cat, lesion on fur/skin

Question
my cat a perfectly round lesion on his skin, it is red and does not heal. He is eating fine and behaves the same as before. He does seem like he lost weight though. Can you tell me what this might be?

Answer
Hi Lisa?  It could just be a skin allergy, or if he goes outside, it sounds as though there is a strong possibility it could be ring worm.  Because he is losing weight, I would definately recommend a vet visit for diagnostic procedures.  If it is ring worm, it will definately need to be treated, and this can cause weightloss. Hyperthyroidism can cause weightloss as well.  Blood work would be your best bet in finding out what may be going on with him.
I wish I could be of more help and I hope he is feeling better soon!
Hilary