My dog limps somtimes for no reason

"straight" refers to the angle of the legs and hocks...not the length of leg itself.
 
Basically when you see a dog you can look at the rear legs, from the side and see a backwards "L" shape with the angle...being the hock. In some breeds....German Shepherds for example....the angle is very sharp (looking like this >)...and in others, like the Chow....it is almost not there at all (looking like this I)....meaning that when the dog is standing normally...there is no "L" shape...but a "straight' line. This is ideal according to the written breed standard for the Chow, resulting in the "stilted gait" so prized. Of course many Chows (pet quality) do NOT have this straight assembly...that is why they are not shown. However the tendency, to be straight in the rear...IS in the Chow breed so even those with the "L" often have less angulation than other breeds might.

A bend to the hock...the "L" is natural and is seen in MOST quadrupeds...like deer, horses, and cats...it's basically a shock absorbing adaptation...straight rears break down more easily under the strain of running or jumping...because the knee and ankle are right under the thigh...the way a biped or upright being's are. []

My dog is show quality, blue, chow.
so i guess it would have been better in getting a pet quality because they don't have leg problems and dont suffer as much right?

I gotta go with Xebby for a minute on this. Sure, elbows and knees, but please don't rule out HD, either. Like Xebby, I'm in the midst of personal experience with it and I have 2 HD dogs who need serious surgery. (Do you feel better now Xebby?[])
 
It certainly can't hurt to have her checked out. Regardless of the issue--bruise or more--not dealing with it can worsen it.
 
On the plus side, my sister has had 3 Chows and none of them have had issues. Let's keep our finers crossed!

Oh wow, she has chows too. are they well trained? my dog will only obey me when he knows hes going to get somthing. like when i want him going into the crate, he'll start running all over the place and running away. how does your sis deal with this. does your sister's chows limp once in a while too?

Don't dismiss the possibility of pano, which is something he WILL grow out of.  The people that had Tyler for two months returned him, primarily I think because they thought he might cost them some money in vet bills.  She insisted that there was something wrong with his feet, legs or hips, when in reality the garbage she fed him made him grow too fast and he developed pano.  With Tyler, it's almost always back legs  and I worried about HD too but the vet xrayed and cleared that concern.
 
Even occassional limping deserves a vet check.

nope show versus pet quality is no guarentee the dog will be free of health problems.  In fact some dogs that are pets could have structure that is poor, making them incapable of completing the tasks the breed was designed for.  Chows are straight front and rear, they are not expected to be fast and agile.
 
If all things are equal (structure and health related issues) the differences between show and pet are essentially cosmetic.  Each breed has a specific list of disqualifying faults.  They are listed in the breed standard.

Hi, my pup was also limping for a while back, on his front leg.  We took him to the vet's, and after a couple of xrays he told us it was just pano.  That's just when certain parts of the pup grows faster than they're supposed to, and therefore causes the pup pain.  Since your chow is only 13 months, this might be a possibility.  I would definitely take your dog to the vet's to get him checked out.  Sometimes if you catch a disease early enough, it can save you a lot of money and heartache later down the road.

What's pano? What kind of garbage makes dogs grow faster? Does lack of exercise cause limping?

So does pano happen to a lot of dogs?

[align=left]Pano, as stated above, is when certain bones/joints are growing faster than other parts of the leg.  Lack of exercise has nothing to do with Pano, and a dog should NOT be exercised du ring a bout of it, as it can aggravate the "injury" and make it worse.  Generally, crate rest is perscribed.[align=left] [align=left]Pano partially has to do with genetics (as in, if somebody else in the line had o\it or somebody else in the litter had it, your dog could get it) but dogs DO grow out of it.  It is nothing more than growing pains.  Some ice and ibuprofen can help, but DO NOT get ANY medications without direction of your vet first![align=left] [align=left]If your dog is on a food that is too high in protein, this can also aggravate pano, and cause more trouble[align=left] [align=left]Pano is rather common, especially in large breed dogs.  My breed, the German Shepherd Dog, suffers from it a lot.  While they do grow out of it, it can hinder the show/performance career of an animal, as you HAVE to let them rest to get them back in top shape, or you could ruin them

Pano is short for Panosteitis.  If you google it you can find lots of information on the disease.  As Xeph stated, this is more common in large breed pups.

As to what is considered garbage food and what is not, you can find tons of information in the nutritions forum.  People have different views/opinions on what they consider is the best food for their dogs, and will advocate for different brands. 

When we brought our gsd pup in for the xrays, the vet told us that his diet was too high in calcium.  We switched to an adult food.  And the vet prescribed 10 days worth of Rimadyl.  The rimadyl helps relieve pain and reduces inflamation.  After the 10 days and a successful change of diet, our pup hasn't displayed any more signs of limping. 

However our vet did give us a different advice on exercise.  He said that as long as the dog wants to play/exercise, then we should continue playing like usual.  Normal exercise doesn't make cure pano any faster or slower than nature allows, so there's no reason to not let your pup to continue enjoying life.

^ Minty is right about exercise.  My post should have said "excessive or extensive exercise" not just exercise.  A romp in the back yard and what not is just fine, but you shouldn't be biking or jogging your puppy during bouts of pano because it can make the inflammation worse, and more crate rest than usual is a good way to keep it "under control"

So you suggest crating until I bring him to the vet. I'm planning on bringing him in on wed. I noticed today that when he was outside and i whistled for him, he didn't run to me. usually he runs. he was limping really badly.

When our dog had pano, he still ran and played like before.  It was as if we were the only ones who noticed that he was limping.  He rested a little bit more than usual, but otherwise he was still as active as usual.

By the sounds of it, pano might not be what your dog has.  I'm not trying to be pessimistic, since pano is probably the "best" thing your dog could have if hes limping(no need for treatment, goes away on its own).  If your dog is in a lot of pain, he will probably crate himself and rest.  And you should probably keep his walks short and not get him excited over anything. 

I hope all goes well at the vet's.  And keep us updated!