Hi Rachael, I'm Dr. Deb. I will do my best to assist you today.
I'm so sorry for these problems with Joey but it's good that you're available to help and so knowledgeable.
1. Yes, I would definitely recommend an antibiotic. Clavamox or Cephalexin are excellent choices for a bite wound.
The dose of Clavamox for an 8 lb dog would be 62.5 mg twice a day.
The dose of Cephalexin would be 150 mg twice a day.
You probably know to give antibiotics with food, is possible.
I usually give oral antibiotics for 10-14 days or longer if needed.
I feel obligated to tell you that it would be illegal for me to advise you to use a drug for Joey which was prescribed for another dog or for a human but I can tell you dosages as I just mentioned of acceptable drugs which would be useful in this context.
2. Subcutaneous injections are not usually needed for bite wounds since improvement is usually seen fairly quickly once oral ones are started.
3. Erythromycin eye ointment is also a good choice but make sure that it doesn't have any steroid in it since this could worsen the situation if the cornea has been scratched or injured. Dosage would be 3-4 times a day for at least 7-10 days.
4. If you have access to topical Atropine, this would also be advisable. Dose would be twice a day for 2-3 days and then discontinue if the eye shows significant improvement. This drug would help with pain and spasm control if the cornea has been scratched. The pupil will dilate and will remain so for about 12-24 hours after the drug has been stopped...which you may already know.
5. You could give Aspirin at a dose of 10 mg/lb twice a day for inflammation and pain control. The dose for an 8 lb dog would be 81 mg twice a day. Give with food to avoid stomach upset.
6. Do the best you can to clean the area of the bite wound; I'd recommend dilute betadine or iodine to the color of weak tea. Trimming as much hair as possible is good as well, if he will let you.
If he's drinking water, then you might mix canned food with water in a blender to see if he will "drink" his meals. You could also offer human baby food but avoid those with onion or garlic in them.
You could take his temperature although I suspect that it might be elevated reflecting the infection he has. Normal is between 100 and 102. 5
I hope this helps and that Joey will feel better soon. Deb