Performing a coprological examination after an antiparasitic treatment

Solution name: Performing a coprological examination after an antiparasitic treatment

Aim: to detect gastrointestinal strongyles resistant to pest control treatments on farms

As resistance (and multiple resistance) of gastrointestinal strongyles to treatments continues to increase, it becomes essential to detect as soon as possible potential resistance to frequently used parasites control molecules in sheep farms.


  • Day 0: two groups of 10 animals are identified within the same batch (ewe lambs, young sheep, ewes) The first group will act as a control group. These animals won’t be given any treatment. The second group will be given a treatment based on the molecule to be tested and depending on the manufacturer’s recommended dosage.
  • The weight of the group’s heaviest animal defines the quantity of treatment to be given to the others. For this experiment, the goal is to give the proper amount of pest control treatment to each animal.
  • 14 days post-treatment (day 14): both groups’ faeces are collected directly from the animals’ rectum and individually conditioned/identified in small plastic bags. .
  • Faeces are then to be sent refrigerated (ideally at 4°C) to the laboratory. The samples should never be frozen. A pooled sampled coprological examination is then conducted for both groups at the lab.
  • This analysis should be carried out according to the following protocol:  One gram of faeces is collected on each individual and placed in individual plastic bags. 10 samples per group are then mixed. The method chosen for this experiment is the flotation using sodium chloride (density 1.2) and McMaster slides. The intensity at which eggs are excreted is expressed in eggs per gram (EPG) of faeces.

Results interpretation:

  • A reduction in the intensity of egg excretion in faeces is subsequently calculated using the following formula:

    % of reduction = ((1 – (treated group’s EPG/control group EPG) x 100)

    If the percentage of reduction exceeds 95%, the tested anthelmintic molecule is considered efficient. If this percentage goes below 95%, resistance is suspected. The closer this percentage is to 0%, the stronger the suspicion.

Topic: Health

Production:  Dairy / Meat

Animal Category: Adult / Lamb / Replacement

Issue: Internal parasitism (e.g. Liver Fluke, Gastrointestinal,  Haemonchus, Coccidiosis, Cryptosporidiosis, worms, etc.), Anthelmintic management (e.g. faecal egg count, anthelmintic resistance, grazing management)

Level of Solution: Practical

Country: France







copro prelevement
Expected benefits

How to implement it:
Equipment: single use gloves, plastic bags/jars, a treatment containing the active substance whose efficiency is to be tested

 Expected benefits:

  • Knowing how efficient a pest control molecule will be on a farm.
  • Enables the farmer to adapt his pest control strategy by reasonably using a molecule proved to be efficient, or by changing the chemical family if the first one proved to be inefficient.

NB: Control of gastrointestinal strongyles should be combined with various pest control methods, and not rely on the sole use of pest control molecules.

 Prerequisites and/or limits:
– Requires a lab or vet
– As the results can drastically differ from one farm to another, each farm needs to perform these analyses, no matter how close the farms are to each other
– Respect deadlines: efficiency control must be carried out on the 13th, 14th or 15th (at the latest) day post-treatment.
– Cost: 12-15€/analysis (per group). A lab will charge 30€, but the amount of time dedicated to the protocol’s implementation must also be considered, including the cost of small equipment items (plastic bags, etc.) and the treatments tested.