A guinea pig is a creature of routine. A stay away from home goes best when the food, the hay and the hideaway all stay exactly the same.
The vitamin C rule
The Merck Veterinary Manual explains that guinea pigs cannot produce vitamin C and must get it from their diet. Vitamin C in pellets fades over time, so use a fresh bag and not one that has sat for months, and do not swap in rabbit pellets. Pack the pellets your guinea pig already eats, plus the fresh vegetables he gets at home, in labeled bags. Write the daily amounts on a card instead of explaining them aloud.
Hay and chewing
Unlimited good-quality grass hay such as timothy or orchard grass is the main food, according to the Merck manual. It keeps teeth worn down and the gut moving. Send plenty, because a guinea pig that runs out of hay can slip into trouble quickly. Alfalfa hay is meant for young, pregnant or nursing animals; keep your usual hay.
The setup
The kennel may ask you to provide the cage for small pets. Bring it clean, with a hide house, a water bottle that works, a heavy food bowl and the bedding you normally use. Guinea pigs hate being alone in an exposed cage, so the hide house matters. Label every item with your name and phone. Keep the cage out of drafts and heat. Ask where small pets are kept and how that area stays comfortable in July, when the Central Valley often passes 100 degrees.
Read the guinea pig boarding page and the small pet packing list.
Travel day and the return
Carry your guinea pig in a small, ventilated carrier lined with bedding and hay, with the air conditioning on. Never leave a small animal in a parked car. When you pick him up, expect a bit of shyness. Watch appetite and droppings for a day; a guinea pig that stops eating, is hunched or has runny eyes should see an exotic-animal vet the same day.