An abscess is a localized pocket of pus that forms when the body walls off a bacterial infection or contaminated tissue.
π How an abscess forms; step by step
1) When Bacteria enter the tissue
Usually through a wound, injection site, thorn/puncture wound, bite, or other trauma.
In cattle, injection-site abscesses can occur when injections are given with contaminated equipment, into inappropriate tissue, or when hygiene is poor.
2) The immune system detects the infection.
Bacteria and damaged cells trigger an inflammatory response.
3) Blood vessels dilate and become more permeable, allowing immune cells and fluid to enter the area.
4) Neutrophils arrive
Neutrophils are among the first cells to attack the bacteria.
They engulf and destroy bacteria but many of them also die during the process.
5) Pus accumulates
The mixture of dead neutrophils, bacteria, damaged tissue, inflammatory fluid and cellular debris forms pus.
This creates a soft or fluctuant center.
The body walls it off
6) Fibroblasts and other cells form a layer of granulation tissue and eventually a fibrous capsule around the infection.
This is the bodyβs attempt to prevent the infection from spreading and the abscess matures
6) As pus continues accumulating, the swelling may become warm, painful and fluctuant.
Eventually, it may: rupture externally, releasing pus;that drain through a sinus tract; or remain encapsulated and become chronic.