Dose titration of moxidectin oral gel against migrating Strongylus vulgaris and Parascaris equorum larvae in pony foals

• Published in: Veterinary parasitology Vol. 60; no. 1; pp. 103 - 110
• Main Authors: Monahan, C.M., Chapman, M.R., Taylor, H.W., French, D.D., Klei, T.R.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01-11-1995
• Subjects: Administration, Topical; Animals; Animals, Newborn; ANTHELMINTHIQUE; ANTHELMINTICS; Anthelmintics - administration & dosage; Anthelmintics - therapeutic use; Anti-Bacterial Agents; ANTIHELMINTICOS; Ascaridida Infections - drug therapy; Ascaridida Infections - veterinary; Ascaridoidea - drug effects; Ascaridoidea - isolation & purification; Ascaridoidea - physiology; CONTROL DE NEMATODOS; Control methods-Nematoda; Dose-Response Relationship, Drug; Equidae; Gels; Horse; Larva; LARVAE; Larval migration; LARVAS; LARVE; LUTTE ANTINEMATODE; Macrolides - administration & dosage; Macrolides - therapeutic use; Moxidectin; NEMATODE CONTROL; PARASCARIS EQUORUM; PONEY; PONIES; Strongylida Infections - drug therapy; Strongylida Infections - veterinary; Strongylus - drug effects; Strongylus - isolation & purification; Strongylus - physiology; STRONGYLUS VULGARIS; Moxidectin; Larval migration; Strongylus vulgaris; Control methods-Nematoda; Horse; Parascaris equorum
• ISSN: 0304-4017; 1873-2550
• DOI: 10.1016/0304-4017(94)00763-3

Moxidectin was tested for efficacy in ponies against experimental infections of 56 day
Strongylus vulgaris larvae and 11 day
Parascaris equorum larvae. Three dosage of moxidectin were tested: 300 μg per kg live body weight, 400 μg per kg, and 500 μg per kg, and the vehicle served as control. Ponies were first infected with 600
S. vulgaris third-stage larvae (L
3) on Experiment Day 0 and then with 3000 embryonated
P. equorum eggs on Day 45. Moxidectin treatments were administered on Day 56 and necropsy examinations were performed on Day 91.
Strongylus vulgaris fourth-stage (L
4) and fifth-stage (L
5) larvae were recovered at necropsy from the control ponies, in dissections of the cranial mesenteric artery and its branches (L
4 and L
5), and recovered from nodules in the wall of the cecum and ventral colon (L
5).
Parascaris equorum larvae were recovered from the small intestine of control ponies. Moxidectin was highly efficacious against
S. vulgaris L
4 and L
5 at all three doses tested (99.6–100%), and appeared to be equally efficacious against
P. equorum larvae (100%); however, control ponies had low levels of
P. equorum infections compared to previous experimental infections performed using identical methods. This suggests that the prior
S. vulgaris infection on Day 0 may have influenced the subsequent experimental
P. equorum infection on Day 45 and contributed to the lower recovery.