How do I prepare multiple dogs for a long 3-day road trip?

That sounds like a lot of fun for Sara and the rest of the crew!!! I would definitely recommend to get all the dogs use to each other well before the trip, that way if there are some aggression issues or other problems, these can be addressed right away. It would be a good idea to get all the dogs use to long car rides. If some of the dogs don't travel well, you can talk to their vet about sedatives/anti-anxiety medications. Also you will need to make sure that all pets are up to date on vaccines as well as flea AND heartworm prevention. I recommend to use a more complete heartworm prevention such as Interceptor or even a combo product like Trifexis. These products prevent heartworm and also have activity against 3 intestinal worms. This is smart since the dogs will be traveling and thus have higher exposure. Lastly, you should carry with you the vaccine records and to be safe, get an interstate health certificate on each one. Best to work out any kinks well in advance and prepare for any legal situations. Have fun and thank you for using Petco Pet Education Center, formerly Petcoach.