At a glance
What is an abscess?
An abscess is a pocket of pus under the skin which occurs when bacteria, which reside on the skin or teeth, enter the body via a puncture wound, most often by a bite during a cat fight.
An inflammatory response occurs, drawing huge amounts of white blood cells to the area and increasing regional blood flow. Pus forms, which is an accumulation of fluid, toxins, living and dead white blood cells, dead tissue and bacteria. A thin membrane (pyogenic membrane) surrounds the abscess. This area begins to grow, creating tension under the skin and further inflammation of the surrounding tissues. As the abscess grows, the skin thins and weakens, eventually causing the abscess to rupture, and the pus drains out.
An abscess can form in any part of the body including under the skin, in the mouth (dental abscess) and in organs such as the liver and pancreas. This article relates to abscesses under the skin. The most common bacteria involved are Pasteurella multocida, Streptococci spp., and Staphylococcus spp.
How does an abscess occur?
The most common cause of a penetrating puncture leading to an abscess is from a cat bite. The oral cavity, including the teeth, harbour a high number of bacteria that are injected into the skin during penetration. As the skin is remarkable in its ability to heal quickly, the overlying skin quickly heals from the puncture wound, trapping the bacteria underneath the skin in a warm, moist environment.
Abscesses are most common in un-neutered male cats who are allowed to free roam as they are more territorial and therefore become involved in cat fights with local cats. There is an increase in cats presenting with abscesses in spring as this is cat mating season.
Other causes of abscesses include scratches and any penetrating object such as a thorn, splinter, grass seed or glass shard.
Abscesses occur most often around the head, neck, limbs and back and base of the tail. Not all cats will display signs.
By the time you find the abscess, the skin may be sufficiently thin, resulting in the abscess draining (this is known as pointing and usually occurs when the abscess is close to the surface). If it has drained, you may notice a thick, yellow and foul-smelling discharge and a hole in the skin (see image). If the abscess is deep under the skin, you may notice an indentation (or a ‘pit‘) when pressure is applied to the area of swelling.
Other common symptoms of an abscess can include:
- Hot, swollen and painful area
- Hair loss
- Loss of appetite
- Hunched over appearance
- If the abscess bursts, you may notice oozing and a foul-smelling odour from the affected area
An abscess isn’t always visible, especially as the coat may hide the wound. If your cat is acting off colour, appears to be in pain or displays any other symptoms above, see your veterinarian.
Image monkeymark, Flickr
A physical examination will identify most abscesses.
Your veterinarian may take a sample of the discharge and perform a culture and sensitivity to determine the bacteria involved so that he can prescribe the best antibiotic for that particular bacteria.
Image courtesy Duncan Creamer, Flickr
The goal of treatment is to lance, clean, and debride the area to promote healing.
The fur around the abscess is clipped and cleaned, the abscess is lanced and the pus drained, any dead tissue will be removed (debrided), and the area is flushed with sterile saline to remove any residual pus.
This procedure will be under heavy sedation or general anaesthetic. The cat may need to stay in hospital for a day or two while he recovers.
Treatment is much the same as above, minus lancing. The area is clipped and cleaned; the wound is flushed with sterile saline any dead tissue is removed.
If the abscess is large, your veterinarian will insert a surgical drain to assist with the removal of pus — flush daily with antiseptic or sterile saline as advised.
A long-acting antibiotic injection or oral antibiotics will be given.
- After surgery, your cat will be discharged with antibiotics, and possibly anti-inflammatories and pain relief, administer medication as prescribed.
- It may be necessary for your cat to wear an Elizabethan collar, especially if a drain has been inserted to prevent the drain from being pulled out.
- A warm compress applied several times a day can increase blood flow to the area and speed healing.
- Keep your cat indoors while he heals.
- Watch for signs of infection, including redness, oozing, and swelling of the affected area.
- A follow up will be necessary 2-3 days after surgery to remove the drain and check the area is healing well.
The best way to avoid abscesses in cats is to spay and neuter cats and prevent them from free-roaming.
Check your cat for bites, scratches, and wounds if he has been involved in a cat fight, clean any wounds with an antiseptic (see here for a list of antiseptics safe to use on cats).
See your veterinarian if you notice any lumps, signs of pain or fever. Do not treat an abscess at home as it can rupture into the bloodstream, causing septicemia (bacteria in the blood), which can be fatal.
People can develop abscesses too, especially those in high-risk jobs such as veterinary staff and shelter workers. If a cat does bite or scratch you, clean the wound and keep watch for signs of an abscess or infection. If you do think you have one, seek medical attention immediately.