The aim of this study was the evaluation of two feed supplements, Canicox (R) and Dexboron (R) flavour tablets (produced by NutriLabs, Fa Greencoat Ltd, Monmouth, UK) with respect to their influence on lameness in dogs suffering from osteoarthrosis. 29 adult dogs from different breeds suffering from cubarthrosis (elbow) or coxarthrosis (hip) were used in this study and allotted randomly to two groups. Group A received Canicox (GA; I tablet/10 kg body weight q 12 h PO for 7 days, followed by I tablet/10 kg body weight q 24 h until day 28), group B received Dexboron (GB; I tablet/10 kg body weight q 12 h PO for the first three days followed by I tablet/10 kg body weight q 24 h PO) Both medications were given for 28 days. The lameness evaluation was done by measuring the ground reaction forces on the first and on the last day of treatment. In group B, the measurements were also done on the third day of supplementation. The following parameters were evaluated for the relevant pair of limbs: maximal vertical force (PFz), mean vertical force (MFz) and vertical impulse (IFz). A symmetry index (SI) was calculated for these parameters that expressed the diversion from absolute symmetry in percent. In GA, this diversion was between 8.6 % (MFz) and 11.1 % (PFz); in GB, it lay between 7.3 % (MFz) and 9.2 % (IFz). A significant improvement of the symmetries for the MFz and the PFz were already seen on the third day of supplementation in GB, but not for the impulse values. On day 28, an improvement could also be demonstrated for the impulse values. There was no further improvement in MFz and PFz. GA showed on day 28 a statistically relevant improvement in the MFz and in the PFz. However, there was no statistically significant improvement of the impulse values in this group. Both products exerted a positive effect on the patients' movement characteristics, although the lameness could not be entirely cleared in all the dogs.