2- Time the baths.
Stay on schedule with giving baths every 3 weeks. You may think that baths are not needed as much in the winter especially if your Chihuahua is inside a lot more than during warm weather, however baths are not just to remove dirt; they are to rid the skin
and fur of excess body oils that are being constantly produced; at the 3 week mark there is enough that it can start to smell and tiny furs that shed off trap this near the skin's surface, making it even worse.
3- Use a leave-in.
If there were any one element that was needed for winter care to keep a Chihuahua's coat healthy, it is a quality leave-in spritz. (This is also an important grooming element in the summer as well, due to the sun). A good spritz will do several things:
1. Protect the fur from dry air - It will create a barrier from winter's outside elements and from dry air that is commonly indoors in the winter as well.
2. Prevent the coat from getting contact friction damage and static.
3. Seal the strands to prevent split ends.
Look for a quality spray that is light yet offers protection and as a plus, you may want to choose one that also emits a light, fresh fragrance to keep your Chihuahua smelling nice. This should ideally be applied once per day - You will want to mist the coat, holding the bottle about 5 to 6 inches away and then distribute it from roots to ends with a small soft bristle brush.
Take care to not overdo it; you only want to lightly coat the fur, not drench it.