Disclosed is a method for identifying transmissible spongiform encephalopathy in livestock via an electroretinogram, the method comprises producing a biphasic electroretinogram waveform having an a-wave and b-wave from livestock retina in response to photic stimulus, measuring the amplitude of the b-wave, wherein the amplitude is measured from the trough of the a-wave to the peak of the b-wave, measuring the implicit time of the b-wave, wherein the implicit time is measured from onset of photic stimulus to b-wave peak; and comparing said produced waveform to a comparative waveform of livestock known not to have transmissible spongiform encephalopathy, wherein the produced waveform having a decrease b-wave amplitude and increased b-wave implicit time being indicative of livestock having transmissible spongiform encephalopathy.