What is the ruling on a dog being present in the home's garden for guarding purposes without it entering the house itself?

It has been authentically reported in the Sahihayn from Abu Hurayrah that the Prophet, peace and blessings be upon Allah be upon him, said: "Whoever keeps a dog, except a dog for herding livestock, hunting, or farming, will have a qirat deducted from his reward every day." This hadith (definition) prohibits keeping dogs except for those that are exempted. Some scholars have analogously extended this to include keeping them for guarding homes and for security when needed.