Dogs respond to the vowel sounds more than the consonants. If you change the name but keep the same (or similar) vowel sounds, chances are it’ll be completely seamless.
Many of the names that shelter pets have are not the names the grew up with. If the pet was surrendered by the owner who supplied the name when the pet was brought in and if that name was not totally inappropriate, than the pet probably is using its “given” name.
There is usually a surrender sheet filled out by the person who brings the pet in. Shelters that I have adopted from usually let you see this, a copy of it may even accompany the pet.
Many pets arrive at shelters without any knowledge of their past/history.
If the pet is using a name it got when it arrived at the shelter, it probably has not recognized it yet. You can change it without difficulty, to anything you think is most appropriate.
New life, new name, new home, and happiness forever in the new forever home.
The dog will need to adjust to you, your family, your schedule, and a new home. During that period they will surely adjust to a new name if you want to give them a new name. Learning a name is no harder than learning a command such as “sit” or “stay”.
In essence, it doesn’t really matter. But it could be a positive thing, sometimes the old name can carry with it past traumatic experiences and fears for the dog, a new name could be a fresh start and eleviate any chances of this being the case, when the history is unknown.
9 times out of 10, the dog will respond to a new name it might just take some time, especially for older dogs. Keep in mind that dogs pay attention to the context, intonation, body language and number of syllables. If you whistle in a specific way every time, say anything similar with the intonation of calling your dog, they will probably run or walk towards you.
Dogs are very smart and socially observant. If you call them something else when you first take them in, in due time they will adjust. Only downside to this and which is a small probability given the circumstances, is a dog getting confused when they hear their old “name”. Which isn’t a big deal, in my opinion, so long as no one is still actively calling them by their old name while you are trying to get them used to their new name.