− | The history and clinical signs are important in order to differentiate whether the condition is primary or secondary. In the case of primary photosensitisation there is often a history of exposure to plants containing photodynamic agents such as St. John's Wort or clover. Alternatively, there may be a history of administration of drugs such as phenothiazines, sulphonamides or tetracyclines. | + | The history and clinical signs are important in order to differentiate whether the condition is primary or secondary. In the case of primary photosensitisation there is often a history of exposure to plants containing photodynamic agents such as St. John's Wort or clover. Alternatively, there may be a history of administration of drugs such as phenothiazines, sulphonamides or tetracyclines. Signs of liver disease are usually absent. |
− | | + | In animals affected by secondary photosensitisation, the classic skin lesions are accompanied by signs of liver disease. Serum biochemistry often reveals increased liver enzymes (ALP, GGT, SDH and ALT). |