dogs frequent limping

Question
Hi Dr. Fry,

I'm a little concerned for my Great Dane / Shar pei mix dog, Buddy.  Lately Buddy has been developing limps on any of his four legs more frequently, it seems, than normal.  Whichever leg it is, the limping seems to be pronounced at first, then subsides after 1-3 days.  His gait will be normal for a time, then, maybe a week or two later, I'll find Buddy limping again.  I think the limping is partly due to all the sharp or prickly stuff that litters Average city streets and sidewalks, and I don't know how to protect him from that except to avoid the worst of it if I can see it.  Buddy also seems to have pretty low endurance for a dog of his age (3 or 4 years old), although he does weigh 100 lbs. (He's not overweight, according to the last vet we saw.  His shape matched the healthy ones shown on the charts.)  When I walk him, buddy has a hard time heeling at first, but by the end of the walk,  he has slight trouble keeping up with me.  Even though Buddy can't easily keep up at the ends of our walks, he never seems particularly tired.  Sometimes he'll beg for another walk right after we return from the first.  (I'm 6'2" and I do walk briskly)  He's been chewing at his front paws a lot lately, and I notice that his most recent limp is on his front right paw.  This all reads kind of disjointedly, I know, but I don't know what to attribute his limping to.  Should I be shoeing his paws or otherwise protecting them from concrete?  Is this the possible beginning of a problem which could cripple him?  What warning signs should I look out for, specifically with the limping?

Answer
I would have him checked for Lyme Disease as this can cause limping.  Certainly large breed dogs are more prone to joint problems, and he may need to have x-rays to determine the exact problem.

In the meantime, I would recommend putting booties on him to walk to protect his feet and reduce the length of your walks.  Start him on Glucosamine 2000 mg twice a day, MSM 2000 mg twice a day and Ester C 1000 mg twice a day to help protect and lubricate his joints.  

You can also try soaking his feet in epsoms salts in case he did step in some glass.