Penicillin for Cats: Applications, Dosage, and Potential Side Effects-Catpedia
Penicillin is an antibiotic derived from Penicillium fungi and falls under the beta-lactam class of antibiotics, primarily used in cats to treat bacterial infections. It works by disrupting the bacterial cell wall, effectively killing the bacteria. As one of the oldest antibiotics available, penicillin has been essential in veterinary medicine for its effectiveness and relative safety when used properly.
Below is an overview of the uses, dosage, and side effects of penicillin for cats.
Uses of Penicillin for Cats
Penicillin is prescribed to treat a range of bacterial infections in cats. It is especially effective against gram-positive bacteria like Staphylococcus, Streptococcus, and Clostridium species, but can also address certain gram-negative infections. Common infections treated with penicillin include skin, respiratory, urinary tract, and gastrointestinal infections. Additionally, it can be administered to prevent infections in wounds or post-surgery. Veterinarians may also use penicillin for more severe infections, such as septicemia (blood poisoning) and peritonitis (inflammation of the abdominal lining).
It’s important to note that Penicillin V, which is approved for human oral use, does not have FDA approval for animals. However, veterinarians can prescribe human-approved medications for pets in specific cases, known as “extra-label” or “off-label” use, which is the use of a medication outside its approved guidelines. Your veterinarian will determine if this is appropriate for your cat’s condition.
Dosage of Penicillin for Cats
The following information provides general guidance but should not replace personalized advice from your veterinarian.
The type and severity of the infection, the cat's weight, and general health all affect how much penicillin is prescribed for cats. There are several types of penicillin, such as injectables, oral pills, and liquid suspensions. Penicillin G, a widely used injectable version, is usually given two to six times a day at a dose of 10,000 to 25,000 units per pound of body weight. Crystacillin®, Flo-Cillin®, Crystiben®, and Dual-Pen® are some of the brand names that Penicillin G is sold under. Oral penicillin is usually administered once daily at a dose of 5 to 10 milligrams per pound of body weight.
The treatment duration usually spans seven to 14 days, though in some cases, longer treatment may be required. Completing the full antibiotic course as prescribed by your vet is essential, even if your cat appears to have recovered. Stopping treatment early can lead to antibiotic resistance, making future infections harder to treat.
Proper storage is important for penicillin. Oral tablets should be stored in a cool, dry place at a controlled temperature between 68-77°F, away from sunlight. Injectable solutions may require refrigeration. Always check the label or consult your veterinarian for specific storage instructions.
Side Effects of Penicillin for Cats
Although penicillin is generally safe for cats, some may experience side effects, usually mild, though more serious reactions are rare. Possible side effects include:
- Vomiting
- Diarrhea
- Loss of appetite
- Allergic reactions
If your cat shows signs of an allergic reaction, seek veterinary assistance immediately. Less common side effects may include behavioral changes or seizures, though these are extremely rare. Long-term or repeated use of penicillin may disrupt normal gut flora, potentially leading to secondary infections.
Penicillin may interact with other medications, including certain antibiotics and drugs like methotrexate and probenecid. Be sure to inform your veterinarian of your cat’s complete medical history, including any past allergic reactions to penicillin or other antibiotics, as this may impact medication choice. Additionally, take extra care when administering antibiotics to pregnant or nursing cats.
If you miss a dose of penicillin for your cat, consult your veterinarian. Generally, they may recommend giving the missed dose as soon as possible, unless it’s nearly time for the next scheduled dose. In that case, you may be advised to skip the missed dose and continue with the regular schedule to avoid doubling doses.
