The results of study on race and show horses was conducted here in the U.S. a few years back re: the effctiveness of glucosamine/chondroitin in treating joint damage and pain.
It may contain some applicable informaiton:
"Dr Rodgers examined the horses if the trainer complained of soreness, improper gait transitions or lack of jumping impulsion. She evaluated the gait, and used flexion tests, radiographic changes and intra-articular anaesthesia to determine the source of the pain. If a diagnosis of distal tarsal pain was confirmed she injected the tarso-metatarsal and distal hock joint with corticosteroids and hyaluranon.
She found that the number of times she needed to inject the joints fell while the horses were receiving the glucosamine / chondroitin supplement. The frequency of distal tarsal joint injections fell from an average of 1.7 injections a year when the horses were not receiving glucosamine/chondroitin, to 0.85 injections a year once they were receiving the supplement. There was a marked reduction in frequency of injections after 5 - 8 months of treatment.
“Distal tarsitis is a progressive disease. It would be expected that with increasing age and the demands of show horse performance the horses would need more therapy, not less” Dr Rodgers points out. “In the light of this, the overall drop in the number of injections required and the decrease in injection frequency over the eight year study period can be seen as an even more convincing argument for the beneficial effects of long-term supplementation.”
Regular, twice daily administration of a combined glucosamine / chondroitin supplement resulted in longer duration of soundness and fewer joint injections. Six to eight months of regular administration were needed before the favourable response was seen."
For more details see:
Effects of oral glucosamine and chondroitin sulfate supplementation on the frequency of intra-articular therapy of the horse tarsus.
M R Rodgers
International Journal of Applied Research in Veterinary Medicine (2006) 4, 155 - 162.