concerned about spot/sore on my cat

Hi hallo to everyone, great site, I have just noticed and photographed a spot on my cat,

can anyone tell me what it is and what to do about it, thank you in advance for any help

http://i11.photobucket.com/albums/a185/Thon01/IMG_7773.jpg

Michael

Do you have another cat and do they play-fight?

 Hallo Oriental Slave, thank you for your reply, Oh yes, the night before last there was the sound of cats fighting and I went into the garden to find my cat sitting on the fence, and a black and white cat dissappeared off. My cat is female and the black and white cat is male, I think he is a stray, he only has 3 legs, I often find him asleep in the garden or sheltering from the rain. I do give him some food, he is very scared of people, but very aggressive towards other cats, his nose and the top of his head are nearly always displaying fresh scratch marks, I think he may be a little traumatised, but it is the first time that there has been an altercation between him and my cat and generally speaking they seem to tolerate each other without any problems

It looks like a bite mark to me also. Keep it clean with hydrogen peroxide, working it into the puncture, and watch for swelling. It looks clean and small so she's probably fine.
 

If you look very carefully you might find a second bite mark.  Personally since it looks clean and dry I would simply leave it to heal, obviously keeping a close eye on it for any reddening or other symptoms.

Yes she does look fine

thank you Simka and Oriental Slave