A black dog with a white patch on its chest is not an indicator of good or bad luck. As long as the dog is healthy, it is perfectly fine to keep as a pet.

Firstly, abandoning a dog with white chest markings is not acceptable. Some people believe, influenced by folklore, that a dog with white chest markings is unlucky and brings misfortune. They then abandon the dog. This is wrong; owning a dog with white chest markings doesn't necessarily bring bad luck, but abandoning any pet is certainly a negative action. Secondly, individuals whose Chinese zodiac signs clash with dogs might consider not adopting a dog with white chest markings. According to the Chinese zodiac's compatibility theory, those born in the years of the Ox, Dragon, or Goat are considered incompatible with dogs. Thirdly, when keeping any dog, it’s vital to keep the environment clean, and promptly clean up its waste and loose fur to maintain the home and avoid negative impacts on personal finances.

Black dogs and yellow dogs are traditionally considered to be more auspicious for attracting wealth. Black dogs are believed to ward off evil spirits, and owning one for a long time can bring good fortune and dispel misfortune. Yellow dogs are classic symbols of prosperity, believed to attract and accumulate wealth. Additionally, dogs with white markings on their belly, a white tail with a white patch around their waist, or pure white paws, are also considered good for attracting financial luck.Source:5D Pet World