He was dewormed with QuestPlus 16 weeks ago. Did a FEC 12 weeks later with 175 count strongyles. 4 weeks later this past Friday, the sample was taken from a fresh pile in his stall and taken directly to the vet. It was still warm when they got it.
Got the call this morning that the count was zero.
Boyle Heights Kid 1998 16.2h OTTB Dark Bay Gelding
Tinner's Way x Sculpture by Hail to Reason "Once you go off track, you never go back!"
That's actually not as big of a difference as you might think, given that the fecal sample used is generally quite small, and then the number of eggs found is multiplied to estimate the parasite load in a larger quantity of feces.
Feed can also effect EPG counts. Horses on high quality pastures tend to utilize more of the plant....and pass less stool. At the other end of the spectrum horses eating a lot of lower quality hay are passing more poo with less digestable feeds.
So if 4 wks ago your horse was eating good pasture (but like mine pasture is all but running out) and now getting more hay. Then the hay easily can be diluting the EPG counts respective to the last count and producing your zero count.