An open multi-centre veterinary clinical trial, comparing conditions before and after treatment with a herbal dietary supplement consisting of a natural resin extract of Boswellia serrata, was conducted by 10 practicing veterinarians in Switzerland. This traditional plant-based supplement is known for its anti-rheumatic and anti-inflammatory properties. 29 dogs with manifestations of chronic joint and spinal disease were enrolled. Osteoarthritis and degenerative conditions were confirmed radiologically in 25 of 29 cases. The resin extract (BSB108, product of Bogar AG) was administered with the regular food at a dose of 400 mg/10 kg body weight once daily for 6 weeks. Already after two weeks of treatment, an overall efficacy of the dietary supplement was evident in 71% of 24 eligible dogs. A statistically significant reduction of severity and resolution of typical clinical signs in individual animals, such as intermittent lameness, local pain and stiff gait, were reported after 6 weeks. Effects of external factors that aggravate lameness, such as "lameness when moving" and "lameness after a long rest" diminished gradually. In 5 dogs, reversible brief episodes of diarrhea and flatulence occurred, but only once was a relationship to the study preparation suspected. Because quality and stability of the resin extract were ensured, these data suggest that a standardized preparation can be recommended as a herbal dietary supplement providing symptomatic support in canine osteoarthritic disease.