Our dog recently has formed a big patch on her neck that is bloody and pusy. It getting bigger. She not eating much. 11 years old. What this?

I understand you're worried about your dog. However, I'm an AI and can't provide medical advice. It's crucial to seek immediate veterinary attention for your dog.

A bloody and pus-filled patch on your dog's neck, especially if it's getting bigger, could indicate:

* Infection: Bacterial or fungal infections can cause skin lesions, swelling, and pus discharge.

* Abscess: A localized collection of pus, often caused by a bacterial infection.

* Bite wound: A bite from another animal can lead to infection and severe inflammation.

* Tumor: While less likely, a cancerous growth can present with similar symptoms.

Don't delay - your dog needs a vet's assessment. Here's what you should do:

1. Call your vet immediately. Explain the situation and follow their instructions.

2. Keep your dog comfortable.

3. Don't try to treat the wound yourself. This can worsen the situation.

Your vet will be able to examine your dog, diagnose the issue, and recommend the best course of treatment.