An ultrasonographic scoring method for transabdominal monitoring of ascarid burdens in foals.
Authors: Nielsen M K, Donoghue E M, Stephens M L, Stowe C J, Donecker J M, Fenger C K
Journal: Equine veterinary journal
Summary
# Editorial Summary Parascaris ascarid infections pose a significant risk to foals, potentially causing life-threatening small intestinal impactions, yet current diagnostic methods cannot quantify worm burden or identify at-risk individuals. Nielsen and colleagues developed and validated a transabdominal ultrasonographic scoring system (rated 1–4) using three locations along the ventral midline, demonstrating reliable detection of burdens exceeding 10 ascarids through dual consecutive examinations with fair to moderate intra- and interobserver agreement (assessed via kappa values). In a randomised treatment trial of 15 foals receiving ivermectin, oxibendazole, or no treatment, ascarid scores declined following both anthelmintic protocols, and the technique proved sensitive and specific for moderate to heavy infections. Cost-benefit analyses revealed the screening approach becomes financially justified when ascarid impaction probability exceeds 0.0001–0.0082 (approximately 1 in 10,000 to 8 in 1,000 foals), making it a practical tool for identifying foals requiring intervention before clinical obstruction develops. For veterinary practitioners and farriers working with foal populations, this ultrasonographic method offers a non-invasive means to monitor parasite burden dynamics post-treatment and inform targeted anthelmintic strategies, though standardised training and consistent technique will be essential for reliable clinical application.
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Practical Takeaways
- •Transabdominal ultrasound can non-invasively estimate ascarid burden magnitude to identify foals at risk of impaction, filling a diagnostic gap for practitioners
- •Two consecutive exams using the standardized 3-location, 4-point scoring system are required for reliable detection of significant worm burdens (>10 worms)
- •Cost-benefit analysis supports selective use of this screening method in populations with higher impaction risk rather than routine screening of all foals
Key Findings
- •Two consecutive transabdominal ultrasound examinations reliably detected ascarid burdens of >10 worms using a 1-4 scoring system at 3 ventral midline locations
- •Ascarid scores declined following both ivermectin and oxibendazole treatment, though differences were not statistically significant
- •Fair to moderate intra- and interobserver agreement was achieved using kappa analysis
- •Ultrasound screening becomes cost-effective when probability of ascarid impaction exceeds 0.0001-0.0082 (1 in 10,000 to 8 in 1,000 foals)