6 month old hen acting subdued and not interested in food.

I'm sorry that your question wasn't answered in a timely manner. You deserve the courtesy of a response although I fear it's likely to disappoint you. I have advanced training in avian medicine and must tell you that Blanche's appearance and behavior - while significant - aren't symptoms pathognomonic for any one disorder. Her purple comb, however, indicates cyanosis - poor oxygenation of her tissues and that, in turn, suggests cardiopulmonary disease.

In avian medicine, there's rarely one cause of a condition, so we usually begin with a list of differential diagnoses and use lab tests and physical exams to differentiate. With this in mind, your best course of action is to reach out to your county-extension poultry personnel or veterinarian for help in differentiating the various causes of what you're seeing. Veterinarians can perform a physical exam and run diagnostic tests, including X-rays, to distinguish between the various etiologies. Please see here: www.aav.org

It's best to approach the diagnostic process with a clear sense of the bird's financial value to your operation. Although some services might be available free of charge through a county agency or land-grant extension office, the expense of some diagnostic tests and treatments can add up quickly. While it’s always worth your time and money to identify a bacterial or viral infection that could potentially impact more than one member of the flock, this might not be the case with a condition that only affects one hen.

Please respond with further questions or concerns if you wish.