Dog First Aid Kit/Pet First Aid Kit - Vet Approved - 45 Premium Items (Charlie the vet)  https://amzn.eu/d/eERYTcm (link) 

Water & water bowl 

Towels

Extra leads 

Muddy daddy pressurised cleaner with brush 

A comb/brush 

Slip leads (emergency use)

Secure clips for car/van travel 

Treats (agreed before hand or use what they're used to) 

Dog anti bac wipes 

Poo bags (obvious but still) 

Soft Muzzle (for emergency use only incase of accident and they're injured/distressed)