Medical Corner:
Skin Abscesses in Small Rodents

Jan McArthur, RVT
From the May/June 1999 Rat & Mouse Gazette

An abscess is a localized collection of pus anywhere in the body, surrounded and walled off (closed) by damaged and inflamed tissue. These can be internal and, if they are, then they indicate a much more serious problem brought on by another illness. Most often what is seen in rats and mice are external. Skin abscesses are fairly common among all species of small rodents that are kept as "pocket pets". These can be frightening to the owner and can cause serious illness in the pet. Why does it happen? How serious is it? What can you do to treat or prevent it? Hopefully, I can shed some light on this for all rodent owners.


Species of bacteria are everywhere. We cannot live in a sterile environment; it just isn't possible. When our pets receive an injury that breaks the skin, that break opens the door for bacteria to move in. The injury can be minor, such as a scrape from a rough surface, or it can be a serious injury such as a bite wound from a cage mate.

The bacteria Staphyloccus aureus is the most common bacteria found in an abscess, although there are other bacteria species that may be cultured from an abscess site. S. aureus is the same bacteria commonly found in boils of the human skin. Most people have heard of a "Staph infection." This problem is the same thing. For our pets an abscess is similar to a human boil, but it sometimes is a little more serious for them. S. aureus is also commonly the causative agent of ulcerative pododermatitis, aka "bumblefoot". Those bumbles themselves are a form of abscess. There are many ways this nasty bacteria can cause terrible problems for our pets. Do be aware that it is possible for humans to spread this bacteria to them by not washing our hands before handling them. S. aureus is a normal resident on the skin of humans.


This is difficult to answer; it can be a serious problem if allowed to get out of hand. The bacteria affecting rodents could possibly spread to the entire body creating an ulcerative dermatitis, which could become deadly. It could also enter the blood stream causing the pet to be septic; in other words, the pet could have blood poisoning and that would absolutely be deadly without swift, aggressive treatment by a veterinarian. If treatment is begun at the first sign of an abscess, the chances for recovery are excellent.


It's best to see a veterinarian right away because the vet can lance the abscess. Squeezing it yourself can cause the infection to go inside rather than outside, pushing it deeper into the body instead of forcing it out. If that happens, the bacteria causes a much more serious illness that could possibly kill your pet. Lancing is a minor surgical procedure so that is why it's best to see a vet. A vet may or may not use anesthesia, it often depends on how large the abscess is and where it is located on the pet's body. The lancing is done with a scalpel blade, and then flushed with saline and antiseptics. Stitches may be needed if the abscess is large. Bandages may hinder the progress of healing by sealing off the wound from air so they often are not used. Usually the pet is given oral and/or injectable prescription antibiotics to ensure that a serious infection does not cause complications. If the abscess is very small and superficial, the systemic antibiotics may not be necessary, but usually those will be prescribed anyway as a precaution.


Practicing good sanitation at all times is the best defense against this problem. Removing fecal material in the cage as well as any bits of food that have spilled is an important part of sanitation because those are sources for bacterial growth. Disinfect the rodent home at least once week if not more often, depending on how many animals reside in a given cage. Use soft, absorbent bedding materials that contain no sharp pieces and remove any sharp, abrasive, or rough surfaces that may be in the cage. Cover wire floors with plexiglass or some other sturdy covering. Feed clean food and disinfect the water bottle every 2 to 3 days.

If an accident happens that leaves your rat or mouse with a wound, no matter how minor it may be, flush it with a good antiseptic such as chlorhexidine or peroxide 2 or 3 times a day until it has scabbed over and has begun to heal. If you are vigilant at keeping that wound clean, chances are good that it will heal before it becomes a serious problem that requires a vet. However, please don't hesitate to see the vet if necessary!