NUTRITION
nium above requirements is not likely to confer addition benefits under normal training conditions,” she said. And too much selenium can be toxic. In 2009, 21 polo ponies died after an overdose of selenium used to help muscle recovery. For vitamin C, there is plenty of research available, but the results have not demonstrated a clear benefit in reducing oxidative stress. There is no dietary requirement established for vitamin C, and it is assumed that synthesis of the vitamin in a horse’s body is enough to meet their needs.
Immunomodulation with Fatty Acids
Fatty acids have long been known to influence the immune response through several mechanisms, including gene expression, cell signals, cell membrane composition and by serving as a substrate for more
New AKI Marker Found Symetric dimethylarginine (SDMA) concentrations seem to correlate with creatinine concentrations in dehydrated horses, and they could be a biomarker for kidney injury. A prospective cohort study explored the correlation between SDMA and the level of dehydration against traditional renal biomarkers, as well as its prognostic use as a biomarker of early renal injury. Serum SDMA, creatinine and urea concentrations and renal function analysis were measured in 41 horses with dehydration at 4 points until 48 hours after admission. Horses were grouped into mildly, moderately and severely dehydrated groups. SDMA concentrations at admission correlated with creatinine concentrations (r=0.412; P <0.001). Differences in SDMA concentrations at admission were detected among dehydration levels but not between survivors and non-survivors. Significant correlations of SDMA concentrations with other markers of renal function analysis and shortterm outcome were not seen. Only 1 of the horses developed acute kidney injury, which made the evaluation of the predictive value of SDMA difficult. Use of SDMA as a prognostic biomarker warrants further research, the researchers said. MeV
For more information: Lo H-C, Winter JC, Merle R, Gehlen H. Symmetric dimethylarginine and renal function analysis in horses with dehydration. Equine Vet J 2021. https://beva.onlinelibrary.wiley.com/doi/10.1111/evj.13484
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Issue 9/2021 | ModernEquineVet.com
bioactive molecules. Both omega-3 and omega-6 fatty acids are important to include in a horse’s diet in the proper balance. “Ultimately, it’s the balance of omega-6 and omega-3 fatty acids in the body—or really within the cell— that determines the overall response,” she said. Prior research has shown that omega-3 fatty acids can reduce markers of inflammation. However, prior research has also shown the opposite. “It generally takes a high supplementation rate— anywhere from 50 to 75 mg/kg of body weight—to elicit changes in markers of inflammation,” Dr. Warren explained. “That is much higher than is typically recommended by supplement companies, and probably too high to be economically sustainable for most horse owners.” She also explained that although omega-6 fatty acids are often maligned, they are by no means the villain in the fatty acid saga. “There have been claims that omega-6 fatty acids can cause inflammation, but there is little support for this in the literature.” In one of her studies, Dr. Warren found that yearlings supplemented with a high-fat source of either fish oil or corn oil—which is rich in omega-6—had similar reductions in the inflammatory marker PGE2 when compared with a diet where no fat was supplemented. “From a clinical standpoint, most people are interested in supplementing omega-3 fatty acids to horses with inflammatory conditions such as osteoarthritis,” she added. “A relatively high amount of EPA [eicosapentaenoic acid] and DHA [docosahexaenoic acid] from fish oil was shown to alter the fatty acid composition of synovial fluid in several studies, but it’s been a mixed bag in terms of having an impact on inflammatory markers or clinical outcomes.” She added that omega-3 supplementation in healthy horses typically has no benefit. The American College of Veterinary Internal Medicine has recommended 1.5 g of DHA for the treatment of inflammatory airway disease, but those recommendations are quite lower than the dosages that affect inflammatory markers in the literature, according to Dr. Warren. Omega-3 fatty acids appear to have the greatest impact in horses that have a heavy inflammatory load, which echoes some of the effects that are found in antioxidant nutrients. “It does appear that the longer-chain omega-3 fatty acids, such as EPA and DHA and their sources, are more effective than supplying omega-3 as the parent fatty acid alpha-linolenic acid. However, there’s not enough research for me to able to systematically arrive at an effective dose that I can pass along,” she said. MeV
