1 cc per 20 lbs every 48 hrs subcutaneously. Its hugely important to get make sure that your dog gets exactly the right dose of medicine at the correct time intervals. Dog Medications Dosage Penicillin Dosage For Dogs Dog Medicine Pet Medications Medication For Dogs 1 In both dogs and humans antibiotics work by attacking and killing the bacterial infection while preventing it from growing any further. . 300000 units per ml. 5 mg per lb every 8 hrs. Dog medications dosage requirements are generally calculated by weight and measured in mg of medicine per pound of body weight. Many people know that you can give your dog penicillin orally to aid certain infections. How often can you give a dog a antibiotics. But antibiotics only work on bacterial infections which is why your doctor wont prescribe them to you for a basic cold or flu which is caused by a virus. Antibiotic to fight bacterial infections. It is cru...