The life expectancy of a very young puppy with a bad heart disease (like congenital defects) is not good. In their early days or months they actually compensate very well because they are growing and can adjust. However, as dogs reach maturity (6 months in her case) they will begin to to DE-compensate and will begin to show serious symptoms.
It is very difficult to tell you want you will see - impossible in fact. We do advise you see your veterinarian to at least determine the cause. Armed with this knowledge your veterinarian can give you a good idea of a prognosis - or perhaps life expectancy.
Such a problem is grave and rarely is there a "cure" or much good news. We have all seen these cases and can imagine what you must be feeling. Please talk with your veterinarian and let us know what you determine.
thank you so much for your time sir
could you tell me if there is dogs that live a good life knowing they have in large heart and medicine i might give her or any advice
You are right to be concerned in one so young/so small. Hopefully your veterinarian has suggested or moved ahead with the tests necessary to determine the exact cause of the enlarged heart. Among these, ultrasound (sonogram) would likely be most helpful. With that information, it will then be possible to determine what can be done.
Low sugar is a common finding in young/ill/stressed animals and can be corrected with regular eating/or fluids and dextrose supplementation intravenously if not eating.
You are hopefully working closely with your veterinarian to quickly move ahead in the diagnostic process. I can only wish you and your pup well, as a situation like this requires a closer relationship than this forum can provide. Please follow your doctor's recommendation as quickly as possible.