Although it is well recognized that dietary supplementation with fish oil improves clinical symptoms in dogs suffering from osteoarthritis, the molecular basis for the dietary benefit is not yet completely resolved in dogs. This study was designed to further clarify how polyunsaturated fatty acids (PUFA) affect key factors of cartilage degeneration in a canine cell culture system mimicking osteoarthritis. Canine chondrocytes were incubated either without or with 10 μm of eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), arachidonic acid (AA) or 3.6 μm ibuprofen (Ibu) as positive control for 6 days. After the supplementation, cells were stimulated with 10 ng/ml interleukin-1β (IL-1β) for another 48 hr to induce osteoarthritic changes, or left unstimulated. We analysed fatty acid uptake via gas-liquid chromatography, nitric oxide (NO) production via Griess assay, prostaglandin E (PGE) production via ELISA and relative gene expression of several cartilage matrix proteinases, inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 via RT-qPCR. After supplementation, the chondrocytes rapidly incorporated the PUFA into their fatty acid pools. The stimulation with IL-1β caused a marked increase of most of the inflammatory markers measured. N-3 PUFA EPA reduced IL-induced gene expression of iNOS and corresponding production of NO. N-6 PUFA AA also decreased iNOS and NO, but furthermore lowered gene expression of matrix metalloproteinase-3. On the other hand, AA upregulated the aggrecanase ADAMTS-5 and augmented the release of PGE. The effect of n-3 PUFA DHA turned out to be negligible. Our results reveal molecular mechanisms by which PUFA affect degenerative joint disease in dogs. Of particular importance is that not only EPA but also AA decreased several inflammatory markers in our model. Thus, we conclude that an appropriate balance of both n-3 and n-6 fatty acids deserves more attention in dietary interventions.

OBJECTIVE To determine effects of transforming growth factor (TGF)-β and interleukin (IL)-1β on inflammatory markers in cultured canine chondrocytes to clarify the role of these cytokines in osteoarthritis of dogs. SAMPLE Pooled chondrocytes isolated from the stifle joints of 4 adult dogs. PROCEDURES Chondrocytes were isolated, cultured, and frozen at -80°C. Pooled cells were incubated in medium with or without TGF-β (1 or 10 ng/mL) and subsequently stimulated with IL-1β (10 ng/mL). Concentrations of nitric oxide (NO) and prostaglandin (PG) E were measured in culture supernatants. Gene expression of matrix metalloproteinase (MMP)-3, tissue inhibitor of metalloproteinase (TIMP)-2, inducible NO synthase (iNOS), and cyclooxygenase (COX)-2 was quantified by use of real-time quantitative PCR assays. RESULTS Stimulation with IL-1β increased gene expression of all inflammatory markers, except for TIMP-2. Incubation with TGF-β resulted in a significant decrease in MMP-3 and TIMP-2 mRNA concentrations but had no effect on PGE and NO concentrations. For cells treated with TGF-β followed by IL-1β, concentrations of PGE and NO were lower, compared with concentrations for IL-1β control cells. Furthermore, IL-1β-induced gene expression of iNOS, MMP-3, and COX-2 was downregulated. However, the IL-1β-induced downregulation of TIMP-2 gene expression was partially restored by pretreatment with TGF-β. CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that IL-1β increased the expression of inflammatory genes and mediators, and TGF-β largely attenuated the IL-1β-mediated inflammatory response. Therefore, TGF-β might be a novel target for use in the prevention and treatment of cartilage breakdown in dogs with osteoarthritis.

To determine the effect of the Christmas period on food intake and rates of weight loss in obese dogs on weight programmes. METHODS This was an observational retrospective study of 38 obese dogs attending the Royal Canin Weight Management Clinic, University of Liverpool. Weight loss programmes of all dogs spanned the Christmas period, and owners had completed a food diary, which enabled energy intake from extra food (i.e. treats and table scraps) to be calculated. Rates of weight loss and energy from extra food were compared across three periods, comprising Christmas (21d starting the weekend before Christmas), pre-Christmas (21d immediately before the Christmas period), and post-Christmas (21d immediately after the Christmas period). Friedman's test (with Conover post-hoc comparisons) was used for statistical analysis.