Guinea-pig carriers can be very small and often open only from the top so poor piggy can't walk in but has to be loaded in and out like a parcel. Also I'm never happy about how safe it is to pick up this type of piggy 'handbag' knowing that if those plastic clips fail the bottom will suddenly drop out with no warning! So I transport mine in to and from the vet in a cat-box which has a wire door at the front. Two pigs can move around comfortably in here. Cat-box comes out a few days before the trip and sits open in the run (with food in and a water bottle on the door) so they can go in and out and get used to it. That way, when the time comes to transport, they recognise it as part of their territory and feel more comfortable in the car. After the vet has finished looking at 'the patient' they always run back into the cat-box so they do see it as a safe place. I also use it in the grass run in the garden as a hidey.
I have a light blanket to cover it in the car in case of cold weather/hot sun. I always strap it into a seat because if you put it on the floor there are a lot of scary vibrations from the engine and the road surface, and it is noisier and smellier down there. Sometimes I use a cushion or folded towel so it can sit straight because some cars have seats that slope a lot. And I don't have the radio on too loud - I just put it on low with the speaker switched off on piggy's side (they usually go in the passenger seat in my car). There is always plenty of hay, a few pellets and the water bottle there.
Have a nice trip! ☺
I found that they coped really well, eating, roaming around and sleeping as normal.
