dogs is worth noting. AKC health guidance on kennel cough describes a harsh cough that can appear 2 to 14 days after exposure, with most dogs recovering within one to three weeks; call your vet if your dog stops eating, has a fever or the cough worsens, and keep him away from other dogs while he coughs. Vomiting that repeats, pale gums, trouble breathing or a swollen belly need a vet right away.
See the kennel cough symptoms page for more on what is normal and what is not.
Settling back in
Keep walks calm and short for a day. Skip a trip to the dog park the first day. Let him sleep and return to his normal bed. If he follows you from room to room, that is affection and relief, and it fades quickly.