Can a 10-pound chihuahua have penicillin and how much?

It is best to consult with your veterinarian about the exact dosage and frequency for your specific chihuahua. However, here is a general calculation:

Veterinarians typically dose penicillin at 10 to 22 mg per pound (22 to 48.4 mg/kg) every 6 to 8 hours. In other words, a 10-pound (4.5-kilogram) chihuahua might receive between 45 and 99 milligrams, once or twice a day.