TheFork users who ate in Saint-Malo have said really good things about Le Saint Placide, Monsieur Madame and L'Absinthe. Maybe you should give them a try!
Some of the more popular Cellar restaurants where you can go with your pets in Saint-Malo according to TheFork users include:
Le Saint Placide, with a 9.6 rating
Monsieur Madame, with a 9.5 rating
L'Absinthe, with a 7.9 rating