Page 95 - September 2023

is true. Strongyle transmission occurs mostly from September into May. Summers are typically too hot and too dry to support much transmission so there is less need to
deworm during the off-season. A positive fecal exam doesn’t
necessarily suggest a
negative consequence.
For example, if
strongyle eggs are
deposited in a snow drift
or onto a patch of dirt at 98
degrees Fahrenheit, those eggs
aren’t going to survive to be perpetuated. Mother Nature
takes care of transmission during
the off season so in many cases an owner can hold off using anthelmintic drugs until the infective season comes round again.
ENVIRONMENTAL STRATEGIES
Any management strategy that reduces
the environmental presence of infective parasites is one that reduces the frequency of administering anthelmintics to which resistance can build. Cleaning up manure once or twice
a week is an effective method of controlling parasitic infection: This practice effectively reduces the need for anthelmintic treatments, which should delay development of resistance. How often it needs to be done depends on climatic conditions – in cooler climates, once a week may be sufficient whereas at least twice a week is best for warmer climates. Composting is important to kill off infective larvae before fertilizing pastures with manure.
Another potential anti-parasite strategy is the use of predacious nematophagous fungi (Duddingtonia flagrans by Bioverm®). These are fed to the horse as fungal spores, which then pass through the gastrointestinal tract
to end up in the fecal pile with the parasite eggs. The fungi then sporulate, and as parasite eggs are hatching, the fungi trap the larvae
in meshes of budding hyphae (branching filaments) that then kill parasite larvae. The fungal spores have to be fed daily to the horses. As yet, there is no commercial product launched in the USA (only Brazil), but this could provide an effective adjunctive anti- parasite control measure in future.
"With no new drugs on the horizon to use for horse deworming, it is important to be circumspect and educated in using those products that are currently available."
VETERINARY VIEWS
Cleaning up manure once or twice a week is an effective method of controlling parasitic infection.
TAKE HOME MESSAGE
The basic problem is that horse owners keep doing things the same way long after the reason has been forgotten. It’s time to dispense with the old concepts of how to deworm horses and instead use a targeted deworming protocol – selective deworming.
The use of selective deworming practices in adult horses has been shown to be a practical approach to controlling parasite loads in individuals and on farms. Selective deworming is a matter of identifying the active parasite transmission season, and then focusing on anthelmintic treatments – what is used and how often differs between geographic and climatic regions. Have your vet run twice yearly fecal egg counts (FEC) and a yearly fecal egg count reduction test (FECRT) regardless
of the anti-parasitic drug used. This evaluates the efficacy of specific deworming products and also determines which horses need frequent deworming and which need a less rigorous treatment schedule.
With no new drugs on the horizon to use for horse deworming, it is important to be circumspect and educated in using those products that are currently available.
SPEEDHORSE September 2023 93