Our friend Tony told me about the flock of sheep fed on oil-seed rape, when it first became a popular crop in Britain. (It might have been in 1976 that famously hot dry summer.) The sheep gained weight like never before but lost their ears! It was a mystery.
Oil seed rape field curtesy of Bayer Crop Science UK CC BY 2.0
Photo-toxicity is something I learned about in another life when a lady gardener showed me the livid, blistered scalds on her arms, as if she had been whipped with a red hot flail. In fact she had been lightly brushed by the cut, sappy ends of giant hog weed, angelica and cow parsley that had taken root and flourished amongst her parsnips that hot summer and which she had been cutting down.
Phototoxic chemicals, which occur in all these plants, increase the reactivity of the skin to ultra-violet and sometimes visible light – they are the opposite of sun screen and can produce the most bizarre patterns of sunburn. You can get them onto your skin directly, like the sap, or be effected by eating them, as with the light sensitivity that can occur with certain drugs.
Bergamot oil is another phototoxic agent, giving a puzzling blistered burn on the neck of a very smart but distressed lady who did no more than spray herself with expensive perfume on a sunny day.
I think that the sheep with the missing ears got such bad sunburn on their ears (their least woolly part) after eating or brushing through oil seed rape that they ultimately lost the tips of their ears– like our lamb here.
Two of our triplets this year seem to be effected. They are the small ones who have had less milk and, early on, foraged more widely, nibbling in the hedgerow and tasting all sorts of plants at an earlier age than usual, when their hair was thin and their skin sensitive. The bigger one has gained weight but has lost his ears!
The little one has done better, now we have worked it out, and she has had treatment and gets my sun screen (factor 20) liberally applied on sunny days!
Twts (they never have names!) She’s better with antibiotic, steroid and sun-screen
Whatever next?
dianaashworth 
The lamb looks so cute with blue ear! Reminds me of when we used gentian violet and iodine as skin prep prior to abdominal surgery – multi-coloured striped abdomens!