Fecal Examinations

Strongyle eggs.

A fecal exam checks a fecal (manure) sample for parasite (worm) eggs.

Annual Fecal Egg Count (FEC)

A yearly FEC is recommended for all horses. It is best done in the spring, when internal parasites are gearing up to contaminate your pasture with the most eggs. It should be done prior to deworming in the spring.


All we need is a fresh manure sample from your horse; 2-3 fecal balls are sufficient. We use the Modified Wisconsin method.  It is a double centrifugation combined with a 2 hour float.  Any parasite eggs present adhere to a glass cover slip and are then counted under the microscope.   While this method takes longer than a simple float it gives a much more reliable fecal egg count (FEC) as 5 times more manure is used than with a simple float method.


The eggs of strongyles are most commonly found in adult horses, while ascarids are more commonly found in young horses.

Tape worm eggs, which pass out of the horse in the tape segments, are hard to find. There is a blood test available that better determines tapeworm infestation.


Ideally, there should be no eggs present. If the sample was taken 14 days after your horse was dewormed, it indicates that the parasites have built up a resistance to the dewormer that was used.