McMaster Fecal Egg Counts (FEC) method

The McMaster method is a test to determine worm eggs in the feces of animals. The most common worms are to be determined with this method and provide an indication of the infection. In addition to the count, it is also important to measure the worm resistance.

Testing method McMaster Fecal Egg Count (FEC):

1 Dissolve 500 grams of flotation salt in 700 ml of warm water.
2 Weigh 4 grams of feces off.
3 Add 26 ml flotation salt solution and mix well.
4 Filter the liquid with a tea strainer.
5 Take 2 ml from the top of the liquid with a syringe.
6 Fill both sides of the McMaster counting chamber and place the counting chamber under a microscope.
7 Count the worm eggs in the two grids of the McMaster counting chamber.
8 Multiply the number of eggs found with 25 for the number of Eggs Per Gram (EPG).


Testing method Fecal Egg Count Reduction (FECRT):

Two weeks after deworming do the Mc Master test again. If the reduction is less than 90-95% is the indication of worm resistance.

FECRT calculation: ((EPG pre-treatment – EPG post-treatment) /  EPG pre-treatment) x 100