Bovine spongiform encephalopathy  (BSE), is commonly known as mad-cow disease. It is a progressive neurological disorder of cattle that results from an infection by  an unconventional transmissible  agent.  BSE  is  one of a  group of diseases that affect a number of different mammals. These diseases, known as Transmissible Spongiform Encephalopathies (TSEs), or Prion  Diseases,  result from  the build-up of abnormal prion proteins  in  the brain and nervous system. BSE  attacks the brain and central nervous  system of the animal and eventually causes death.

 Research has shown that TSEs have two characteristics in common: they can be transmitted between animals, and they cause the same spongy decay of brain tissues. A commonly occurring prion disease is  scrapie.  The  symptoms commonly associated with it  are  disorientation, clumsiness and occasionally, aggressive behavior towards other animals and humans.

What caused the disease? Most  experts agree  that the BSE was  spread  by  cattle eating feed that contained meat-and-bone meal (MBM), which contained BSE infected parts of other grazing animals. MBM is produced in a process called rendering,  this is where  otherwise  unused meat  products  are  taken from the animal carcass and turned  into cattle feed.  Cattle can contract BSE if they are fed infected brain tissue. Thus, it is presumed that BSE was  transmitted  to  cattle through  their animal feed.