# Gastrointestinal Nematode Control in Lithuanian Sheep Farms: Insights from a Questionnaire Survey

## TL;DR

This study examines parasite control practices on Lithuanian sheep farms and finds that routine, non-strategic use of deworming drugs is common, increasing the risk of drug resistance.

## Contribution

The study provides insights into anthelmintic resistance risk factors and control practices specific to Lithuanian sheep farming.

## Key findings

- Most farmers use anthelmintics twice a year without diagnostic guidance, increasing resistance risk.
- Organic farms are more likely to use diagnostic testing than traditional farms.
- Many farmers use inaccurate weight estimation for dosing, potentially leading to underdosing.

## Abstract

Gastrointestinal parasite infections are a major challenge in sheep farming, affecting animal health, welfare, and farm productivity. Anthelmintic drugs, commonly used to control these parasites, can become less effective when used too frequently or without proper diagnostic guidance, leading to the development of resistance. This study assessed parasite control practices on Lithuanian sheep farms and explored factors that may promote resistance. A survey of 71 farmers showed that most used anthelmintics routinely, mainly twice per year, but only a small proportion based treatment decisions on diagnostic testing. Organic farms were more likely to use diagnostic methods than traditional farms. Many farmers relied on the visual estimation of sheep weight rather than accurate weighing when determining dosages, increasing the risk of underdosing. Macrocyclic lactones were the most commonly used type of anthelmintic. Quarantine measures for newly introduced animals were not consistently applied. These findings highlight a heavy reliance on routine, non-strategic treatments, and limited use of evidence-based approaches. Strengthening farmer education on parasite management, promoting regular diagnostic testing, accurate dosing, and effective quarantine procedures are essential steps to slow the development of anthelmintic resistance and to support sustainable sheep farming practices.

Anthelmintic resistance (AR) in gastrointestinal nematodes is a growing global concern that threatens effective parasite control in livestock farming. This study aimed to assess gastrointestinal nematode (GIN) control practices and identify risk factors associated with AR development on Lithuanian sheep farms. A cross-sectional survey was conducted between 2022 and 2023 among 71 members of the Lithuanian Sheep Breeders Association, covering farm management, grazing, and deworming practices. Anthelmintics were used by 90.2% of farmers, with most treating their flocks twice a year. Only 18.3% of farmers performed parasitological testing to guide treatments, with significantly more organic farms applying this approach than traditional farms. Treatment frequencies were significantly higher in traditional farms. Most farmers (45.1%) relied on the visual appraisal of sheep weight for dosing, while 35.2% dosed according to the weight of a medium-sized animal. Macrocyclic lactones were the most commonly used anthelmintics (50.7%). Quarantine procedures for new animals were implemented by less than half of the farmers (44.4%), while others treated without isolation (56.6%). These findings indicate reliance on non-strategic parasite control methods and limited use of diagnostics, highlighting the need for improved farmer education to promote sustainable parasite control and reduce AR risk in Lithuanian sheep farms.