virus infection involves panvasculitis and consequently increased vascular permeability of small arteries and capillaries. Affected horses show pyrexia, cough, palpebral ooedema, conjunctival ooedema, epiphora and conjunctivits and occasionally blood stained tears. Prominent ooedema of limbs is also a charectristic sign of this disease. Genitalia of the affected horses are often ooedematous. Infected stallions may act as carrier for a long time and a permanent source of infection. The less common signs