| With the rapid development of domestic horse industry,the number of equestrian clubs has increased dramatically,and horse foot diseases especially laminitis has attracted wide attention.Laminitis is a common and serve disease that result from pathological changes and inflammation of the hoof lamella,and characterized as diffusive,aseptic,serous and non-suppurative inflammation.Laminitis is the most common disease in the motor system diseases and causes serious harm to horses.It not only brings great economic losses to the horse industry,but also serious harms to animal welfare.But,the pathologic mechanism still not fully understood.It is generally believed that the microcirculation disorder of the hoof caused by the accumulation of harmful substances such as histamine,lactate and endotoxin(LPS)into blood is an important factor in the occurrence of laminitis.The gut is the main location for bacteria colonization in horse.It can provide nutrients for the normal life activities of the host by fermentation of fermentation food.When the stress factors such as sudden change of diet and environment stimulate the intestinal flora to disorder,a large number of harmful substances will be produced,and get into the blood circulation via the intestinal wall,and lead metabolic diseases.Thus,we believe that the occurrence of laminitis may be closely related to the harmful metabolites caused by intestinal flora dysbiosis entering the hoof through blood circulation,which leads to the blood microcirculation disorder in the hoof.Therefore,in this study,firstly,the animal model of laminitis was induced by oral administration of oligofructose;secondly,the levels of histamine,lactic acid and LPS in the blood of horses were detected;finally,16 S r RNA amplification sequencing and non-targeted metabolomics technology were used to detect the intestinal flora and their metabolites,so as to provide theoretical basis and reference methods of equine laminitis.First,after 24 hours of oligofructose administration,the equine laminitis was evaluated by Obel lameness classification system;the blood flow changes of hoof were detected by Doppler ultrasonographic measurement,and the temperature,respiration and heart rate were detected to evaluate whether the laminitis model was successful.We used oligofructose to induce laminitis model in horses,and observed the clinical characteristics of the laminitis according to Obel lameness classification system and clinical symptoms.The results showed that oligofructose can induce laminitis in horses and lead to oblivious clinical symptoms.The doppler ultrasonographic measurement showed that the blood flow of the hoof of laminitis horse was decreased.The histological examination of the hoof showed that the lamella of the laminitis horse was damaged obliviously and lost structural integrity compared with the healthy horses.Second,the serum levels of lactate,histamine and LPS in the blood of the horse induced by oligofructose were detected by ELISA.The results showed that the concentration of lactate,histamine and LPS in the serum of the horses with laminitis were significantly higher than that of healthy horses.Then,the gut microbiota of healthy and laminitis horses was detected by 16 S r RNA amplification sequence technique.The results showed that the relative abundance and diversity of hindgut microbiota in the laminitis horses were significantly reduced compared with the healthy horses.At the phylum level,the relative abundance of Kiritimatiellaeota,Fibrobacteres,Tenericutes,Lentisphaerae,Elusimicrobia,Verrucomicrobia,and Planctomycetes were significantly reduced in the intestinal microbiota in the laminitis horses compared with those of the healthy horses.At the genus level,the relative abundance of Lactobacillus,Megasphaera,and Allisonella were significantly increased,while the relative abundance of Fibrobacter,Phascolarctobacterium,Papillibacter,Alloprevotella,Candidatus＿Soleaferrea,Oribactrium,Akkermansia,and Elusimicrobium were reduced in intestinal microbiota from laminitis when compared to those fromhealthy horses.Finally,the metabolome results indicated that administration of oligofructose reduced 84 metabolites,and 53 metabolites were increased,such as dihydrothymine,N3,N4-Dimethyl-L-arginine,10 E,12Z-Octadecadienoic acid,and asparagine.Pathway analysis revealed that aldosterone synthesis and secretion,regulation of lipolysis in adipocytes,steroid hormone biosynthesis,pyrimidine metabolism,biosynthesis of unsaturated fatty acids,and galactose metabolism were significantly different between the two groups.In addition,correlation analysis between the gut microbiome and metabolites indicated that Lactobacillus and/or Megasphaera were positively associated with thedihydrothymine,N3,N4-Dimethyl-L-arginine,10 E,12ZOctadecadienoic acid,and asparagine.In summary,the findings showed that oligofructose treatment changed the pattern of hindgut normal microbiota and metabolites,showed by increased relative abundance of the Lactobacillus.Megasphaera and levels of lactic acid,histamine,LPS,10 E,12Z-Octadecadienoic acid,asparagine,dihydrothymine,and N3,N4-Dimethyl-Larginine,which may be associated with the damage of laminar tissues of horses.Hence,targeting intestine microbiota and its metabolites may be an important target for preventing equine laminitis. |
