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Background/Objectives: Saliva is gaining importance as a diagnostic sample in pigs. The aim of this research was to evaluate a panel of salivary analytes in three porcine diseases and establish predictive models to detect them. Methods: Saliva samples were obtained from healthy pigs (n = 97) and pigs affected by meningitis due to Streptococcus suis (n = 118), diarrhea due to enterotoxigenic Escherichia coli (ETEC, n = 77), and porcine reproductive and respiratory syndrome (PRRS, n = 52). The following biomarkers were analyzed: adenosine deaminase (ADA), haptoglobin (Hp), calprotectin (Calp), aldolase, alpha-amylase (sAA), lactate dehydrogenase (LDH), total protein (TP), and advanced oxidation protein products (AOPPs). Predictive models based on binary logistic regression and decision trees combining those analytes for detecting specific diseases were constructed. Results: The results showed a different biomarker profile between the groups. S. suis and ETEC pigs showed higher values of ADA, Hp, Calp, aldolase, sAA, LDH, and TP than healthy pigs. Pigs with PRRS showed higher values of Hp, Calp, sAA, and LDH than healthy animals. The constructed predictive models showed overall accuracies of over 78% and 87% for differentiating ETEC and PRRS, respectively, whereas the models did not accurately predict S. suis infection. Conclusions: Salivary analytes show different changes in pigs depending on the disease, and the combination of these analytes can contribute to the prediction of different diseases. Further studies should be conducted in larger populations to confirm these findings and evaluate their possible practical applications. [ABSTRACT FROM AUTHOR]

Simple Summary: The use of saliva as a sample for the measurements of biomarkers is growing in pigs due to its easy collection, which does not produce stress in animals. Cystatin C, ammonia, and bicarbonate have been reported to be biomarkers of sepsis and inflammation in humans, but there is a lack of information about assays for the measurement of these analytes in pigs. The objective of this report was to validate commercially available assays for the measurement of Cystatin C, ammonia, and bicarbonate in the saliva of pigs and study the variations of these analytes in a septic disease such as Streptococcus suis (S. suis) infection. The assays showed adequate precision and accuracy for the measurements of the three analytes in the saliva of pigs. In addition, −80 °C was the temperature recommended to store samples for the measurement of these analytes. Pigs with S. suis infection have higher mean concentrations of cystatin and ammonia and lower concentrations of bicarbonate in their saliva than healthy pigs. Based on these results, cystatin C, ammonia, and bicarbonate can be measured in the saliva of pigs and can be potential biomarkers in this species. Cystatin C, ammonia, and bicarbonate have been described to be biomarkers of sepsis and inflammation in humans. The saliva of pigs can be used to detect a wide range of pathogens but also many biomarkers that can be analyzed to evaluate different conditions such as stress (i.e., cortisol and alpha amylase), immune system (i.e., ADA, S100 proteins), inflammation (i.e., acute phase proteins), redox status (i.e., various antioxidants and oxidants), and general metabolism or the status of different organs and tissues. However, there is a lack of assays for the possible measurement and use of cystatin C, ammonia, and bicarbonate in saliva as biomarkers of sepsis or inflammation in pigs. The objective of this study was to validate commercially available automated assays for the measurement of cystatin C, ammonia, and bicarbonate in the saliva of pigs, having the advantage of using a noninvasive sample that is easy to collect. The assays were precise and accurate, and the recommended storage condition for the saliva samples was −80 °C. In addition, cystatin and ammonia showed significant increases in the saliva of pigs with S. suis infection, whereas bicarbonate decreased. Further studies would be recommended to increase knowledge about the possible potential applications of the measurements of these three analytes in the saliva of pigs as biomarkers to evaluate the animals' health and welfare. [ABSTRACT FROM AUTHOR]

Ammonia (NH3) and bicarbonate (HCO3) have been related to gastric ulcers in humans. Ammonia is considered a possible cause of gastric ulcers, whereas bicarbonate has a protective function. The presence of ulcers in the stomach of horses is defined as Equine Gastric Ulcer Syndrome (EGUS), which is a frequent disease in this species, and it has been associated with changes in saliva composition, such as in analytes related to inflammation, immune system and oxidative stress. The objectives of this study were (1) to perform an analytical validation of two automated spectrophotometric assays, one for ammonia and one for bicarbonate, in the horses' saliva and (2) to evaluate their possible variations with EGUS. Analytical validation of the automated assays for ammonia and bicarbonate in the saliva of horses showed that both assays were precise and accurate. In addition, significantly higher values of ammonia and lower values of bicarbonate were found in the saliva of horses with EGUS compared to healthy horses. It can be concluded that ammonia and bicarbonate can be measured in the saliva of horses and that ammonia increases and bicarbonate decreases in this sample type could be related to the presence of EGUS in this species. [ABSTRACT FROM AUTHOR]