Cats that fight with other cats get abscesses rather easily because they have tough skins but very sharp claws and teeth. When a claw or tooth penetrates the skin and pierces right through the skin layer, it acts like a little injection of bacteria between the skin and muscle layer beneath because the tough skin tends to seal around the puncture wound immediately.
image source: Pixabay
The bacteria inside the cat's body then forms a little pocket and begins to multiply. Because there isn't a rich blood supply between the skin layer and the muscle layer, the body doesn't have a good way to fight the bacteria and if you give a cat antibiotics, they can't reach the bacteria either. The bacteria keep multiplying and feeding off body fluids, until a large pocket of extremely smelly pus forms and the skin layer will eventually burst open to release the pus. If the pus all drains out, the abscess will heal but if some remains behind and the skin closes up, it will start forming a new abscess. There is also a danger that bacteria get into the blood stream and lymph nodes and spread around the cat's body, making it very ill. If the cat stops eating and develops a fever, this is probably what has happened and a cat must get antibiotic treatment or it will die.
So when a cat suddenly develops a large lump, usually somewhere around the head, neck or legs it probably has an abscess and it is best to take it to the vet, especially if it is not eating. The vet will assess the lump and decide when or whether it should be drained or not. Sometimes, you won't notice that a cat has an abscess if it forms in an area where there is a lot of loose skin, but suddenly a large hole in the cats skin appears and you can see right through to the muscle layer beneath. If the abscess has burst very recently, you may see some blood, but these large rips in the skin don't bleed much, leaving many cat owners puzzled about what just happened to the cat and they rush off to the vet expecting the vet to stitch up the wound. Generally, the wound might be shaved to remove the hairs immediately around the hole but it will not be stitched closed because the abscess needs to drain fully. If the cat has a fever, they should be put on antibiotics but often, an abscess can burst by itself, the cat will lick and clean it by itself and it will heal slowly without any intervention. If the hole in the skin is large, the wound may take up to six weeks to fully close and this is not a problem, although it can look quite scary to the cat's owner, because the layers underneath are fully visible. It's actually more of a problem if the abscess only makes a tiny hole when it bursts, as this is more likely to close up before the abscess is fully drained and then it will reform. This also tends to happen if an abscess is in an area which a cat can't reach to lick, such as on the face. Then the owner needs to help by cleaning the wound a couple of times a day with plain water because an abscess generally needs about 48 hours to drain fully and the wound needs to stay open for this to happen. Antiseptics or hydrogen peroxide should not be used because this will damage healing tissue. Even antibacterial ointment is not necessary, the skin will heal on their own
When I was living at my previous address, my cats were always fighting with the neighbour's cats and I got quite used to treating them and I was lucky that a few of them could be treated at home and didn't need to go to the vet to be drained, which can get very expensive.
Next, I will explain what happens if an abscess needs to be drained
