You could try the one by the Eqyss - the people who do megatek - it is designed for putting on wounded skin etc - I use it as it is also good for sweet itch and itching. Get it from tailgator.co.uk.
One word of warning, don't every use the horse stain removers, if your horse has sensitive skin, I did once and she literally tried to scrape me off along a fence as she was so itchy.
hi piebald luckily he has more black than white on him and mainly drives but thank you for the advice. he is homeopathy which helps hugely we are lucky enough to have tim couzens near us.
I have to agree about the baby shampoo - and it works a treat, far better than most horse shampoo's and is much much cheaper. Johnson's is very good as is Sainsburys own brand and I've used them both on my horses over the years.
I know a lot of people who use baby shampoo rather than horse shampoo and I've never known one come up with any rash etc afterwards, even the ones with very sensitive skin.
My hairdresser told me that baby shampoo is really strong stuff and strips all the goodness from hair. It is not gentle at all, as it is designed to be a mild disinfectant to ensure the baby has very clean hair and no germs. This may be absolute rubbish, but I don't use it any more!
Echo the hibiscrub suggestion - I use this on the boy and it gets rid of all the scurff and dust, gives his little nicks cuts and scrapes a medicinal wash and leaves his coat gleaming!