Identification of third stage larvae of strongyles and molecular diagnosis of Strongylus vulgaris in the feces of Thoroughbred horses kept in training centers in Rio de Janeiro, Brazil.

The research article discusses a study aimed at identifying strongyles, particularly Strongylus vulgaris, in the feces of Thoroughbred horses in training centers in Rio de Janeiro. The study also compares molecular diagnosis with feces culture methods and examines the association between the presence of S. vulgaris and horse’s age, gender, and anthelmintic use.

Research Objectives

• To identify the strongyles in the feces of Thoroughbred horses based on the morphology of the third stage larvae.
• To detect the presence of Strongylus vulgaris using molecular diagnosis and compare these results with traditional feces culture methods.
• To explore the association between the presence of S. vulgaris and the age, gender, and anthelmintic use of the horses.

Methodology

• The study used feces from horses kept in six different training centers in Rio de Janeiro that showed an egg per gram (EPG) count of over 500.
• From the 520 collected samples, 35 samples had an EPG of more than 500 and were subjected to strongyle identification.
• The researchers conducted fecal cultures for the identification of the third stage larvae, first extracting DNA from the larvae, then subjecting the extracted DNA to Polymerase Chain Reaction (PCR) to amplify the ITS2 region DNA fragment of S. vulgaris.
• Afterwards, the amplified DNA product was sequenced.

Results

• The researchers analyzed a total of 3500 larvae, most of which (99.7%) were classified as small strongyles, with a subfamily of Cyathostominae also commonly found.
• S. vulgaris forms only corresponded to 0.2% of the total larvae analyzed.
• Of all the samples, 25 showed amplified S. vulgaris DNA products and 11 showed nucleotide sequences with high sequence identity.
• The fecal culture and PCR results displayed poor agreement with a Kappa value of 0.105 for the diagnosis of S. vulgaris.
• Age, gender, anthelmintic use, and the interval of anthelmintic administration did not statistically significantly impact the presence of S. vulgaris.

Conclusions

• The study confirmed the presence of S. vulgaris in the feces of horses kept in the Rio de Janeiro training centers, primarily using PCR as a diagnostic tool.
• PCR emerged as the most effective tool for the diagnosis of strongyles, indicating a valuable strategy for future studies on parasite identification.
• The study emphasizes the necessity for the consistent monitoring of horses for the presence of these strongyles, although no statistical relation was established with age, gender, or anthelmintic use of the horses.