• An abscess forms when infection, inflammation, and damaged cells cannot be cleared by the body.
• Abscesses can occur when bacteria are deposited under the skin (as with bite wounds or other wounds).
• Abscesses can cause pain, fever, and lethargy (tiredness) until the infection is cleared up.
• Abscesses are treated with antibiotics and possibly surgery, depending on the size and severity of the infection.
• Keeping cats indoors is a good way to prevent abscesses caused by bite wounds.
• Rabies is passed through bite wounds, and prevention/quarantine should be considered when treating an abscess associated with a bite wound.

What Is an Abscess?
An abscess is a pocket of pus that is formed when the body’s immune system is unable to quickly clear a site of infection. Pus is a liquid collection of inflammatory cells, bacteria, and damaged tissue. Abscesses can form in any part of the body and often result from bacterial infections in bite wounds, tooth roots, and anal glands. Abscesses just under the skin are quite common in indoor/outdoor cats. This article focuses on abscesses that form when a cat is bitten by another cat or a wild animal.

Cats that are allowed outdoors are the most likely to have bite-wound abscesses because these cats have the opportunity to fight other animals. During a fight, the skin can be punctured by a tooth or a claw.  Bacteria on the tooth or claw are deposited under the skin, and the immune system activates to fight off a possible infection and promote healing. Unfortunately, if the body’s initial attempt is unsuccessful, the skin may heal over the wound and trap the bacteria, damaged tissue, and inflammatory cells under it. At this point, there is no easy way for this material to leave the body and a pocket of liquid pus forms.

What Are the Signs of an Abscess?
An abscess usually presents as a painful, fluid-filled lump under the skin. You may see a small scab over a puncture wound near the lump, but sometimes abscesses aren’t even noticed until they break through the skin and pus oozes from the site. Sometimes cats develop a fever before the abscess is obvious and the only change noticed is that their appetite and activity level may have decreased.

How Are Abscesses Diagnosed and Treated?
If you believe your cat has an abscess, it is important to go to your veterinarian as soon as possible.  Once an abscess forms, it is very difficult for the body to remove the material and fight the infection by itself. An untreated abscess can lead to deeper or more widespread infection. Antibiotics are needed to help fight the infection. However, the abscess commonly needs to be drained in order for healing to occur. In some cases, a sample of the fluid may be sent to a diagnostic laboratory to identify the bacteria and the most appropriate antibiotic. If an abscess is allowed to progress, permanent damage could result.

Since it is difficult for the body to clear the buildup of pus, it is often necessary to open an abscess and flush it with solution to allow the pus to drain. If the abscess pocket is large and there is concern that another abscess may form before the antibiotics take effect, your veterinarian may choose to place a surgical drain to promote removal of fluid for a few days. Then, once the antibiotics have controlled the production of pus, the drain can be removed and the wound can heal completely.

One of the biggest concerns with bite wounds is the spread of infectious diseases like feline immunodeficiency virus (FIV, also known as feline AIDS) and rabies. Only cats can get FIV, but the rabies virus is fatal and can be transmitted to people. Even if your cat’s rabies vaccination is up-to-date, state regulations may require your veterinarian to administer a booster vaccine if your cat is bitten. If your cat is overdue for or has not received a rabies vaccination, it is possible that your cat will have to be quarantined for a period of time. Each region has its own regulations regarding rabies exposure and quarantine procedures. Your veterinarian will advise you about the law in your location.

How Can I Prevent Abscesses?
The best way to prevent bite wound abscesses is to keep your cat indoors.  Even though fights sometimes occur among housemates, transmission of infectious diseases like rabies is less likely among a group of vaccinated indoor cats.  If you do choose to allow your cat outdoors, you should be sure to do the following:

• Spay or neuter your cat—this will make your cat less likely to become territorial and get involved in fights.
• Keep your cat’s rabies vaccinations up-to-date—rabies is a deadly virus that can be prevented from  causing disease with regular vaccinations.
• Check your cat frequently for bite wounds, lumps, or other injuries.

A biopsy allows your veterinarian to determine the types of cells in a tissue sample.

• Biopsies are commonly used to determine if growths are cancerous but can also help determine the severity of a disease.
• The tissue removed during a biopsy is examined under a microscope by a veterinary pathologist, a specialist in examining cells and tissue samples.
• Some form of anesthesia is generally required to perform a biopsy.

What Is a Biopsy?
A biopsy is a surgical procedure in which a tissue sample is removed from the body and examined under a microscope. In some cases, only a small sample is removed for analysis. In other cases, several samples may be removed, or an entire growth may be removed and examined.

What Is a Biopsy Used For?
Dogs and cats commonly develop lumps and growths on their skin. Sometimes these lumps are cancerous, but in other cases, they are simply warts or other noncancerous (benign) growths. Examining a lump does not always give your veterinarian enough information to tell whether it is cancerous or not. A biopsy may be recommended to obtain more information about a suspicious lump.

A biopsy can also be used to diagnose a condition or determine the severity of a disease. For example, if an animal has liver disease, a sample of the liver can be removed (during a biopsy) and examined under a microscope to help determine the cause and extent of the liver damage.

How Is a Biopsy Performed?
Some form of anesthesia is generally required to perform a biopsy. Depending on several factors, including where the tissue sample(s) is/are located and how many areas need to be sampled, your veterinarian will decide whether to use local anesthesia, sedation, or general anesthesia. Local anesthesia usually involves injecting a medication in and around an area of the body to make it numb.

If local anesthesia is used, your pet will likely be awake during the biopsy. In contrast, if sedation or general anesthesia is used, the patient is heavily sedated or completely asleep during the procedure. Sometimes, if a growth is on the surface of the skin and is very small, your veterinarian may be able to perform a biopsy using local anesthesia. However, if the area to be biopsied is within the abdomen, for example, or if multiple areas will be biopsied, general anesthesia is usually recommended.

Your veterinarian has a few options when deciding how to perform a biopsy and how much tissue to remove. In an incisional biopsy, a small sample of tissue is removed from a larger mass. In an excisional biopsy, the entire growth is removed and submitted for biopsy.

Once the tissue is removed, your veterinarian will submit it to a diagnostic laboratory. There, a veterinary pathologist (a specialist at examining cells and tissue samples) will examine the tissue under a microscope to make a diagnosis. Results are generally available within several days.  

What Are the Benefits and Risks of a Biopsy?
Biopsies are very important for helping to confirm a diagnosis. With many types of cancers, early diagnosis is helpful for determining the course of treatment and can help increase the chance of survival. Biopsies can also help to confirm causes of other conditions, including skin lesions as well as diseases of the kidneys, liver, or bone marrow.

Your veterinarian will take many precautions to help ensure that your pet is safe during the biopsy and fully recovers afterward. To help reduce the risk of complications associated with surgery or anesthesia, your veterinarian may give your pet a full physical examination and check your pet’s blood work before the biopsy.

Biopsies are very safe, routine procedures. The risks associated with a biopsy depend on several factors, including the overall health of the patient, the location of the area to be biopsied, and how many samples are taken. Be sure to discuss any questions or concerns with your veterinarian.