Why is the scratch from a cat swollen? - briefly
A cat scratch can become swollen due to bacteria, such as Bartonella henselae, entering the wound, leading to inflammation or infection. Allergic reactions or the body’s immune response to foreign substances can also cause swelling.
Why is the scratch from a cat swollen? - in detail
A scratch from a cat can become swollen due to several factors, primarily related to the body's immune response and potential bacterial contamination. Cats have sharp claws that can introduce bacteria deep into the skin, even from a minor scratch. One of the most common bacteria associated with cat scratches is Bartonella henselae, which causes cat scratch disease (CSD). When bacteria enter the skin, the immune system reacts by sending white blood cells and other immune mediators to the affected area, leading to inflammation, redness, and swelling. Additionally, cat claws may carry other bacteria, such as Pasteurella multocida or Staphylococcus aureus, which can cause localized infections. The body's inflammatory response is a protective mechanism to isolate and eliminate the invading pathogens, but it can also result in discomfort and visible swelling. In some cases, an allergic reaction to proteins or substances present in the cat's claws or saliva can exacerbate the swelling. If the scratch is not cleaned properly, bacteria can multiply, leading to more severe inflammation or even pus formation. It is essential to clean the wound thoroughly with soap and water, apply an antiseptic, and monitor for signs of infection, such as increasing redness, warmth, or fever. If the swelling persists or worsens, medical attention may be necessary to rule out a bacterial infection or other complications.