The strategic control of equine gastrointestinal nematodes is based on epidemiology. The aim is the reduction of the population of parasites as a whole in the hosts and environment while seeking the number of treatments that achieves the balance between not risking animal health and not exerting selection pressure for resistant parasites. This is the first study in a tropical region to assess a strategic control protocol for equines. The study was conducted in the municipality of Anastácio in the state of Mata Gross do Sul, Brazil, over a two-year period from April 2021 to March 2023, involving two groups of horses - control and treated. The animals in the treated group received oral ivermectin in the months of May and September in each year of the experiment. Every 28 days, feces were collected, the animals were weighed, the body condition score was calculated, eggs per gram (EPG) of feces were counted, and larval counts were performed in the pasture. Eggs were analyzed using real-time polymerase chain reaction for the identification of the species Strongylus vulgaris. Treatment reduced the EPG count (p <
0.05) and did not affect the weight or body condition score of the animals. The most prevalent taxon was Cyathostominae. Treatment was a protection factor against S. vulgaris (p <
0.05). A significant difference was found in the dry season between the control and treated groups in the analysis of larvae in the pasture. In conclusion, strategic control with two treatments during the year was capable of reducing the egg count, number of larvae in the pasture, and the presence of S. vulgaris without affecting health indicators, such as weight and body condition score.