Background: Effective control of internal parasites is vital to sheep farming, as parasitic infections lead to substantial economic losses due to decreased weight gain, increased mortality, and compromised nutrient absorption. Targeted Selective Treatment (TST) has emerged as a strategy to optimize parasite control while mitigating drug resistance. Methods: A comparative field study was conducted on a 20,000-head semi-industrial Afshari sheep farm in the Jalgheh Rokh–Torbat Heydarieh region. The efficacy and cost-effectiveness of TST were assessed against blanket (whole-flock) treatment. TST implementation relied on the Five Point Check (FPC) system and parasitological indicators, particularly fecal egg counts (EPG), to identify individuals requiring treatment. Results: Using TST, only 10–15% of the flock received anthelmintic intervention, resulting in an 85–90% reduction in drug use. Parasite burden, as measured by EPG, remained statistically comparable between TST and blanket treatment groups. Economic analysis demonstrated significant cost savings without compromising parasite control. Conclusion: TST represents a sustainable and economically viable alternative to blanket deworming in Afshari sheep. Its implementation minimizes drug usage and delays anthelmintic resistance development, while maintaining effective parasite suppression.

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