Improvement of Arthritic Signs in Dogs Fed Green-Lipped Mussel (Perna canaliculus)

Abstract

Arthritis is a significant problem in both humans and animals that may occur at any age but is particularly common in older individuals. In dogs, both degenerative and inflammatory arthropathies may occur but the most common form of joint disease is osteoarthritis (OA4), a complex, progressive disease characterized by the degeneration of articular cartilage and by the formation of new bone (osteophytes) at joint margins. Inflammation of the synovial membrane may also be present in many cases of OA, but is a variable feature throughout the course of the disease. Conversely, synovitis is the major pathological feature of the inflammatory joint diseases, such as rheumatoid arthritis.

Degeneration of articular cartilage in OA is usually associated with some predisposing joint abnormality that produces focal areas of increased stress within the joint, resulting in accelerated turnover of cartilage matrix. Although both the synthetic and degradative activities of chondrocytes are increased, the balance is tipped toward matrix depletion with a net loss of cartilage matrix components. Joint enlargement may be evident in some affected dogs and is related to osteophyte production, joint effusion resulting from synovial inflammation and thickening of the joint capsule. Structural damage may exist for some time before clinical signs of OA are apparent, and most cases ultimately present with stiffness or lameness. Lameness, attributed to a combination of joint pain and restricted movement of the joint, may be gradual in onset or may present acutely following minor trauma or excessive exercise. A number of mechanisms are thought to be involved in the pathogenesis of joint pain itself, but one factor is the presence of synovial inflammation.

Dietary factors can potentially modify some of the underlying processes involved in arthritis, including modulation of the inflammatory response, provision of nutrients for cartilage repair and protection against oxidative damage. Where effective, dietary management may help to reduce or eliminate the need for conventional drugs, some of which are associated with adverse secondary effects. Shellfish supplements have been used as a traditional remedy for arthritis in humans and, in recent years, interest has focused on the potential benefits of a nutritional supplement prepared from the New Zealand green-lipped mussel, Perna canaliculus (1–3). Although green-lipped mussel (GLM) is known to contain anti-inflammatory components and other nutrients that may benefit joint health, the precise mechanism(s) of its actions are unknown. Heat processing of GLM has been shown to destroy its activity. Therefore, the processing of whole GLM and incorporation of the GLM product into food products requires special care and processing techniques to avoid destroying any efficacy of the final product.

In a series of clinical studies, we evaluated the efficacy of GLM powder in alleviating arthritic signs in dogs. The performance of GLM was investigated as a powdered supplement on top of a standard diet and when incorporated into one of two processed dietary products, a semimoist treat and a dry main meal diet. Both of these products used low-temperature manufacturing processes designed to retain the efficacy of the GLM.