Have cats. Would it be risky to adopt a 1-year-old German Shepherd?

I am wanting to adopt a GSD from a pound but I have 2 cats as of now. Would it be risky to adopt the GSD? Should I look for a puppy? One of my cats ignores dogs and minds his own business. My other cat is skittish and will hide from dogs until he gets used to them, usually takes about a couple weeks. He will hiss and lightly smack with his paw but never attacks.