Changes

==Clinical signs==

==Clinical signs==

The condition is characterised by clearly demarcated 'sunburn-like' lesions that are confined to unpigmented or hairless areas of the skin. The nose, lips, ears, muzzle and udder are commonly affected areas. In the acute stages, the affected area(s) becomes erythematous and oedematous with exudation and crust formation. Animals may be pruritic or painful.  

The condition is characterised by clearly demarcated 'sunburn-like' lesions that are confined to unpigmented or hairless areas of the skin. The nose, lips, ears, muzzle and udder are commonly affected areas. In the acute stages, the affected area(s) becomes erythematous and oedematous with exudation and crust formation. Animals may be pruritic or painful. other clinical signs may include swollen lips or muzzle, tachypnoea, tachycardia, diarrhoea and salivation.

 

If the photosensitisation is secondary (hepatogenous), icterus may be present. Other signs may include those consistent with hepatic encephalopathy such as head-pressing, circling, and behavioural changes.

If the photosensitisation is secondary (hepatogenous), icterus may be present. Other signs may include those consistent with hepatic encephalopathy such as head-pressing, circling, and behavioural changes.

==Diagnosis==

==Diagnosis==

The classical lesions of photosensitisation are usually sufficient for diagnosis of primary disease. There is often a history of exposure or ingestion of plants such as St. John's Wort or clover or

The classical lesions of photosensitisation are usually sufficient for diagnosis of primary disease. There is often a history of exposure or ingestion of plants containing photodynamic agents such as St. John's Wort or clover. Additionally, phenothiazines, sulphonamides, tetracyclines and mycotoxins such as blue-green algae have been implicated in photosensitisation.