Mead acid is an omega-9 fatty acid which was first characterized by James F. Mead. With some other omega-9 polyunsaturated fatty acids, animals can produce Mead acid de novo. Its inflated presence in the blood is an indication of deficiency of essential fatty acid. This acid is found in cartilage in large quantities.
References:
https://en.wikipedia.org/wiki/Mead_acid
http://www.tuscany-diet.net/lipids/list-of-fatty-acids/mead/