Enzyme immunohistochemical staining of formalin-fixed tissues for diagnosis in veterinary pathology.

Disease diagnosis often relies on the detection of specific antigens in tissue specimens. Enzyme-based immunohistochemical stains of formalin-fixed, paraffin-embedded tissues may be used to identify antigens associated with viral, bacterial and protozoal microorganisms, autoimmunity, and neoplasia. The detection of antigens in routinely fixed tissues offers several advantages over other diagnostic techniques. Sample submission is convenient and facilitates safe handling of potential human pathogens. Retrospective studies of stored specimens are possible. The technique is relatively rapid and enables detection of nonviable microorganisms. In addition, the ability to detect antigens in fixed specimens allows simultaneous visualization of the antigen and the histological lesion which may enhance the accuracy of diagnosis.