Saliva samples may one day replace blood tests as a means of detecting inflammation in horses, according to a new study from the University of Copenhagen.
Building on a process previously used successfully to measure proteins associated with stress, the Danish researchers tried a new and innovative testing technique to detect proteins in saliva that are associated with inflammation.
“The biomarkers we were interested in---so-called acute phase proteins---indicate the presence of inflammation, which occurs whenever the horse has an infection or neoplasia0 or sustains a trauma,” explains Stine Jacobsen, DVM, PhD.
For the study, 13 horses of various breeds and ages were given full physical exams and had their blood tested for acute-phase proteins. Then, based on the blood test results, the horses were divided into two groups---those with inflammation and those without.
Next, the researchers collected saliva samples from each horse and used liquid chromatography tandem mass spectrometry (LC-MS/MS) to search for signs of inflammation. “LC-MS/MS works by breaking down proteins in smaller ‘bits,’ so-called peptides,” says Jacobsen. “These peptides are detected by the machine, and the results are analyzed against a big database, which gives us information about all the proteins present in the sample. The technique is very sensitive, so proteins that are present only in very small quantities are detected.”
Although saliva tests can be helpful, they would be only one step in the diagnostic process, says Jacobsen. “Similar to a blood sample, a saliva sample will show the ‘sum’ of inflammation,” she says. “So if a horse suffers from arthritis and pneumonia, the blood or saliva sample will tell us that there is inflammation but not differentiate the reasons for the inflammation.”
Nonetheless, she says, saliva testing could theoretically replace blood tests now used to detect inflammation in the future. “Obtaining blood is an invasive procedure, while obtaining saliva is not, thus increasing the comfort of the horse. Detection of inflammation through blood analyses of acute-phase proteins and white blood cells are routine in equine medicine today, and potentially saliva may be used for a similar purpose in the future.”
Reference: “The use of liquid chromatography tandem mass spectrometry to detect proteins in saliva from horses with and without systemic inflammation,” The Veterinary Journal, December 2014
This article first appeared in EQUUS issue #454, July 2015.