Sunburnt ears remain a problem for sheep
The few hours of sunshine over recent days have supplied a welcome break from this wet summer. An interesting case this week had me out walking among a batch of ewe lambs in excellent pasture. The farmer was happy in general with his lambs this year, but some were showing an odd lesion on the ends of their ears.
We went from batch to batch and the more we examined them the more we noticed them all with the same degree of change to the skin on the ears. It was more visible in the younger animals, while the older ewes and rams were somewhat less affected. We put them through the crush and got a close-up feel of the most obvious cases. Despite the wet summer they were all showing signs of sunburn on the backs of the ears.
The only guy who seemed to have escaped altogether was a Suffolk ram with a black head and ears. The rest of the flock had the white ears burnt pink and a crusty lesion of various types, depending on the degree of burn.
It was hard to convince my farmer that we were dealing with sunburn as we'd only had one day of sunshine at that stage, as summer has been a washout.
It was all very fine to call it sunburn, but we then had to work out why it was afflicting this particular flock. Quite commonly in our grazing animals, we can get a condition termed secondary photo-sensitisation, or secondary sunburn.
It occurs if there is something affecting the liver or if there's an abundance of certain plants in the sheep's diet. One such plant is St John's wort, but there are other plants that may be extra plentiful from one year to the next. These plants can cause changes in the bloodstream leading to skin that burns more easily. But in this case, no such plants were found in the pasture.
Back to the liver, and if it is carrying a primary disease, it finds it difficult to carry out its normal functions. One such function is to deal with the by-products produced during the digestion of grass. If these by-products are not correctly broken down by the liver, the kidneys are not able to offload them through the animal's urine.
They begin to build up in the blood and become deposited in the skin. The skin then becomes extra-sensitive to normal sunlight because of the abundance of these normal grass or plant by-products. The skin will burn with even the lowest amount of normal sunlight.