Premier Horse Agistment

Split Rock Mountain

The image above is of worm eggs as seen under a microscope (400X)

Horses have evolved with intestinal parasites and it is normal for horses to carry a low number of worms. Avoiding treating horses with low level infestations means that the these worms are not exposed to chemical wormers. This helps prevent the development of resistance. It also provides a ‘refugia’, a relatively small population of worms occupying the available space in the gut and remaining  sensitive to treatment should it be required.

Adult horses can safely carry up to 200 eggs per gram of faeces. Only horses with counts significantly above this should be treated.  Current research shows that the repeated worming of horses is leading to parasites developing increased resistance to some wormers.  This poses serious risks for the future, as there is no real prospect of new wormers becoming available.

Of course, an additional advantage of using worm egg counts to direct strategic worming is that it is so much cheaper.  Appropriately managed horses rarely require worming.

At Split Rock Mountain, worm egg counts are carried out on site at no cost to owners. Less than 10% of adult horses require worming following testing. This is in part due to the horses grazing in large paddocks, thus lowering the chance of any infective larvae being ingested. Paddocks are also regularly spelled so larvae do not survive. Any horses with a high worm burden, usually new arrivals, are treated and monitored for 10 days, reducing to opportunity for larval transmission.

How a worm egg count is carried out

Two grams of fresh manure are suspended in 50 millilitres of a saturated salt solution. Precisely measured volumes of this suspension, 0.5 millilitres in each case, are introduced into the channels of a glass counting chamber. This counting chamber is then placed under a microscope and examined, at a magnification of 400X, for worm eggs. From the number of eggs observed in each channel of the chamber, the number of eggs per gram of faeces can be calculated.