It is usually understood that a service dog needs to be 'house trained" in all public places but there is so much more to it than that. The dog needs to have both urinating and defecating under stimulus control so you can control where and when he will go.
Do dogs learn to hold their pee?
Typically, a puppy can control their bladder one hour for every month of age. So if your puppy is 2 months old, they can hold it for about two hours. Don't go longer than this between bathroom breaks or they're likely to have an accident.
Has anyone trained their dog to use the toilet?
Although dogs are not as fastidious about their potty habits as cats, they can be trained to use the toilet too, and with large dogs that do not require steps or special adaptations to reach the toilet, the training process can be simpler. At least your big dog should not be afraid to fall in the toilet!
More useful articles on a similar topic 👇
Are French bulldogs harder to potty train?What is the best age to train a dog to be a service dog?