Saliva Sampling Material Matters : Effects on the Results of Saliva Analysis in Pigs

There is an increasing interest in measuring biomarkers from saliva, as samples can be obtained noninvasively. This is particularly true in pigs where blood sampling is technically complicated and stressful. In pigs, studies regarding how the absorbent material used for collection affects analytical results are scarce. The aim of this study was to evaluate how the material used for saliva collection can affect the results of analyses for the different types of biomarkers that can be measured in the saliva of pigs. In this report, polypropylene sponges gave higher sample saliva volumes and, in some salivary analytes, provided different values compared with cotton rolls. Therefore, it can be concluded that the type of material used can influence the results of saliva analysis. The use of saliva as a biological sample from pigs is of high practical interest because blood collection from pigs is difficult and stressful. In this study, the influence of two different materials, a cotton roll and a polypropylene sponge, in porcine saliva collection was evaluated. For this purpose, the effect of the material used for sampling was evaluated in a panel of 13 analytes, including those related to stress (cortisol and oxytocin), inflammation and immunity (adenosine deaminase, haptoglobin and myeloperoxidase), redox homeostasis (the cupric reducing ability of saliva, the ferric reducing activity of saliva, and the Trolox equivalent antioxidant capacity), and sepsis (procalcitonin), as well as other routine analytes related to metabolism and different tissues and organs, such as lactate dehydrogenase, creatine kinase, urea, and total protein concentration. The polypropylene sponge provided a higher sample volume than the cotton roll. Although the results of some salivary analytes were equivalent for both materials, other analytes, such as creatine kinase, haptoglobin and total proteins, showed significant differences depending on the material used for saliva collection. Therefore, the type of material used for salivary collection in pigs should be considered when interpreting the results of analyses of the salivary analytes.