Photosensitization/ Photosensitizational Dermatitis

Photosensitization is the allergic reaction of the skin to light due to the presence of photodynamic agents (originated from certain drugs, plants or other substances).

Host:

Ø  Human,

Ø  Cattle,

Ø  Sheep,

Ø  Goat,

Ø  Pig and

Ø  Horse.

Clinical Signs

Ø  Burning or itching sensation,

Ø  Erythema,

Ø  Inflammatory edema,

Ø  The skin may be necrotic and may slough off within few days in severe cases,

Ø  Affected areas of animals are- teat, udder, perineum,

Ø  In sheep, muzzle, head and ears are affected and this head is called ‘Big head’ in South Africa and ‘Facial Eczema’ in New Zealand,

Ø  In horse, face, lower portion of limbs and unpigmented skin are mostly affected,

Ø  Healing or gangrene and death may occur.

Conditions required for Photosensitization

Ø  Direct sunlight,

Ø  Photodynamic substance in circulation and

Ø  Unpigmented area of the body.