Relationships between Body Condition Score and Plasma Inflammatory Cytokines, Insulin, and Lipids in a Mixed Population of Light‐Breed Horses

Abstract

Background: Obesity and hyperinsulinemia increase the risk of laminitis in horses and ponies. In mares, obesity also has been associated with increased circulating concentrations of the proinflammatory cytokine, tumor necrosis factor (TNF)-a. The association of other proinflammatory cytokines with body condition score (BCS) and insulin requires further determination.Hypothesis: Plasma concentrations of TNF, interleukin (IL)-1b, IL-6, and serum amyloid A (SAA) will positively correlate with BCS or insulin or both in horses. Furthermore, inflammatory protein concentrations will correlate with age and variables associated with BCS, including plasma insulin, triglycerides, nonesterified fatty acids, and leptin concentrations.Animals: One hundred and ten mixed light-breed horses, including mares, geldings, and stallions, aged 4-20 years. Methods: Samples were selected from a larger population of plasma samples previously collected during June-July of 2006. Samples were analyzed for TNF, IL-1b, IL-6, and SAA using commercially available ELISAs and simple correlations were used to determine relationships with BCS, insulin, age, and sex.Results: Plasma TNF (P = .047) and IL-6 (P = .021) concentrations were higher in females than males, whereas IL-6 concentrations correlated (P = .001) with age. Plasma SAA concentrations correlated with both insulin (P < .001) and BCS (P = .007).Conclusions and Clinical Importance: This study provides evidence for factors, including age and sex, that may be associated with plasma concentrations of inflammatory proteins. Concentrations of SAA correlated with BCS and insulin, independent of age or sex. Because BCS and insulin correlate with increased SAA, it is possible that SAA is a component of laminitis pathophysiology.

Pituitary Lesions, Obesity, and Mesenteric Lipomas in Insulin-Resistant Horses

“…Although adrenal cortical hyperplasia is commonly associated with proliferative pituitary lesions in other species, it is uncommon in horses [10] [17]. Likewise, there was no association between pituitary score and adrenal corticomedullary ratio in the current study.…”

“…In humans, obesity has also been associated with increased oxidative stress and inflammation [9]. Similarly, in horses, increased levels of the acute phase protein serum amyloid A (SAA), which are indicative of systemic inflammation and oxidative stress, have been associated with both obesity and IR [10]. However, it is unclear if the increased SAA is a cause or effects of the obesity and IR.…”

“…An IV bolus of 50% dextrose solution (Vedco, Inc.) was then administered at a dosage of 150 mg/kg body weight. Blood glucose and insulin concentrations were measured at 1, 2,3,4,5,6,7,8,10,12,14,16, and 19 minutes after dextrose infusion. A bolus of regular insulin (Humulin R, Eli Lilly and Co.; 30 mU/kg body weight) was administered IV at 20 minutes.…”

Influences of age and sex on leukocytes of healthy horses and their ex vivo cytokine release

“…This may indicate a trend of more pro-inflammatory and less regulatory cytokines in females. This is still a controversial issue in horses (Hamza et al, 2008;Uner et al, 2013;Wray et al, 2013), but is in line with higher plasma levels of TNF␣ found in mares than in geldings of mixed breeds and ages (Suagee et al, 2013).…”

Changes in plasma leptin concentration during different types of exercises performed by horses

“…Moreover, the possible influence of TG and glycerol on plasma leptin release from the adipose tissue is unknown and the role of FFA in the regulation of the leptin level is not clear (Cammisotto et al, 2003). In other studies, the reported connections between plasma leptin and lipid concentrations are more likely to be the effect of the existing energy status of the examined horses (Frank et al, 2006;Pleasant et al, 2013;Suagee et al, 2013).…”