Is a young or an old dog the perfect addition to your loyal friend and is there a breed that you shouldn't consider? These questions are as important as they are legitimate. First to the first point.
How old should the second dog be?
A puppy is best suited to a young dog as a second dog? Not necessarily. Anyone who has raised a puppy knows that it does a lot of work. A young dog usually has fuzz in his head and teaches his pranks to the puppy. That is not exactly the ideal prerequisite for peaceful coexistence.
In addition, dogs change significantly in their first year of life and are particularly different in terms of development. This also does not make the education of two young dogs easier and is only advisable to experienced owners. So it is best to only bring a puppy on board if your dog is confidently and perfectly trained and you can rely on him. Dog training becomes much easier if there is already a dog with "good behavior" in the house, or if you have a slightly older, seated dog with your young dog.
Cuddle friends: puppies vs. cement
Which dog breeds suit your pet?
You should opt for similar breeds if possible. Dogs of the same breed have similar needs in terms of play and exercise and are roughly the same size. So there is no danger that one is physically superior to the other. This benefits friendship.
However, the animals should not be too similar if they have a strong character. For this it is important to get to know the second dog a little beforehand or to get as much information as possible from its previous owner. If you have a dominant dog at home and bring such a dog into the house, trouble is inevitable. Tireless struggles for the rank order or a chaos team that makes the neighborhood unsafe for two is certainly not in your interest.