I am sorry to hear you are worried about your dog. I am a veterinarian and will do my best to help.
Has she had this runny nose and discharge since October 2014?
I am sorry an expert has not helped you sooner. I just came online and saw your question.
A runny nose is not usually seen with heartworm. I agree, it does indicate something up in the nose, allergies, or a nasal infection. If she is aspirating ash into her nose, that could cause a chronic discharge. I would also expect her to be sneezing
, if she is getting ashes up into her nose.
Is the discharge clear, or is there any blood in it? It is from both nostrils, or just one?
If I could, I would collect some discharge and examine it under a microscope. That should tell me if this is an infection requiring antibiotics, or if it is due to irritation or if there is some other reason for the discharge. We do see dogs get tumors
(benign or cancerous) in the nose, but usually when that is the reason, the discharge is from one nostril, and often there is blood in the discharge.
If looking at the discharge microscopically does not tell me the reason for it, I would next look up the nose with a scope.
Is she sneezing or coughing at all?
Let me know what other questions you have. Rebecca