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Cutaneous sun damage and skin protection: a focus on FiltaClear

Abstract
Phototoxicity (sunburn) and photosensitivity are the two most important forms of sunlight induced disease recognised by veterinary surgeons in the dog, cat and horse. Phototoxicity is mediated by UVB radiation and has a spectrum of presentations, ranging from sunburn to more severe actinic damage and squamous cell carcinoma. Phototoxicity is usually seen on white or non-pigmented skin, especially where there is little hair covering, and is recognised in all three species. Photosensitisation is most commonly seen in the horse and represents an abnormal reaction of the skin to light, caused by photodynamic agents in or on the skin. Sun avoidance and sun protection are important in all of the domestic species, to prevent sunlight induced disease.
Most of the domestic species have a dense haircoat that protects them from excessive exposure to sunlight. However, in areas of the body not naturally covered in hair, or where hair is lost for other reasons, the exposed skin becomes susceptible to damage from sunlight (Miller et al, 2013). In the dog, cat and horse phototoxicity and photosensitivity are the two forms of sunlight induced disease that are of primary concerned to the veterinary clinician (Miller et al, 2013). Both forms of damage are caused by light in the ultraviolet (UV) spectrum. UV light can be divided into UVA, UVB and UVC light.
Phototoxicity is the classic sunburn reaction and is dose dependent. Both UVC and UVB are phototoxic. Fortunately the earth's ozone layer protects us from the most damaging UVC (<290 nm). However, UVB (290–320 nm) does reach the earth's surface and is the wavelength most commonly associated with phototoxic reactions. UVB is often referred to as the sunburn or erythema spectrum, and is regarded as being 1000 times more erythemogenic than UVA (Walker et al, 2003).
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