Hi guys, just looking for a bit of advice...

About 8 months ago one of my boys had surgery for his second cruciate, the op that puts in the metal plate. I gave him house rest for approx 6 weeks and started very gentle short walks. It took him a good 4-5 months for the lameness to go away but after that he was 100%. 

About a month ago I took him for a walk, about 30 minutes across our fields, he was off the lead but he is not very energetic just trots and maybe a canter for 30 seconds. He was fine during the walk and for 2 hours after. I went out for a couple of hours leaving him in the lounge and when I got back he was so lame he couldn't put his foot down. He's not a baby but I could see the pain in his face

Anyway he's been to the vet for x-rays and they show nothing!!! No damage, no problem with the plate and no answers. They say it could be the knee orhis hip dysplasia. I know in my heart it is his knee, he is such a gentle dog but he looks worried and licks his lip when I touch him near the plate. All they say is that they can open him up for a look but he's had multiple surgerys in his 4 years so I would rather they knew what it was before he has another procedure.

Don't have much confidence in the vet at the mo so would welcome any advice....

Many thanks, Mel & Balto