Penicillin G
Also known as: Bicillin C-R, Masti-Clear, Permapen, Pfizerpen, Go-Dry
* **Administration:** Give oral penicillins on an **empty stomach** (1 hour before or 2 hours after a meal) to maximize absorption. If your pet experiences stomach upset (vomiting, loss of appetite), you may give it with a small amount of food. * **Compliance:** It is critical to **complete the entire prescription** exactly as directed, even if your pet seems completely better. Stopping early can lead to resistant infections. * **Allergic Reactions:** Watch for signs of an allergic reaction, such as facial swelling, hives, rash, or difficulty breathing. Contact your veterinarian immediately if these occur. * **Injection Sites:** If your pet is receiving injectable forms, the injection site may become sore or swollen.
Dosage must be set by your veterinarian for your specific pet. Never give human medication or another pet’s prescription without veterinary guidance.
What it is used for
- Soft tissue, systemic infections
- Soft tissue infections
- Orthopedic infections
- Resistant organisms (Actinomyces)
- Susceptible infections
- Susceptible infections
- Susceptible infections
- Susceptible infections
- Susceptible infections
- Clostridial abomasitis and enteritis in calves
- Bovine respiratory disease complex
- Susceptible infections
- Susceptible infections
- Susceptible infections
How it is given
Possible side effects
- Hypersensitivity reactions (anaphylaxis, urticaria, rash)
- Gastrointestinal upset (anorexia, vomiting, diarrhea) with oral use
- Procaine toxicity (CNS excitement, seizures) in small birds and horses if inadvertently given IV
- Pain or tissue reaction at IM injection sites
Cautions & contraindications
- Known hypersensitivity to penicillins or cephalosporins
- Intravenous administration of Procaine or Benzathine suspension formulations
- Oral administration in horses and hindgut fermenters (rabbits, guinea pigs) due to risk of fatal dysbiosis (unless specifically indicated, e.g., calves with clostridial enteritis)
- Use cautiously in small birds as procaine penicillin may cause procaine toxicity. Do not use oral penicillin therapy in horses for systemic infections (e.g., botulism). Ensure repository forms (procaine/benzathine) are never administered intravenously. Monitor for hypersensitivity reactions. High doses of Penicillin G Potassium given rapidly IV can cause hyperkalemia and cardiac arrhythmias.
Drug interactions
- Bacteriostatic Antibiotics (e.g., Tetracyclines, Macrolides): May antagonize the bactericidal activity of penicillins, which require actively dividing cells to be effective.
- Aminoglycosides (e.g., Amikacin, Gentamicin): In vivo synergy against certain bacteria; however, physically incompatible if mixed in the same syringe or IV line (inactivation of the aminoglycoside).
- Probenecid: Competitively inhibits renal tubular secretion of penicillins, significantly prolonging their half-life and increasing serum concentrations.
Frequently asked questions
What is Penicillin G used for in pets?
* **Administration:** Give oral penicillins on an **empty stomach** (1 hour before or 2 hours after a meal) to maximize absorption. If your pet experiences stomach upset (vomiting, loss of appetite), you may give it with a small amount of food. * **Compliance:** It is critical to **complete the entire prescription** exactly as directed, even if your pet seems completely better. Stopping early can lead to resistant infections. * **Allergic Reactions:** Watch for signs of an allergic reaction, such as facial swelling, hives, rash, or difficulty breathing. Contact your veterinarian immediately if these occur. * **Injection Sites:** If your pet is receiving injectable forms, the injection site may become sore or swollen.
Is Penicillin G safe for my pet?
Dosage must be set by your veterinarian for your specific pet. Never give human medication or another pet’s prescription without veterinary guidance.
This article is for general education and is not a substitute for professional veterinary advice. If your pet is unwell, please consult a veterinarian.
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