Saliva’s potential as a diagnostic fluid explored in horses


Blood tests have been a crucial diagnostic tool for horse vets for decades, but what if similar tests could be performed on saliva?

Saliva is up to 99% water by total volume. However, studies on humans and animals have shown it also contains compounds such as phosphorus, lactate, cholesterol, fatty acids, and glucose, and hormones such as cortisol, triglycerides, urea and uric acid. It also harbors a range of enzymes.

The composition of saliva can be affected by certain health problems, which has driven interest in recent years in the use of saliva as a diagnostic fluid.

For example, one study in horses detected changes in inflammatory-related proteins in the saliva of horses affected by lameness.

María Dolores Contreras-Aguilar and her colleagues, writing in the journal BMC Veterinary Research, noted that saliva has several advantages over blood. In particular, it is easily collected in a non-invasive way and could be done so by horse owners with a minimum of material.

The researchers carried out a study in Spain as a first step to determine whether analysis of saliva could be of potential use in diagnosing health problems in horses.

They set out to evaluate if a panel of biochemical analytes usually assessed in serum could be measured in saliva and if there were any possible changes related to acute abdominal disease.

A panel of 23 analytes was analytically validated in the saliva of horses.

In a pilot study, test results between six healthy horses and six horses with acute abdominal disease were compared.

Seven analytes showed significant increases in the horses with gut problems – a result later confirmed in a larger population of 20 healthy and 37 diseased horses.

The study team confirmed that a panel of 23 biochemical analytes can be measured in the saliva of horses, with γ-glutamyl transferase, creatine kinase, urea, total bilirubin, total proteins, phosphorus and alpha-amylase significantly elevated in horses with acute gut problems.

The increases ranged between 2.3 times and 8.5 times higher than in the healthy controls.

It would be interesting, they said, to carry out future studies in a larger population to see if the changes in the analytes could be related to the chances of survival and the type of abdominal problem.

Further studies should be carried out to evaluate and refine the possible application of saliva tests in clinical situations, they said.

The full study team comprised Contreras-Aguilar, Damián Escribano, Silvia Martínez-Subiela, Fernando Tecles and Jose Joaquín Cerón, all with the University of Murcia in Spain; María Martín-Cuervo, with the University of Extremadura in Spain; and Elsa Lamy, with the University of Évora in Portugal.

Changes in saliva analytes in equine acute abdominal disease: a sialochemistry approach
María Dolores Contreras-Aguilar, Damián Escribano, Silvia Martínez-Subiela, María Martín-Cuervo, Elsa Lamy, Fernando Tecles and Jose Joaquín Cerón.
BMC Veterinary Research 2019 15:187

The study, published under a Creative Commons License, can be read here.

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