EXERCISE INDUCED LEG TREMORS

Question
AFTER 15 MIN OF FETCHING THE TENNIS BALL MY JRT "CHICO" TAKES HIS BALL AND LIES DOWN BECAUSE IS HIND LEGS TREMOR LIKE MUSCLE SPASMS. HE WAITS A FEW MINUTES THEN RESUMES PLAY. HE IS 2YRS OLD AND THE TREMORS SEEM TO HAVE GOTTEN WORSE THIS LAST YEAR. I THOUGHT HE WAS JUST FATIGUED BUT I AM CONCERNED. ANY ADVICE?

Answer
Hi Christy,

I'm sorry but it could be many different things. It's so hard to say exactly what it is without seeing it but I'll give you a couple of things to think about.
I've seen the leg tremors, my own dogs legs shake even when they are just standing still and putting pressure on them.
It's not a constant thing, it comes and goes.
My vet told me long ago it's just a jack trait. It hasn't caused them any pain or weakness - it looks scarier than it really is.  
After running at top speed for 15 minutes even the best athletes legs can get "shaky". If he sits and regroups and then resumes play, he knows his body and his limitations. I think you're right and that maybe his legs just need a rest. I have seen this happen a lot with the agility jacks. Their leg muscles just work so fast and so furious that they literally cause a sort of chemical reaction to the muscles and they react by shaking. Ever watch the tongue shake when it's panting.....  it's sort of like the same shake. It's just a natural reaction to stress on the muscles.   
But... there are two kinds of trembling. The one I think you're talking about, the legs just shake.
The other kind would be spasms - like the leg jerking open and closed. Spasms are different than shaking. If his legs are spasming and he seems distressed it may be time to take him to the vet to be looked at.  
I've seen it so much that I don't think your dog's case is something to worry about, but as with anything that is concerning or getting WORSE, you'd be better off having them checked.  Sorry not a more definitive answer, but that sort of thing is tough to call without seeing it.
Best of luck!