Ask a Dog Vet and Get Answers to Your Dog Health Questions
I am sorry to hear you are worried about your Labrador. My name is Rebecca. I am a veterinarian and will do my best to help.
Pen G is not a good antibiotic for the type of bacteria that can cause diarrhea and is not anything I would recommend. If you want to try it, the dose is about 1 cc per 20 pounds, but I don't recommend it and the injections are painful.
How much Lomotil have you been giving? It is not a great diarrhea drug for dogs either.
You can try Loperamide (Imodium) or Pepto Bismal at half the dose for adults, twice daily.
Is she eating, and drinking normally?
I would try the Pepto or Imodium rather than the PenG.
Let me know how she is, and what else I can help with or answer.
How is she doing? Can I help with or answer anything else?