My little lad got his first critique today, and it was good (well, better than expected), but it said he was long in loin and I don't know what this means.  Is it a fault.  He was 9 months old at the time if this helps at all.

Long in loin mean he's got a bit too much length between ribs and pelvis. This can lead to a slight weakness on the topline in maturity. It's more excusable in bitches, where it gives more bodyroom for carrying a litter.

Thank you

Would definitely be a fault in my breed which is required to be square in outline with a short broad deep loin to give it strength and the ability to dodge easily  A dog can be square but have a long loin and short rib.  This means they are not as strong in their back and don not have the chest room for a good set lungs which they need for stamina.  So these requirements are generally functional not just aesthetic.  As JG has said most bitches are a touch longer in this area to allow for puppies, and some very short loined bitches can have problems in whelping.

I would say tho that at only 9 months there is plenty more time for development dependant on the breed?! My boy was described this way when a youngster and now his chest has developed and his ribs have sprung he is not long at all

It very much depends on the breed tho, some call for longer loins and some for short.  If the breed standard calls for short loins then it's a fault, but at nine months it could be due to a lack of maturity.  Best way to find out is to check the breed standard ;)  And don't forget, it's only one judge's opinion, another judge may have a different opinion.  Time to worry is when they keep mentioning it ;)

"My boy was described this way when a youngster and now his chest has developed and his ribs have sprung he is not long at all"

I thought that basic bone structure wouldn't change even with maturity?  If he is long in the loin how a rib spring could change this I don't know?   Maybe someone could enlarge on this?

My breed is supposed to be short coupled although one champ show judge wrote this down as a 'fault' against my dog comparing to the one he placed first!

Just to confuse you, some judges will refer to it as being 'long coupled' or 'short coupled'. Basically, it's how much of a gap there is between the last rib and the pelvis joint. The acceptable length varies from breed to breed. In my breed the ideal would be about 4 fingers width in an adult. Ask a breeder who breeds good examples of your breed what the optimum gap should be for a dog of 9 months, preferably in finger widths as it's fairly easy to use this method. This will give you a rough idea if there are other factors making him look long coupled or if he really is long coupled.