Sunburn

Occurrence: Worldwide.
Age affected: All ages.
Causes: Non-pigmented skin; lack of shade and wallows.
Effects: Red tender skin, refusal to mate, abortion, embryo losses.

Causes

Sunburn is common when white pigs are exposed to the sun for the first time. It is most serious in young pigs but may occur in adults. The effects are due entirely to the ultraviolet element of the sunlight which causes damage to the skin and gives rise to inflammation followed by scabbing and necrosis.

Mode of transmission

The condition is not transmissible.

Clinical signs

White pigs or pigs with white patches are most seriously affected. The animals may have been put outdoors without shade in the sun or a period of dull weather may have prevented exposure to the sun and acclimatisation. The white parts of the body become reddened, oedematous and irritable and the animals appear to be in pain. The pain produced may be sufficient to prevent mating and the prostaglandin release may result in resorption of embryos and return to service. Some degree of sunburn may occur in sows kept outdoors even when shade is available, but it rarely goes beyond reddening of the skin.

Inspection of the pig confirms that it is white and that exposure of the skin to ultraviolet radiation has occurred. The presence of reddening blistering and peeling of skin on the dorsal surface and flanks is very suggestive and a history of exposure to sunlight provides confirmation. Few conditions can be confused with sunburn. Photosensitisation to parsnip or celery leave may be confused with this condition. The effects of heat exposure alone are different as they do not involve the epidermis.

Postmortem lesions

Pigs rarely die, but if examined at slaughter the skin lesions would be characteristically restricted to the superficial layers of the skin and might even be scraped off during processing. unlike the deeper lesions caused by fire or electrocution.

Treatment and prevention

Pigs with sunburn should be given shade and access to a wallow. This will allow cooling. It may be possible to coat the skin in neutral oil to reduce the burning. Animals in pain should not be mated as mating is unlikely to be successful. Ensure that pigmented breeds such as Duroc are used outdoors so that sunburn does not occur.