Often external parasites other than fleas, and also intestinal worms, can increase the itch reaction. The reaction that occurs to cause itch is complicated and not well understood. Many times there is an immunologic reaction that causes an accumulation of immunoglobins in the skin and an exudation of serum. This allows growth of skin bacteria which can stimulate further formation of immunoglobins at the site. A great interruption of the morphologic integrity of the skin results.
Antibodies combine with antigen to cause many other reactions as well.
Among them is the accumulation of mast cells and their production of other substances which cause itch. Further morphologic destruction ensues. However, once the immune, morphologic and inflammatory changes occur, these changes, especially those of inflammation, stay in the area for long periods of time. What follows is an outline describing ways to deal with some of the more common problems which cause or intensify itch. As stated above, shedding is a legitimate cause of itch.