Friend, I am sorry Ostara is not feeling well, I am sure this must worry you. In response to your question, listless and decrease appetite are very non-specific symptoms and can be related to many different medical conditions that affect dogs. As far as her breathing this could be an indication of an underlying cardiopulmonary disorder or simply being weak from being systemically ill. If you are seeing a vaginal discharge, this is important because it could be an indication of a uterus infection (pyometra) which can cause all of the symptoms that she is showing.
Unfortunately, there is not much I can recommend for you to try at home that would have any significant therapeutic benefit, I am sorry. In this case, Ostara will need a hands on examination, blood work (chemistry profile & CBC), x-rays and urinalysis as an initial screening test to determine the exact underlying cause. Treatment will be based on clinical and diagnostic findings. I would strongly recommend having her checked by your family veterinarian first thing in the morning. If you have access to ER vet I would have her checked tonight, especially if you are seeing a vaginal discharge, important to rule out a pyometra (infection of the uterus).
I realize that this answer may not be entirely to your liking, and I regret being the bearer of information that you really don’t want to hear. But it would be unfair to you and unprofessional of me were I to provide you with anything less than truthful and honest information. I hope you understand.
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