What is the evidence? There is only very weak clinical trial evidence to support the use of glucosamine and chondroitin supplements for osteoarthritis in dogs.

摘要

While vaccination can involve a substantial investment, particularly among large-scale egg producers, Dr. Hofacre thinks many producers want the economic fairness that would come from a requirement that all hens be vaccinated. He estimates that it costs producers about 18 cents to vaccinate each hen, and producers do not benefit directly from that "insurance policy" as they do with use of vaccines that improve hen health.