Should ALL horses be dewormed in spring?
Spring is here and the change in seasonal conditions means we need to start thinking about deworming our horses again. Rapidly growing pasture and warm, moist conditions provide an ideal environment for strongyles to start laying eggs. So, does this mean all horses should be dewormed?
It now recognised that 20% of horses carry 80% of the worm burden. Best deworming practice relies on the results of faecal egg counts (FECs) to identify the shedding category of your horse. Basically, you examine the horse’s manure under a microscopic and count how many eggs there are. Horses are considered to be low shedders if there FEC has less than 200 eggs per gram, a moderate shedder with 200-500 eggs per gram, and a high shedder with greater than 500 eggs per gram. Horses that are low shedders have a better natural immunity to worms and therefore don’t need to be dewormed as frequently throughout the year. FECs are pretty inexpensive to do and you can contact your local vet to drop off a manure sample.
Deworming based on FECs will help to combat the emerging resistance problem to deworming drugs (anthelmintics) in Australia. Anthelmintic resistance is the ability of worms within a population to survive a treatment with a drug that is normally effective at killing them. These worms then go on to reproduce and pass on the resistant genes to their offspring, creating a population of worms that is very difficult to get rid of!
Tailored deworming programmes need to be developed for each individual property. Performing FECs will help you to identify whether there is a resistance problem on your farm. It is best to minimise the number of deworming treatments each year, only treat horses with a moderate to high shedding category and implement good pasture management and husbandry practices to reduce the risk of parasite transmission.
How to slow anthelmintic resistance:
- Pick up manure at least twice a week.
- Avoid overcrowding (maintain low stocking densities in paddocks).
- Avoid feeding horses off the ground (e.g. use feed bins).
- Don’t drench in very hot or very cold weather.
- Correctly dose horse according to weight.
- Cross graze with cattle or sheep.
- Quarantine and FEC newcomers on property.
In spring, it is best to use a dewormer such as Kelato’s Revolve, which contains two active ingredients, Morantel Tartrate and Oxfendazole. Morantel acts on the nervous system of the parasites causing paralysis. As a consequence, the parasites are unable to attach to the intestinal wall and are expelled from the gut. The form of Morantel in Revolve is particularly soluble, resulting in a high degree of efficacy. Oxfendazole interferes with the metabolic pathways of adults and sterilises eggs within 24 hours of dosing, thereby reducing pasture contamination.