Use of gold implants as treatment of pain related to canine hip dysplasia – A review concerning method, mechanism of action and clinical effects of gold bead implantationIn her PhD thesis, Deisenroth provides an overview of publications on gold implantation primarily in dogs with hip dysplasia – a congenital developmental dislocation in the hip joint area after birth – in the period up to 2010, supplemented by a few relevant publications from the field of human medicine. These deal with methods, investigations and possible explanations regarding the effect. Due to the length of the publications, a few interesting hints are given here rather than a summary. Deisenroth concludes, amongst other things, that the potential of the anti-inflammatory effect of gold implants is of primary interest for the therapy of osteoarthritic diseases in dogs. Deisenroth also refers to the development of the effect of gold implantation over time, as described in the studies. It is not yet possible to say at this point in time whether becoming embedded in the tissue, which potentially increases over the course of time, limits the duration of the release of gold ions, thus limiting the possible effects of gold implantation over time. It is also interesting that the release of gold ions seems to depend on the degree of inflammation in the surrounding tissue and that only low amounts of gold ions are released from gold implants in non-inflammatory tissue. The publications exhibit differences in the methodology of gold implantation, the kind and extent of the investigations, the observation period as well as evaluation criteria; this makes a comparison and assessment of the results more difficult. Some insert gold implants at acupuncture points (called “gold acupuncture”), others insert them at non-acupuncture points in addition or instead (called “gold implantation”). The number of points as well as the number of gold particles inserted per point vary, and likewise the number of animal patients. Three double-blind, placebo-controlled randomised studies, three retrospective, non-blinded studies and five case studies were used. In the last two categories, more positive results of treatment have been published than in the first one, and also on the websites of vets. Deisenroth considers it possible that the adaptation of the gold implantation to the individual pain symptoms may in these cases influence the results of the treatment. Various approaches towards explaining the effect of gold implantation are discussed. A permanent acupuncture effect of gold implants at acupuncture points appears to Deisenroth to be unlikely as an explanation, since after repeated stimulation a tolerance to the stimulus has been observed and, moreover, the gold implants are placed in tissue far from the acupuncture points and near the joint modified by inflammation. After the release of gold ions in the tissue in the course of phagocytosis, macrophages possibly build aurocyanides and release them. Aurocyanides can inhibit the release of reactive oxygen compounds by neutrophil granulocytes as well as phagocytising macrophages. This way less myeloperoxidase is produced, which in turn catalyses a reaction from which hypochlorous acid emerges, which, in case of arthritis, damages the articular cartilage. This is why the myeloperoxidase activity contributes largely to perpetuating osteoarthritic processes.
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