My rule of thumb has always been if it feels chilly enough for me to wear a sweater/jacket, then they need one too. Also, if it's below 30 degrees, they'll only go out to potty and I won't do the usual long walks. And if it's REALLY cold (single digits), they stay indoors.
__________________  Snickers & Baxter Until one has loved an animal, part of their soul remains unawakened. |