Six weeks ago i aquired a rescue border collie. He is a lovely boy and when he first arrived his coat was matted and dull. After lots of gentle brushing the matts are gone and 2 weeks ago his coat looked beautiful, very full and shiny. Now his coat looks a shiny but he is losing an awful lot of coat. he is not itchy, he is up to date with flea treatment and he is losing masses of undercoat. His trousers for want of a better word look a lot thinner and his mane is a lot less full and he generally has a lot less hair. No bald patches though. He is 16 months old and entire at the moment as i don't want to castrate him until he is 100% settled and if he stays as nervous as he is i may leave it for quite some time. He is my first collie only ever having had poodles or lurchers with not much coat so i don't know if this is normal or not. Do they have a junior moult or is there something else going on? He has been to the vets and they can find nothing wrong with his skin but they cannot tell me if this is normal or not.

Sounds like he is just moulting - my carpets are currently  totally different colour form normal due to the amount coming off my dogs and my boy looks almost bald in places he has lost so much his 'trousers' are definitely lacking their usual substance :D

Agree the weather this year has played havoc with coats and mine have been almost permanently moulting since March, rather than the usual three or so weeks to have a full moult.

I was just saying to someone today that River has just gone through a full moult - she's never done it at this time of year before.  Yet Saffi - who normally just moults heavily all the time - is barely shedding at all.  It really is all over the place at the moment!

Yes Border Collies do have a junior moult where they look like scraggy whispy haired smooth coat LOL. Did he come from a kennel situation? If he did bringing him inside will also be having an effect.

Thanks for all the replies so far. He didn't come from a kennel situation as such- he was kept in a yard with a number of other dogs so he was outside. Glad to hear i should hopefully get my pretty boy back again.