Abscesses are one of the more common problems that is encountered in our bunny patients.
They are often caused by Pasteurella multocida, however a large number of other bacteria including Staphylococcus
and Pseudomonas have also been isolated and cultured.
Mixed infections are also common. Unlike abscesses in cats and dogs, rabbit abscesses contain very thick pus and thus drain poorly.

Why do abscesses form?

An abscess can form anywhere that the skin is broken or punctured, allowing bacteria to enter the deeper layers of skin and proliferate. It takes about 7-10 days from the time the bacteria enters the body until pus is formed. Lumps can appear and seem to grow rapidly in size overnight. Abscesses of the head are often a result of dental problems. If the teeth are involved, the rabbit commonly will experience difficulties in eating and become anorexic. A diagnosis of an abscess is made by placing a large bore needle into the mass and aspirating its contents. The material can then be examined under a microscope. Often multiple abscesses are present.

How are abscesses treated?

The method of treating the abscess depends on it’s size and location. The contents of the abscess should be cultured in order to determine which antibiotic will be most effective. Thick-walled abscesses can be surgically removed in their entirety; others are lanced and their walls curetted, resulting in a large opening left to scar in naturally.


Detailed articles on treatment options:

AIPMMA Bead Treatment: Management of Abscesses of the Head in Rabbits. Written by R. Avery Bennett, DVM, MS, Diplomate ACVS

Bicillin treatment: Successful Eradication of Severe Abscesses in Rabbits with Long- Term Administration of Penicillin G Benzathine/Penicillin G Procaine.
Written by Marcy E. Rosenfield (Moore).

Links to related articles:
Abscesses in Rabbits: Written by Jaqueline Warner, DVM.(HRS article)


Those who have experience dealing with rabbit abscesses know how difficult abscesses are to cure. In addition to the fact that the pus found in rabbit abscesses is thick and does not drain easily when the abscess is opened, rabbit abscesses often develop finger-like projections that protrude into the surrounding tissue. These ‘fingers’ often form new abscesses if they are not removed or properly cleaned.

Sometimes, current abscess treatment methods are successful -other times they are not. Keeping in mind that treatment efficacy depends upon the bacteria present and culture and sensitivity results, one option that is promising in the treatment of abscesses is the administration of injectible penicillin. It should be noted that penicillin should NEVER be given orally to rabbits, but when given as an injection, it is generally well tolerated.


A Vet’s Notes:

Definition, Causes and Risks

Abscesses (a localized collection of pus in any part of the body that is the result of an infection) occur when an area of tissue becomes infected and the body is able to ‘wall off’ the infection and keep it from spreading. White blood cells, the body’s defense against some types of infection, migrate through the walls of the blood vessels into the

area of the infection and collect within the damaged tissue. During this process ‘pus’, an accumulation of fluid, living and dead white blood cells, necrotic (dead) tissue, and bacteria or other foreign materials, forms.

Abscesses can form in almost every part of the body and may be caused by bacteria, parasites, or other foreign materials. Abscesses in or just below the skin are readily visible, because they are raised and painful. Abscesses in other areas of the body may not be obvious, and may cause significant damage if they involve vital organs.

Significance to Rabbits

Whereas dog and cat abscesses tend to develop quickly, and burst through the skin in a flow of thin liquid, bunny abscesses are quite different. Slow to develop, bunny pus is quite thick with the consistency of toothpaste. Given the furry nature of our bunny friends, and how sensitive they are about being touched in certain areas, abscesses often can go undetected until they are embarrassingly large.


While most abscesses are simply lanced and allowed to drain naturally, bunny abscesses present a particularly challenging problem to the veterinarian:

• Rabbit skin is very thick and durable. In addition, the abscess wall created by the rabbit’s immune system is so thick that the abscess can become large without rupturing.

• If simply lanced like other mammalian abscesses, rabbit pus does not drain by gravity, or extrude well with pressure. Instead, the slit sits open and the surface of the pus dries to form a sealing crust.

• Abscesses are difficult to culture – pus contains mostly dead bacteria, so surgery is needed to sample the inner wall of the abscess to harvest a sample of the initiating bacteria.

• When an appropriate antibiotic is determined, the thick wall of the abscess usually prevents the antibiotic from easily reaching the enemy, so the abscess might grow even when using the appropriate antibiotic.

• Abscesses grow from infections, such as from the root of a bad molar, or from a bug like Pasteurella sp, which may not ever be completely eliminated from the rabbit’s body.

Current Treatment Strategies

Always attempt to culture the offending bacteria when possible. If surgery is chosen, always try to completely remove the entire ‘capsule’ of pus, thereby leaving behind no

bacteria that may form new abscesses. After surgery, consider depositing antibiotic impregnated methyl methacrylate beads deep in the tissue before closing the skin or administering a long-term (1-3 month) once daily course of an injectible Procaine

Penicillin G, rather than oral antibiotics. Bicillin may be used, if the proper formulation is available and the owner is more comfortable giving injections every other day, rather than daily.

NOTE: Using injectible penicillin has been reported to cause the abscess to dissolve completely even without surgery! Speak to your vet about the safety and availability of
these products.

Dr Markus Luckwaldt, DVM
Amherst Veterinary Hospital,

Button’s Story:

At six years old, Buttons is full of life. A year ago, however, he struggled with facial abscesses. Fortunately, with some perseverance, we are happy to report that Buttons is doing well – and enjoying life as much as ever.

One day in June 2001, Buttons jumped to the floor while I was holding him and broke a tooth. Soon after this incident I noticed that he developed a lump under his chin. The vet said that the lump was an abscess, and that it should be removed. On June 20, I took him in for surgery. Ideally, when surgically removing an abscess, the abscess capsule should be removed intact to prevent the bacteria from spreading. Unfortunately, the abscess burst when the vet put the mask for the anesthetic over his face. Even so, the vet was still optimistic that the abscess wouldn’t return. During the surgery, the vet took a culture of the abscess to try to determine what bacteria was present.

While waiting for the lab results, Buttons was started on oral Baytril. The lab results, however, were inconclusive, and due to the nature of Buttons’ abscess, he was switched from Baytril to Metronidizole. The meds didn’t work: by July 9 another abscess had formed and quickly grew from the size of a pea to the size of a golf ball. The entire right side of Buttons’ face was swollen. I was very disappointed. I was worried about the risk of another surgery at Buttons age and the possibility of tooth root or jaw infection. I wanted another rabbit owner’s opinion, so I talked at length with Carrie (an OREO member) who encouraged me to read information on bicillin (1) and discuss it with my vet.

Although bicillin was not being used routinely in Ontario to treat abscesses, some U.S. rabbit owners had reported having great success with its use, especially with facial/jaw abscesses. I researched this, and other abscess treatments, and went back to my vet. One option we discussed was another surgery and the placement of antibiotic beads at the abscess site. Semi-retired, I was concerned with the expense of this type of surgery and possibility of another abscess. I really wanted to try bicillin – the less costly and less invasive treatment option – first. My vet had not heard of using bicillin to treat abscesses, and was skeptical, but agreed to try it.

On July 11, I got the bicillin (the Canadian manufacturer calls it Duplocillin) and the vet showed me how to give an injection. I didn’t like giving injections, but I did get the hang of it and had no problems giving Buttons his medicine every other day. The Duplocillin made Buttons’ tummy upset, but thankfully Pam (another OREO member) was kind enough give me a tube of Benebac (a probiotic), which helped a great deal.

On July 25, I returned to the clinic. The abscess on Buttons’ cheek was so large, that I was worried that the bicillin was not going to be able to shrink it quickly enough for him to continue eating. In addition, the abscess on his chin returned, so I opted for another surgery. I was very shocked to see the big hole in his face after the operation.

This hole had to be left open, so that I could clean it. The vet told me that the surgery went well and that he hoped he got the whole abscess capsule. He also told me that the abscess on his chin was actually a lymph gland that had filled up with the abscess material. (Apparently, this is what lymph glands do, to get rid of the poison in the body). I was shown how to clean the surgical site with peroxide, which had to be done many times a day. After the surgery Buttons was given Novotrimel (a sulfa drug). As well, I was told that I could keep giving him the Duplocillin, if I wanted, so I continued with the injections. Two cultures were taken during the operation, but again the labs tests came back inconclusive, so we still didn’t know what bacteria had caused the abscesses.

I cleaned Buttons’ wound as often as five times a day with the peroxide (2). As the days went by, the hole started to fill in and eventually it closed up. It healed from the inside out. The lymph gland kept getting bigger and bigger, but then started to shrink and eventually disappeared. I believe it was the Duplocillin that finally caused the abscess to disappear. I continued with the Duplocillin for a monthor so, even after the abscesses were gone and Buttons face had healed. I didn’t want to take any chances that he would get another abscess. I’m thrilled to report that his abscesses never returned.


Roo’s Story:

I had my first encounter with abscesses when Roo was three months old. He suddenly developed a lump on his side, right over his ribs. An x-ray showed that there was a ‘mass’ growing there, but we could not be sure without doing exploratory surgery. I decided to wait and see what happened. At the time, I was an uneducated bunny mom and figured that it was nothing serious and would probably disappear as mysteriously as it had appeared.

Over the next few weeks the lump grew and grew. Roo stopped ripping around the house and he could not lie down comfortably. One day I came home from work to find that the lump had almost doubled in size and he had pulled all the hair off it. I rushed him to the vet and was told that he had an abscess. He went back in the next day for surgery. The surgery was successful and my vet was confident that he had removed all of the abscess. I was so happy. However, Roo was not: he went into stasis after the surgery and had to spend the week at the vet’s.

Finally the day came when he was ready to come home. Even though I had visited him at the vet’s, I almost started crying when I picked him up. His entire right side was shaved and he had an incision that went from his shoulder right down to his hip. I was feeling pretty guilty. If I had just done what the vet said in the first place we could have caught this before it had gotten that big.

I started to think about how Roo developed this abscess in the first place. I read somewhere that abscesses can be caused by animal bites. When I first got Roo he lived with my guinea pig. Of course, back then I had never heard of bonding and put them together in the same cage – I figured that they would be fine together. My guinea pig had lived with my other bunny and they were the best of friends. I was wrong: Roo and my guinea pig hated each other and got into a few fights before I separated them. I am sure now that his abscess was caused by a bite from the guinea pig because it was shortly after I separated them that I first noticed the lump on his side.

During the next few weeks, the incision healed nicely and Roo went back to being his old self. Then, about six weeks after his surgery, I was brushing him and noticed that there was another lump there. I did not know if it was another abscess or something else caused by the surgery. Instead of waiting this time, I quickly made an appointment with the vet. In the two days that I had to wait for the appointment the lump doubled in size. I was sure I was going to get told exactly what I did not want to hear: Roo had another abscess.

I was right. Another abscess had grown exactly where the first one had been. This time, however, Roo couldn’t have surgery. There wasn’t enough skin left there to do another one and close it properly. We put him on Baytril to try to shrink the abscess and give me some time to decide what to do.

It was then that I decided that I was a very uneducated bunny mom. Sure, I knew more than the average person about buns, but not as much as I should. Over the next few days I read everything I could on abscesses and spoke to many people who have had similar experiences. I found that there were many different treatments for abscesses, some very aggressive and some not. Surgery was not an option, so I decided to try bicillin injections.

I printed out everything I could find about bicillin and went to visit my vet. My vet had heard of bicillin, but had not used it. He also did not have the proper supplies in stock. He told me that I could make an appointment with another vet who had experience with bicillin, if I wanted. So, I took a day off work, and in a horrendous snow storm, Roo and I trekked off to see the new vet. Once there, we discussed all the different options for treating the abscess and decided that injections were the way to go. This vet clinic did not have the proper bicillin formulation in stock either, but since I felt that I would be comfortable giving daily injections (rather than every other day), we decided to treat Roo with injectible Penicillin G Procaine rather than bicillin (1).

The next day, I gave Roo his first injection (he immediately decided he hated that!). I must admit that the first couple of injections were tricky, but after about a week I became an old pro. Roo was extremely good about it (surprising, because he has such an attitude!) and never moved, flinched or even tried to run away. During the first week of his injections, a scab developed over the abscess and eventually fell off. Roo now had a gaping hole in his side that was filled with pus. It was not a pretty site to look at and I think that Roo knew it grossed out his grandma because he loved to snuggle up to her with his side pressed against her. I had to clean the abscess several times a day with peroxide and gradually it started to shrink.

Twenty-five days after the first injection I took him back to the vet for a follow-up appointment, and I was smiling all the way there. His side was completely healed. He had gone back to being his old self again, tearing apart anything he could find and giving me attitude! I might have had a big smile going into the vet’s, but I had a huge smile coming out. Roo was cured! No more injections! I was so happy. I was prepared for months of injections, but it only required three weeks. This was nothing short of a miracle. We were just sorry that we hadn’t taken “before” and “after” pictures of Roo.

It has now been almost two months since his last injection and all is still fine. I check his side every day for any signs of something growing. There were times when I was sure that he wouldn’t live to see his first birthday. He has been through so much and has been such a brave little guy.

Roo and I would like to send our thanks to Dr. Korosi and Dr. Luckwaldt for all they have done for us. We would also like to thank all the OREO members for all of their advice and support over the last few months. Roo sends you all lots of kisses!

Footnotes to the article:

(1) Penicillin-G Procaine is given every day. Bicillin, which is given every other day, contains two kinds of Penicillin: Penicillin-G Procaine and Penicillin-G Benzathine. Both kinds of penicillin break down into Penicillin-G. Pen-G Procaine is absorbed into the bloodstream very quickly, but is also excreted quickly. Pen-G Benzathine, on the other hand, is absorbed more slowly, but also maintains a more prolonged level of Pen-G in the bloodstream.

(2) Although peroxide has been argued to be damaging to healthy tissue, it turns the pus into a liquid that can be easily suctioned from the wound.

Successful Eradication of Severe Abscesses in Rabbits with Long-Term Administration of Penicillin B Benzathine/Penicillin G Procaine by Marcy E Rosenfield (Moore).


Read More:

The complete bicillin protocol can be found at:
Successful Eradication of Severe Abscesses in Rabbits with Long-Term Administration of Penicillin G Benzathine/Penicillin G Procaine -by Marcy E. Rosenfield (Moore)

Case studies:
 Bicillin Case Studies