at the correct dose and administered, it will not be effective. Fecal Egg Counts can be very useful to identify resistance to dewormers. See Fecal Egg Count Reduction test below.
Compound Microscope (at 10x magnification)
McMaster Fecal Egg Count Slide
Gram scale
3-4 inch tea strainer
Fecasol solution (or similar solution)
30 mL syringe
Pipettes or 3 mL syringe
3 oz wax cups
Stirring sticks
Collect a sample of feces. The sample should be fresh or less than 24 hours if kept in a refrigerator. (If doing multiple samples, don't forget to label bag or glove with a sharpie.)
Using gram scale, measure the gram scale and wax cup. Place the cup on the scale, then push the zero or tare button to make sure you are counting the weight of the cup. Measure out 2 g of feces. (For adults, 2 g is about 2 pellets; young animals may be 4-6 pellets.)
With a large syringe, add 28 mL of fecal solution to the feces in the cup and mix thoroughly with stir stick until pellet is dissolved. Small pieces of debris may still be present.
Pour the solution through the tea strainer into a clean wax cup to remove large particles from feces.
Use a pipette or small syringe to carefully fill both chambers of the McMaster's slide. Slowly pull up fluid from the cup and completely fill chamber, avoiding air bubbles within the area of the grid. To avoid air bubbles in the chamber, hold slide horizontally and place tip of pipette or syringe in one corner and slowly fill.
Let the McMaster's slide sit for 5 minutes to allow eggs to float to the top.
Place slide on the microscope stage and focus at 10x magnification until the gridlines are clear.
8. Count number of parasite (HOT) eggs within each grid. Use the gridlines to systematically move through the slide, up one column and down the next, until the entire grid is counted. Do not count eggs outside of gridlines.
Count number of parasite (HOT) eggs within each grid. Use the gridlines to systematically move through the slide, up one column and down the next, until the entire grid is counted. Do not count eggs outside of gridlines.
Add the total number of eggs from each chamber and multiply by 50 to get number of eggs per gram of feces.
Fecal Egg Count Reduction Tests are used to determine the effectiveness of dewormers. Resistance to dewormers in small ruminants may develop on multiple types of dewormers, and dewormer effectiveness may vary from farm to farm. Because of this, a specific dewormer may be effective for a herd/flock and not be effective for a farm next door. Some of the causes for loss of effectiveness are overuse of a product, repeated use of a product and improper dosing or administering of product. For these reasons, it is important to monitor for resistance in your herd to make sure that the product is being effective and, if not, finding a product that is effective.
For this test, an initial Fecal Egg Count (FEC) is determined; the animal is then given a dewormer and, after a certain amount of time (preferably 10-14 days post deworming), another FEC is done to see how much the FEC was reduced by giving the dewormer. To determine the effectiveness of a drug for an entire herd/flock, multiple animals should be tested based on the size of the herd/flock. In some situations, an individual animal may have a weakened immune