Limping on back legs

Bit of an odd one really.
Tommy is almost 18 months now but for a couple of weeks I have noticed that sometimes he seems reluctant to put his back paws down when off lead. He runs fine, walks fine on the lead but sometimes when he's jogging he'll make a little skipping motion when he places his feet down. It's mostly his right one but now and again he does with his left one. I've checked his pads and his toes but can't see anything wrong.
I've rested him for a few days and he is still doing it. Do they get sensitive pads?
Any ideas?
Cheers guys

I would have though if it was the pads there would be some visible sore area? Perhaps a vet trip might be best? Xx

Problem is that they'll have to sedate him at the vets...he's had a bad experience there and is very fearful now   

Moo sometimes hops on her back legs - I just tell her to walk properly and she does - very odd girl! x

Vin has started this too but I have put it down to his front paws being sore but yes very odd xx

My friend has a staffy (Beau) that did the same and was diagnosed at the vets as luxating patella and required surgery to fix.  Luxating patellas which is just the name for slipping kneecaps. Its often a genetic thing where the knee joint doesn't form correctly and "fit" properly as one part is too shallow the other part pops out.
Its more common in some breeds than other and unfortunately the Staffy is such one of these breeds (so I am told).

If it is luxating patellas there are grades of it from 1 to 4. Grade 1 being the least and grade 4 being the worst. Grade one just often pops out and in again of its own accord, suddenly hopping on it and then running normally is a classic sign. Grade one depending on how often it does it usually doesn't always mean surgery. Grade 2 does sometimes as it can be prone to arthritic changes later that can cause problems. 3 and 4 always need surgical correction.

The vet can usually tell if it is luxating patellas on manipulation by what it does when they manipulate it out and then let go. I know the worst grade the knee is permanently out of joint and cant be manipulated back, the other grades full in between the two.

Other possiblilty could be a problem with her cruciate ligament sometimes they can tear worst cases, again if they do then surgical repair is needed.

Hip dysplaisa is another common problem, but I would have thought the symptoms would have shown before now.

These are worst case scenarios of hind leg problems, it could even be possible that he has got a bad sprain, strained ligament or pulled muscle even soft tissue injuries can cause problems too.

Hope the above information helps

All,
Thanks for the reponses.

Daz,
Thank you for taking the time to post your advise / experience. This is exactly why this forum is so valuable.

I will continue to monitor his over the course of the next week or so and if there is no improvement I will take him to the vet.

Thanks again everyone  

No problems, Mike, hope everything goes OK