How much penicillin can a dog take? A Comprehensive Guide

Overview of Penicillin G for Dogs and Cats

  • Penicillin G, common vet prescriptions known as Crystacillin® or Flo-Cillin®, is an antibiotic used to treat and prevent bacterial infections in dogs and cats. This is a natural penicillin and is cultured from the bacteria Penicillium chrysogenum.
  • As with similar penicillin drugs, penicillin G kills bacteria by inhibiting production of the bacteria cell wall. Other related drugs include ampicillin, amoxicillin, and ticarcillin.
  • Many bacteria develop resistance to penicillin G.
  • Penicillin G is a prescription drug and can only be obtained from a veterinarian or by prescription from a veterinarian.
  • The duration of administration is harder to determine. In some cases Amoxicillin may be used to prevent infection after cleaning — trauma to the gums may allow an infection to develop. To prevent infection, a short course of treatment (approximately three days) may be all that is needed. In cases of severe gum disease (periodontitis), then a longer course of treatment would be needed, and four weeks of treatment would not be unusual.

    Best of luck to you and your pet! Michael Stone DVM, DACVIM (Small Animal Internal Medicine) Cummings School

    So I can offer the correct dosage of Amoxicillin, but the length of therapy really depends upon the severity of the condition being treated. The correct duration of therapy for your pet is best determined by your veterinarian. A 10-day course of treatment does not sound unreasonable and I wouldn’t be worried about any long-term harm from that length of therapy.

    The dose of Amoxicillin is based upon the dog’s weight. The correct dose is 5 milligrams per pound of body weight twice daily. So if your dog weighs 10 pounds, the dose would be 10 pounds x 5 mg/lb = 50 mg twice daily. The dose may be increased to 10 mg/lb twice daily in severe infections. Because Amoxicillin is supplied in 50, 100, 150, and 200 mg sized tablets for dogs, veterinarians will often round the dose to the closest 50 mg.

    Yesterday my dog had his teeth cleaned by a vet, who has prescribed 100 milligrams of Amoxicillin twice a day for 10 days. I am concerned about giving him too much Amoxicillin over that period of time. What is the correct dosage after teeth cleaning? Barry S. Zisman Frisco, Texas

    Brand Names and Other Names of Penicillin G

  • This drug is registered for use in humans and animals.
  • Human formulations: Penicillin G Potassium® (Apothecon), Pfizerpen® (Roerig) and various generic preparations
  • Veterinary formulations: Crystacillin® (Solvay), Flo-Cillin® (Fort Dodge), Crystiben® (Solvay), Dual-Pen® (TechAmerica) and various generic preparations
  • Antibiotics dosage for dogs and puppies

    Naturally-occurring penicillin was the first antibiotic to be discovered. Many modified forms of penicillin are now available, but the natural form is still in use today.

    Penicillin has a limited spectrum of activity, and many types of bacteria have developed resistance to this drug. For these reasons, veterinarians typically prescribe penicillin when they are reasonably sure that it will be effective against a particular infection or in combination with other drugs.

    Penicillin is usually given by injection. Some types can be injected into a vein while others must be injected into a muscle or under the skin. An oral form is available but is rarely prescribed. It works best on an empty stomach but may be given with food if stomach upset occurs.

    Penicillin kills susceptible bacteria by disrupting their cell walls and by preventing them from building a functional cell wall when they reproduce.

    Store oral tablets and powders in a tightly sealed container at room temperature and away from bright light and moisture. Once the powder has been mixed with water, it should be refrigerated and disposed of after 14 days. Liquid penicillin for injection should be refrigerated. Some forms should be discarded after 24 hours if left at room temperature and after seven days if refrigerated. Follow the storage directions provided on the label.