Researchers have identified protein differences in the saliva between horses with equine gastric ulcer syndrome (EGUS) and healthy horses. The study also detected differences between equine glandular gastric disease (EGGD), in which there is a lesion in the glandular stomach, and equine squamous gastric disease (ESGD), in which the alteration appears in the non-glandular stomach. This research opens up the possibility of replacing invasive scoping procedures with a simple and easy to administer saliva analysis. The report was published in the journal Animals and you can read the full report here.
The most unregulated proteins in EGGD were related to the immune activation whereas, in horses with ESGD, the proteins with the most significant changes were associated with the squamous cell regulation and growth. Compared to serum, saliva had a higher number of proteins showing significant changes and also showed a different pattern of changes, indicating that the proteins in both fluids show a different response to the disease and can provide complementary information.
As someone whose horse has had ulcers, I know that it is difficult to diagnose them just from physical symptoms. Zelda never lost her appetite, or lost weight, or showed any abdominal distress. Her only symptoms were some grumpiness under saddle and restlessness in the trailer. I had her scoped believing that they would find nothing and was shocked when she had both types of ulcers.
There is only one diagnostic method currently to determine whether your horse has ulcers: scoping. To “scope” a horse for ulcers a vet inserts a video camera up the horse’s nose, through its esophagus and into the stomach so that the vet see whether or not there are lesions. You can read more about it and see photos of Zelda’s stomach here .
There’s a lot of prep for scoping. Your horse cannot eat 12 hours — which is tough when your horse lives outside on a grass paddock! Then there’s the difficulty of getting your vet there. The practice I use has their scopes in constant rotation and a farm visit can take several weeks. Imagine if a saliva test provided the basic results (obviously, a scope gives you a detailed view of the stomach and where the ulcers are located).
Led by Alberto Muñoz-Prieto, the researchers set out to pinpoint salivary proteins using a molecular-based technique that allowed them to identify and quantify the different peptides present. They used the technique to assess the salivary proteome in 12 horses with gastric ulcers. Half the horses had equine glandular gastric disease and the other half had squamous gastric disease. The results were compared to those from 10 healthy control horses. Serum was also analyzed for comparative purposes.
Comparing the results between horses with EGUS and healthy horses, the researchers found significant changes in 10 salivary proteins. In addition, there were 36 differences in the salivary proteins between horses with EGGD and ESGD.
While the findings were significant, the authors emphasized that their work should be considered a pilot study and will require larger-scale validation and the development of high throughput tests to quantify the potential biomarker proteins identified.
The protein differences identified in the study make it clear that glandular gastric disease and squamous gastric disease in horses have two different pathophysiological mechanisms, they said. This suggests they should be considered two different diseases instead of combining them into a single equine gastric ulcer syndrome.
This large-scale validation should include a larger number of horses with gastric disease, as well as horses with other diseases, in order to determine the clinical sensitivity and specificity of these proteins, and to evaluate their possible use as biomarkers for diagnostic or monitoring purposes.
The study team comprised Muñoz-Prieto, Maria Dolores Contreras-Aguilar, Jose Joaquín Cerón, Ignacio Ayala, Maria Martin-Cuervo, Juan Carlos Gonzalez-Sanchez, Stine Jacobsen, Josipa Kuleš, Anđelo Beletić, Ivana Rubić, Vladimir Mrljak, Fernando Tecles and Sanni Hansen, variously affiliated with the University of Zagreb in Croatia, the University of Murcia in Spain, the University of Extremadura, also in Spain, Heidelberg University in Germany, and the University of Copenhagen in Denmark.