Sunburn can be a painful problem

St Johns Wort, a wild perennial plant.
St Johns Wort, a wild perennial plant.

Standing on top of The Cheviot a few Saturdays ago, marshalling the Chevy Chase fell race for four hours, soaked to the skin and freezing cold, my mind was a long way from thinking about sunburn.

However, we have seen several cases of ‘sunburn’, also known as photosensitisation, in farm animals recently, particularly cattle.

Some of the causes listed above are genetic so often it is best not to breed from affected animals again, or their offspring.

As with humans, it isn’t necessarily just the bright sunny days when this problem occurs – UV rays can be just as harmful when it’s cloudy because animals are less likely to seek shelter.

The problem is pretty easily diagnosed.

The skin, normally white patches, appears ulcerated and scaly, and generally the areas pointing towards the sun are most affected, ie around the spine, ears and face, but also the udder if they have been lying down.

Sometimes the affected animals seem completely unaffected, but we treat mainly to prevent a secondary infection, and to provide pain relief.

Obviously the sun is essential for photosensitisation to occur, but we usually see only individual animals affected where a chemical in the body has made the skin sensitive to sunlight.

This chemical builds up due to either a defect in the animal’s metabolism of its own red blood cells or plants such as St John’s Wort for cattle, or Bog Asphodel in sheep.

It can also be seen in animals with liver failure, or due to a localised reaction to the sap of some plants.

When treated with pain killers, antibiotics and shelter from sunlight, most animals recover within a few weeks.

Similarly to humans, the affected areas peel off and new skin grows underneath.

Problems can occur if the cow is feeding a young calf and her udder is affected as often she is too painful to allow suckling.

Some of the causes listed above are genetic so often it is best not to breed from affected animals again, or their offspring.

So whilst most of us look forward to enjoying some lovely hot, sunny summer weather, spare a thought for the animals affected by photosensitisation, who are banished to the shady sheds for the next few months.