Must dog wear muzzle on train in France?

According to the SNCF’s own rules, yes, dogs should be muzzled on trains unless they are little dogs travelling in a bag (!) or a sealed case. An exception is made for guide dogs.

You may be interested to know that you are supposed to buy a ticket for your dog – for a small one in a case on your knees or at your feet, this is €7, or for larger dogs (which should travel at your feet), the price is half a person’s second class ticket. Guide dogs go free.

Otherwise the only legal restrictions concern “dangerous dogs” - those of “type 1” may not travel on public transport at all, whereas “type 2” breeds may do so with a muzzle and lead.

The former includes non-pedigree dogs similar to pitbulls, mastiffs or tosas, and the second includes pedigree Rottweilers, tosas, Staffordshire terriers and American Staffordshire terriers.