Abscess in Pet Rats – Causes & Treatments

If you’ve never had a pet rat before, now’s the time to learn that they are prone to abscesses. This doesn’t mean all rats will get them, but most will. These abscesses can be benign or malign (cancerous) and will vary in size and symptomatology.

Most importantly, early discovery and proper treatment are necessary to eliminate the abscess before it takes off which can potentially save your rat’s life.

So, let’s talk about all this!

What is Abscess in Rats?

Abscesses are pretty much puss-containing lumps forming under the skin. This is an as easy of a definition as you can get. Things become complicated when looking to determine the abscess’s causes and nature. This can make the difference between life and death for your rat because cancer is always a looming possibility.

Symptoms of Abscess in Rats

You will most likely detect the abscess by hand when handling your rat. Smaller abscesses may not be visible with the naked eye, but they are palpable, and you should never ignore them. They are usually solid at the touch, and you can feel them bulging under the skin.

Depending on the abscess’s nature, you have several symptoms to look for:

  • Fast growth – A concerning abscess is one that grows fast under the skin, typically over the course of 1-3 days. If you observe that your rat has a lump under its skin, keep track of its size and shape.
  • Visible puss head – Puss-filled abscesses will showcase a yellow or white tip and may be pointier in late developmental phases. Fresh abscesses will most likely be rounder and with red heads.
  • Signs of injury – Many abscesses are the result of rough rat play or accidental injuries due to rough contact with various environmental decorations. Always check the abscess’s area for any sign of injury. This will immediately inform you of its nature. If you have a skin injury in the abscess’s proximity, or the abscess has formed directly beneath the injury, the abscess may be bacterial. In this case, your rat requires antibiotic treatment to contain the condition.
  • Systemic involvement – In layman’s terms, this refers to a deep-layered abscess that’s causing generalized symptoms, instead of localized ones. So, your rat may exhibit weight loss due to poor or lack of appetite, lethargy, and even organ malfunctioning. The latter will also cause a multitude of symptoms, depending on what organs are affected.
  • Moving growths – If your rat exhibits soft and round tumors (sometimes flat) under the belly that can be moved, consider the possibility that they may be cancerous. This is due to female rats being prone to mammary adenocarcinomas, which are malignant and aggressive tumors capable of delivering a swift death. If your rat has cancer, it will exhibit signs of depression, lack of appetite, and signs of stress, depending on the cancer’s progression.

As you can see, this is a complex topic with plenty of food for thought.

Causes of Abscess in Rats

There are multiple causes for abscess in rats, including:

  • Physical injuries – These are often the result of the rat’s unfortunate interactions with sharp objects located in its habitat. Rats fighting or playing with each other may also experience mild skin injuries that can get infected, leading to abscesses or even generalized infections.
  • Chewing activity – Rats are avid eaters, but this is not the only reason why they chew stuff. Their massive and ever-growing incisors take that spot. Rat incisors never stop growing, so rats need to grind them constantly. Otherwise, they will soon become unable to eat as the teeth grow out of their mouths. So, your rat will perform a lot of chewing, and nothing around them is spared of the destruction to come. This means your rat may chew on hard, sharp, or fibrous materials that could cause cuts in the soft tissue around or inside the mouth. These open wounds are perfect entry points for various bacterial organisms responsible for abscesses and even life-threatening infections.
  • The body’s reaction to invading pathogens – Your rats may become infected with a variety of microorganisms like viruses, bacteria, or fungi. The entry points differ, but they’re most likely micro skin tears, especially around the skin, due to bites or scratches. The pathogens will trigger an immune reaction, as the body produces excess cells and secretions designed to isolate and eliminate the intruders. The protective agents will agglomerate near the pathogen’s entry point and create a mix of dead white and blood cells, which you may know as puss.

The real problem here is that even mild infections can become fatal fast. This is due to how abscesses function. Abscesses located under the skin can swell up and burst, releasing some of the content into the blood stream, depending on their localization. This is what you call a septicemia which is deadly.

So, you should always look into the matter more seriously and treat even mild abscesses with proper seriousness.

How to Treat Abscess in Pet Rats?

Abscess treatment in rats is a sensitive and rather complex topic. You pretty much have several lines of attack, depending on the abscess’s localization, appearance, and causes:

  • Heat treatment – This is good for small and mild abscesses when your rat doesn’t show any signs of generalized infection. This means that the abscess is most likely benign, resulting from typical bacterial infection. Apply a wet and heated material on the abscess itself. Aim for temperatures around 105-110 F and maintain the contact for 10-20 seconds. Doing so attracts more leukocytes (white blood cells) to the affected area, allowing the body to fight off the infection faster. Don’t keep the heat on the area for too long, as this will cause vasoconstriction and restrict the blood flow in the region.
  • Drain the puss – This is necessary in case of larger abscesses with a visible white head. This means that the puss has accumulated in that area, and you need to drain it to allow the wound to heal. You can use a syringe needle to puncture the abscess and drain it gently. Then you need to clean and sterilize the area twice a day with a 0.9% saline solution, a 1:5 betadine solution, or a 1% chlorhexidine solution. It’s best to ask your vet before committing to any type of treatment.
  • Larger incisions – These may be necessary in the case of large or deep abscesses, so I recommend having a professional deal with it instead. This is that much more important, knowing that larger abscesses are difficult to identify in terms of figuring out their nature.

I recommend only treating smaller abscesses that are visibly benign with puss discharges. These are relatively easy to combat. The larger and more complex ones require professional intervention and supervision, as the treatment is often more demanding and requires more precision.

For instance, you can’t apply an antibiotic ointment, in many cases, as the solution will force the abscess to heal from the outside first. This will close the wound but trap the bacteria in, which can lead to internal infections and septicemia.

Rat Abscess Surgery Cost

Expect to pay around $75-$500+, depending on the abscess’s size, localization, nature, and the care provider. The more expensive interventions are reserved for tumor extractions, but smaller, benign abscesses should be cheaper.

Is Rat Abscess Contagious?

Mostly no, but some are. Bacterial abscesses can become contagious if the abscess itself has contact with another rat’s open skin wound. So, it’s safe to say that the infection risk is quite small, given the precise set of circumstances necessary for that to happen.

Malign abscesses are, fortunately, not contagious. Imagine a contagious form of cancer that spreads via skin contact. Am I right, Tasmanian devil?


Pet rats will experience a variety of abscesses and lumps over the course of their lives. Female rats are also predisposed to mammary gland cancer, so they require even closer supervision and assistance.

Check your pet rat regularly, especially as it grows older, and its immune system becomes less effective. Most importantly, always speak to your vet for proper diagnosis and treatment planning.

avatar Jane
Jane is an experienced animal care specialist with a focus on rodents and small mammals, with over 10 years of experience in the pet industry. Her articles provide practical guidance on choosing the right pet and managing common health issues. Jane is an advocate for animal welfare and supports organizations dedicated to protecting wildlife. read more...

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