We've had Romeo for a year now, and sometimes when he's walking,  he will limp for several paces.  It's his left hind leg and seems to be the hock area.  I've noticed it when he does his usual happy trot, but not when he's running or walking at a slow pace.  It looks as if he's skipping, it's actually kind of cute.  The vet couldn't find anything wrong with him, and it doesn't seem to cause him any pain.  Is this something common to Rat Terriers?  I just want to know if it will degenerate further and if there's anything we can do to help him.  He's a pet, not a show dog, so the limp doesn't matter to us, we just want him to be healthy and happy. 

Did you see my thread Yaz is limping? She will be 2 this summer and she just started this last night. Nothing happened she just started hobbling around, then shes fine, then she hobbles. She isn't whing or anything.

I think it sounds like Luxating Patella.  I just posted something about this on Yaz's topic.  It is when the kneecap slips out of the groove that it sits in.  It is not uncommon in many small breeds.  It can get worse.  You might want to ask your vet to confirm about Romeo's patellas.  How old is Romeo?  If he is still young, you may want to wait until he is at least 2.  Someone, I think Jeff, told me that in puppies sometimes the vet does more harm trying to move the kneecap.  You may also want to try to keep Romeo's weight down as he gets older as this can make it worse.  Many dogs go about just fine with the occasional skip.  Some dogs will have to have surgery to correct the problem.  There are people here who know a lot more than me about this.  My dog has a luxating patella, but as of now, she hasn't ever had a slip or problem with it.  Good Luck!

Thanks for the help.  Romeo's 2 years old, and not overweight.  We walk twice a day so he's in great shape.  The limp is only occasional, so I'll just keep an eye on it. 

It sounds like a luxating patella.  I think there are four levels of severity.  The vet doesn't have to do xrays,  they can tell by touch, by turning and twisting the leg and seeing how much extra movement there is.  The vet I went to said if the dog is under 20 pounds, he would not recommend surgery unless the dog is in pain.  If it never progresses past the skip step stage,  then most dogs  can just live with it.  As in Rattagans case,  dogs with luxating patellas are more prone to ligament injuries as well, which will require surgery.  The vet told me to make sure the dog gets plenty of exercise to keep the leg strong and to keep their weight down, as it puts excess stress on the joints.  

It seems to be a mild case of LP.  Our vet gave Romy a thorough check up, and even when working that leg, it didn't slip out of place.  So we'll just leave it alone.  We live in a hilly neighborhood and walk twice a day so he's in great shape.  If I may brag a bit, the vet said Romy's the nicest Rat Terrier she's ever met.  Romy was so pleased with the compliment that he walked right to the end of the exam table and gave her a big kiss!