We rented a carpet doctor and used the pet stain shampoo thingy AMAZING. got out all the stains from everything not just bramble but also the time i dropped a bottle of wine on the floor and the time i dropped pizza on the foor (cream carpets!)

Only downside is you have to rent one for 24 hours - so not easy for the odd spillage and whoops. But deffiantely recommend it just to give the carpets a good clean once he's got the hang of things.