Maybe she has a doggie cold. Is it all the time? Was she just out in the cold? If not maybe you should take her to the vet just to be safe.

To specifically answer your question, it is coming out, because it is there and needs to come out! The actual question is actually several questions. What COLOR is it, is it thick and cloudy, or thin and runny. Has your dog had (at anytime) all of it's puppy shots. There is some controversy as to if you need to vaccinate yearly once ALL of the puppy shots have been given. After several years of regular vaccines, I no longer do so. I do, however, continue to dose my dogs every six months with a Homeopathic Remedy of the 4 n 1 drops to ease my own mind that they are protected. Blood tests have shown that MOST DOGS who were vaccinated as puppies...with all of the supposedly needed vaccines, RETAIN sufficient levels of the protection as long as 12 to 14 years without further vaccines being given. So, if your dog EVER had her shots, she should still be covered. However, if this is a green or yellow discharge, thick in nature, it shows possible infection, and also that it has been in the brewing stage for a good while...the yellow or green color "says, this is not brand new." If it is white or clear, it COULD BE allergies, or a cold of some type. Your most urgent need is to take your dog's Temperature which should be between 100.4 and 102.2. You take it with a rectal thermometer, applying a bit of olive oil or petroleum jelly. You will need someone to help restrain the dog, gently so as not to cause the dog stress which only makes them move about more. Holding the tail off to the side and gently inserting the thermometer about 1 inch into the rectum, holding it still, and angled so that the bulb is against the rectal wall. Wait 30 seconds, remove it and read it. (disinfect before returning it to the case.) If your dog is running a fever, you need to take her to the Vet. If she has other things going on to make her look "off color" vomiting, less interest in food or water, or drinking more water than normal, no interest in play, change in her stools...texture or frequency, coughing, sneezing, sudden weight loss or gain...TAKE HER TO THE VET. REMEMBER NO ONE HERE can actually SEE your dog. YOU are the best judge as to knowing if she appears not herself! Better safe than sorry.