Yes it is awful but the first taste of blood and smell does intice nasty birds to come and have a go. We used to have white hens (not sure of their proper name) and they were awful to each other. However, a neighbour gave us some purple substance and the effect was amazing! And because the pecking stopped, it meant the poor bird healed.
We have now Rhode Island Reds and French hens and they are fine with each other. Actually, we have a very sick and close to dying hen, and even with her walking around half there, they did not attack her, but that is possibly due to no bleeding.
We also have some silver substance and this acts as a healing agent.
I am sorry because I do not know the names, and not sure if these are just french products. But it is worth asking your vet.
Suzanne
Often, I can bridge International waters when it comes to the chemical equivelents of products sold in different countries. Sadly, some chemicals are produced here (in the US) where they are banned from use, but still sold for use elsewhere. If you can locate the Brand Name(s) or the Active Ingredient(s), I see what I can find out ~'-)