What are the Uses of Penicillin for Dogs?

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  • Written By: Bethney Foster
  • Edited By: Melissa Wiley
  • Last Modified Date: 16 November 2018
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Penicillin for dogs is most often prescribed as part of treatment for a bacterial infection. It is commonly prescribed for infections of the urinary tract, lungs, and kidneys. A topical penicillin lotion or ointment may be used to treat various skin infections, and penicillin is also sometimes used in treating leptospirosis, wounds, and dental infections.

When prescribing this antibiotic, veterinarians must consider several different factors before determining the dosage to give to the individual dog. He or she will consider how severe the infection is and consider the dog’s size and age. The veterinarian will also try to determine if the dog has any history of or propensity toward an allergic reaction to drugs in the penicillin family. Penicillin may be given as an injection, as an oral liquid or pill, or as a topical ointment or cream.

Owing to several possible serious side effects, veterinarians are prescribing penicillin for dogs with less frequency than they once did. They are more likely to prescribe a different antibiotic if another treatment is available. Possible side effects of penicillin include yeast infections, vomiting, and diarrhea. Dogs are also prone to allergic reactions that can include eczema, swelling, and itching. Even more serious, this antibiotic can sometimes cause kidney damage, liver damage, and a weakened immune system.


Penicillin for dogs can also lead to type I hypersensitivity. This is a severe allergic reaction that can cause anaphylaxis, and the dog may suddenly develop diarrhea, vomiting, and go into shock. Seizures, coma, and even death can quickly follow.

Veterinarians are more likely to prescribe amoxicillin, which is part of the penicillin family, than penicillin for bacterial infections in dogs. While some of the less serious side effects associated with penicillin are possible with amoxicillin, the more serious side effects are uncommon. Other similar drugs in the penicillin family are penicillin G and ticarcillin.

Both penicillin and amoxicillin work to treat infections by impairing production in the bacteria’s cell wall. Drugs in the penicillin family are not effective in treating dogs with viral or parasite infections, though they may be prescribed in some instances to prevent possible secondary bacterial infections from developing. There are also some bacterial infections against which penicillin drugs will be ineffective because the bacteria have developed resistance to the antibiotic.


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Post 11

We woke up the other morning, (3 days ago) to find our dog with a lump in her eye lid filled with puss. We called the vet and was told that they were booked solid until Wednesday. A whole eight days away. But if it was an emergency, we could go to the office and sit and wait to see if there were any no shows and we could have that spot.

Well I was not going to take that chance and sit there all day and not be seen. And I was not going to wait eight days to get her seen. So we made the decision to give her some penicillin. We have had to use it in

the past with a rabbit that I had that had a similar wound.

So I went to Tractor Supply and got a bottle of it and a pack of needles. Going by her weight we gave her 6cc and waited. The next morning her eye was much better. Not fully healed, but better. She could open it and the pocket was almost gone. We gave her another shot with the same 6cc. The following day she could open her eyes completely, and there was no sign of the pocket. But just to be sure we gave her a third shot and there has been no sign of it coming back.

Post 10

I just got back from the vet, and she prescribed something called Clavamox for my dog. I was just looking it up trying to see what it was. She gave it to him, because she thought he might have been too small to handle actual penicillin. It is a pug, and she also said something about some breeds typically having more problems than others handling certain antibiotics.

After I looked it up, apparently Clavamox is just another trade name for amoxicillin. She prescribed it for what she decided was a urinary tract infection. I guess we will see what happens. Hopefully it will clear everything up.

Post 9

@jcraig - My dog had something similar a couple of years ago. It was a green buildup in the corner of one eye. I eventually took her to the vet, and they did say it was a bacteria infection and gave me some droplets to use. I don't remember what the actual name of the stuff was, but it wasn't penicillin or amoxicillin. It just came in a little plastic bottle like regular eye drops would.

It is easy to use as long as you can get your dog to hold still. It worked pretty fast, too. I think the infection was gone after about 4 days, and the whole treatment just took 10, I believe.

I don't remember what the side effects were for the medicine, but I don't think it was anything serious. It was a pretty inexpensive treatment, too. I think it just cost 12 dollars or so for the bottle.

Post 8

Is it possible to have penicillin in a liquid form? My dog has what looks like some kind of infection in his eye. It is basically a lot of green discharge that builds up over the course of the day. I wipe it away a few times a day, but it has been coming back for almost a week now. I have read online, and it says green discharge is an infection.

I happen to be taking him to the vet in a couple of days for his yearly rabies vaccination, so if it hasn't gone away by them, I'll see if they can do something for him. I am just wondering what the typical treatment is for something like this.

Do antibiotics have to go through the bloodstream, or are they just as effective if they are topical treatments or like an eye drop? Has anyone ever experienced anything like this before?

Post 7

@Monika - Good point. The same thing happened to my friend's dog a couple years ago. The dog had gotten some type of skin infection, and so my friend took him to the vet. They decided to give him penicillin or some other similar antibiotic. It worked for a while, but then he forgot to keep giving him the tablets. I guess the dog didn't like taking them, and it was always a hassle, so he gave up.

Eventually, the infection came back and was worse than it was before. Luckily, his dog didn't have any reaction to the drugs, so they increased the dosage or something, and it finally got rid of the infection.

Post 6

I'm always surprised by the amount of human medicines that can be used on animals too! For example, my cat is a diabetic, and he gets insulin from the human pharmacy. It's the exact same stuff that human diabetics use too.

That being said, I just want to remind everyone that antibiotics work the same in dogs as they do in humans. You have to give your dog the entire course of antibiotics, even if they seem to be doing better. If you don't, you risk creating an antibiotic resistant superbug.

Post 5

@starrynight - I think every dog reacts a little bit differently to antibiotics (just like people). My mom had to give her dog penicillin awhile back and her dog didn't have any kind of reaction.

I think you definitely have to watch the penicillin dosage for dogs though. As someone pointed out earlier, the dosage goes by body weight. I might be paranoid, but I would definitely double check to make sure the vet prescribed the right dosage if I had to put my pet on penicillin.

Post 4

My friend had to put her dog on dog antibiotics awhile ago. The vet chose penicillin and the dog experienced some unpleasant side effects. The dog didn't have an allergic reaction or anything, thank goodness, but it was still an unpleasant experience for my friend and the dog.

The poor dog got a lot of gastrointestinal symptoms as side effects. He was vomiting and having diarrhea, so my friend took him back to the vet. They ran some tests, but in the end they decided the symptoms were being caused by penicillin. They switched him to a gentler antibiotic and then he was fine!

Post 3

@ddljohn-- As far as I know, for injections, it's 1ml for dogs weighing up to 20 pounds and for 2ml for dogs weighing 20-40 pounds. 2ml sounds right for a 35 pound dog but some dogs are just more sensitive to medications than others. That's why doctors tend to start with a lower dose of penicillin to see how the dog tolerates. An allergic reaction could be the issue as well, make sure to talk to the vet about your concerns.

When it comes to penicillin antibiotics for my dogs, I've seen that they tolerate the penicillin ointments a lot better than the injections for skin problems. I used a penicillin ointment on one of my dogs recently for

a hot spot- the general term for dermatitis.

It has similar symptoms as mange but it's caused by excess moisture in the fur that forms a bacterial infection in one spot. The dog that got it is a maltese and has long thick fur. We used the penicillin ointment on the hot spot for about a week and it resolved.

Post 2

@turquoise-- My dog has been given penicillin too. He has a staph infection. Do you know what the dose was for the penicillin that was given to your dog? Was it in tablet or injection form? And how much does your dog weight?

I'm curious because my dog was given 2ml of penicillin this morning and he threw up half an hour ago. He weighs 35 pounds. I'm wondering if this penicillin dosage was too much. We're going back for another injection tomorrow and I will surely tell the veterinarian about the vomiting but I don't know if there is something I need to be doing about it now.

Did your dog vomit during the penicillin treatment?

Post 1

I'm personally allergic to penicillin and hesitated a lot when my dog's vet decided to give her penicillin for mange. Mange is a horrible skin infection caused by mites. It makes my dog itch and scratch like crazy and her skin ends up bleeding and balding.

I first asked the vet to use other treatments for it and we did try the weaker penicillin amoxicillin for dogs but it did not work. The itching didn't go away and I could see that my dog was in a lot of pain. The veterinarian convinced me that it was time to giver her penicillin as the infection clearly needed a stronger antibiotic. I agreed and I'm glad I did.


just a couple of doses, my dog felt so much better and itched less and less. After the full treatment, she was all better, the inflammation and bald spots on her skin slowly disappeared.

Penicillin can be a risky medication to use for both humans and pets. But there are times when other treatments just don't work. I'm glad I didn't let my opinion of penicillin prevent my dog's treatment.

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