My vet put Kodi on Glucosamine When he was quite young, just because he did agility. I have Panda on it already.
Unfortunately, it is NOT only "couch potato-type dogs who rupture their cruciates. ALL the dogs I know who have ruptured cruciate have been fit, sports dogs. That doesn't mean it doesn't ALSO happen to "pet" dogs, but I know a double handful, and they have all been sports dogs, and they have also all, eventually had the second leg go. We joke that then they re fine, because they are "out of legs".
The only non-sports dogs that I know, happen to all be Havanese... Two had partial tears that recovered with conservative treatment, and then poor Scout, here on the forum. I DON'T think that's because it's a big problem in the breed, however, it's just that I know more people with Havanese than any other single breed.
I was also told by my vet, who has an integrative practice, and is also a magician of a chiropractor, that teaching my three Havanese to "sit pretty" was really good for their core strength. She encouraged me to get them all doing it... especially Kodi, because of his age. He is finding it hardest to learn, not surprisingly! I can lure the girls into that position... I have to help him with a hand on his back to get him up and stable. The very told me only to ask him in tiny bits for now, because it is really hard work for his muscles.
My vet also discourages EVERYONE from doing serious disk-dog stuff with their dogs. She says she sees more injuries from that sport than any other. In ALL breeds. She isn't talking about casually tossing the disk around in the backyard, though. The real, COMPETITIVE disk dog stuff is CRAZY!!!
I think it's great that Shama checks out as OK to do what you want to do with her. I WOULD consider finding a good chiro person to work on her if her hips are sore, though. It MIGHT by arthritis, but it MIGHT also be something our of alignment or a muscle problem. It's likely that someone in your training center can send you in the direction of someone. Kodi gets chiro every 6-8 weeks, just to keep him tuned up, after a pretty significant muscle injury when he was about 2 1/2. I don't like him to get uncomfortable and THEN respond. I'd rather stay ahead of it, since I do ask him to work hard. The girls get an occasional tune-up, but haven't shown any signs of trouble.
Dee Dee, I can understand your fear of a Doxie getting hurt in agility... The instructors around here usually won't even let one in a class. The risk is too high for them. Heck... walking around is risky for a Doxie! LOL! But it really is not a problem for the average, soundly built Havanese. (those with bad fronts are a different story) The dog who convinced me to get involved with this breed recently turned 15, and is still running agility!
Of course you don't want dogs of any size or shape launching off high equipment, but that's why it is important to teach good contacts. We are even careful about that... My dogs ONLY do running contact, because I don't want any spinal compression with hard stops at the bottom of contacts. No 2 on 2 off for us!
As far as "collapsing" on walks, Kodi does it sometimes too... BUT he ONLY "collapses" on warm days, in the shade, on nice green grass... stretched out on his belly.
I am QUITE certain it is heat, not pain.