How Much Penicillin to Give a Cat? Know the Truth Right Now

Have you experienced being extremely worried about your cat’s overall health condition? Here’s a bit of bad news – our beloved feline friends are also just as susceptible to illnesses just like us. No matter how much we love and take care of them, they could still get sick once in awhile.

If you are already able to tell when your cat is sick or in excruciating pain, then you are likely to research how much penicillin to give a cat. Allow me to help you on this matter as I have done my own research on the said medication. Let’s take a closer look at how we can help our cats to fully recover more easily with the help of medication and proper administration.


How Much Penicillin to Give a Cat? Know the Truth Right Now

What Is Penicillin and How Does It Really Work?

Penicillin has been around for decades and was first introduced in the world of medicine back in the 1940s. This was when the so-called era of antibiotics emerged and was recognized as one of the biggest medical advances. Large-scale production of the said medicine was attributed to the United States during the Second World War.

However, it is important to emphasize that the said medicine was first discovered by the renowned Scottish biologist and professor, Alexander Fleming in 1928. Back then, he was a Professor of Bacteriology at London’s St. Mary’s Hospital.

So, how does penicillin work? It works by killing bacteria and zapping their ability to synthesize or build cell walls. When penicillin is administered, it allows the bacteria to lengthen, but not to divide and multiply. This then prompts their cell walls to rupture.

When Was Penicillin First Tried on Animals

Penicillin was first tested on animals in 1911. Ernst Chain and Howard Florey performed the test using eight mice as subjects. The mice were injected with the lethal amount of bacteria and half of them were then given penicillin.

The four mice that were administered with penicillin recovered and lived. On the other hand, the rest of the mice died. The astounding result of the test became instrumental in proving that penicillin was indeed an effective antibiotic that can be used to treat a severe bacterial infection.

Penicillin and Cats


Penicillin G is one type of penicillin that is often used to prevent and cure bacterial infections in both cats, dogs, foxes, rabbits, and mink. This penicillin is naturally cultured from the bacterium called Penicillium chrysogenum. Note that this particular medicine is only for the veterinary purpose and can only be obtained with a prescription.

Generally, the Penicillin G is administered to treat conditions such as bacterial infections linked to pneumonia, tracheitis, and bronchitis. In addition, it also an effective medicine that helps treat a skin infection, wounds, bladder infection, and tooth abscesses in cats.

It is crucial to remember that you cannot use this medicine for infections caused by parasites and virus. This is why checking with the veterinarian and having your feline pal monitored and tested are two of the most important steps prior to the selection of the right medicine to give.

Dosage and Administration

The dosage for penicillin depends on the body weight of your cat. Generally, a 6000 i.u per kilogram or 1 ml/50 kg is the basic formula used. The dosage should then be increased to 12000 i.u. up to 18,000 i.u. per kg when the infection is deemed serious.

For cats between 1-10 kg, a dosage of ¼ ml should be given. For bigger cats that weigh between 10-20 kg, a ½ mL of penicillin dosage is required. Note that the veterinarian will determine the number of antibiotics needed by your cats.

Aside from the dosage, the administration is also one of the concerns of many pet owners. Penicillin for cats is administered by injected the medicine deep into the muscle once every 24 hours. The treatment should continue for another day or two even after the symptoms have subsided.

After the administration of antibiotics, your cat may be a bit irritable due to the mild soreness caused by subcutaneous administration. At this point, you should closely monitor your cat to see any signs of improvement. If there is an absence of progress or recovery, bring her back to the veterinary to be re-evaluated.

Let’s Do A Bit of Recap

Allow me to reiterate that the dosage of penicillin for your beloved cat is highly dependent on her body weight. Never try to double the dosage even if you feel that your cat is suffering from the serious form of bacterial infection. To recap, make sure that you perform the following:

  • Get your cat tested for bacterial infection and let her be checked by the veterinarian
  • Always follow the vet’s prescription (brand, dosage, and administration).
  • If you are not comfortable injecting your own cat, it is best to let the veterinarian perform it.
  • Always check sign of possible allergic reaction to penicillin

We clearly love cats and we will do everything to keep them healthy. However, medicine should always be given with caution. I hope that I was able to answer your question on penicillin and cats. Feel free to write down your questions and concerns, and I would certainly get back to you the soonest.

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Debby Jackson

Hi there, I am Debby. I am your modern-day cat lady who is just utterly crazy about cats. I am always thirsty for new knowledge on how to keep my feline friends happy and healthy all the time.

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