I rehomed a 14 month old cavalier king charles, but his urine stinks......?

I have the same dog . it does sound as if he was'nt trained when you got him . they are the easiest dog in the world to train so I'd advise to start again with it . the smelly wee I've never encounted but as the others have stated it might be an infection . as you've said these dogs are fantastic with kids so much so that we're getting a second one for christmas so it means that the training starts again for me but it actually only took about 2 weeks with the dog we have now. I just watched him constantly and every time that he went to the toilet I just lifted him onto newspaper on the floor . moving the paper closer to the door each day . then I started taking him outside and all this only took about 14 days. good luck with it .