Hyaluronic acid (HA) is an acidic mucopolysaccharide and included in most body fluids and tissues. In human, a relatively large amount of HA is detected in synovial fluids, umbilical cords, and vitreous body of eye. In these tissues, it influences several different functions including tissue viscosity, tissue osmosis, shock, absorption, wound healing and space filling. The circulating HA is secreted from various tissues including skin, liver, and synovial membrane, and rapidly removed from blood by sinusoidal endothelial cells in liver. In human medicine, serum concentration of HA is clinically applicable as a diagnostic biomarker for some pathologic conditions including cancer, rheumatoid arthritis, and hepatic fibrosis and cirrhosis. On the other hand, clinicopathologic significance of serum HA is still unclear in small animal medicine. The purpose of this study was to demonstrate the serum level of HA in normal dogs and dogs with liver diseases.
In this study, 15 healthy Beagles (control group) and 32 dogs with liver disease [19 congenital portosystemic shunt (CPSS), 6 hepatocellular carcinoma (HCC), and 5 gallbladder mucocele (GM)] were used. Blood samples were collected from the jugular vein, and centrifuged 3,000 rpm for 10 min. The serum was separated and stored at -20°C until the assay. Serum concentration of HA was measured by enzyme-linked immunosorbent assay. In addition, the measurement of serum HA was performed 2 and 4 weeks after the operation in the dogs with CPSS. The serum level of HA was expressed as median (range). The serum level of HA in dogs with liver diseases were statistically analyzed.
The serum levels of HA in control group, CPSS, HCC, and GM were 59.17 ng/ml (31.64-117.36 ng/ml), 308.50 ng/ml (50.55-903.66 ng/ml), 65.39 ng/ml (30.24-106.21 ng/ml), and 49.00 ng/ml (24.48-90.51 ng/ml), respectively. In dogs with CPSS, serum level of HA significantly increased compared with control group. On the other hand, serum levels of HA in dogs with HCC and GM were not significantly elevated compared with control group. In addition, postoperative level of serum HA was significantly reduced compared with the preoperative level in dogs with CPSS.
In canine CPSS, the reduction of intrahepatic portal blood flow by the shunting vessel might induce low clearance rate of HA in hepatic sinusoidal endothelial cells with increase in serum level of HA. In conclusion, serum HA is suggested to be of clinical value for evaluating the attenuation of shunting vessel and improvement of hepatic sinusoidal endothelial function in dogs with CPSS.