Yes it is safe. One of my dogs (german Spitz)has a collapsing trachea(windpipe) and when she gets hot she gasps for air. I was informed by the vet that she wuold not last for very long. I started her on glucosamine and Chrondroitin. quarter teaspoon on her food every night. That was two years ago. An old Bichon Frise is having trouble with a slipping patella, again G & C has helped. The veterinary products are very expensive.
I get tablets (on offer from the Sunday Mail)and grind them up in a coffee grinder. The older dogs anyone over 7 years of age get it automatically.