Small strongyles are capable of developing on moist straw bedding and may then be able to infect horses, research suggests.
Researchers from Scotland’s University of Glasgow and Denmark’s University of Copenhagen set out to determine whether horses could become infected by cyathostomins, also known as small strongyles, when bedded in litter straw.
In order to do so, the cyathostomin eggs would have to hatch and develop to the infective larval stages in the bedding.
Eoghan McGirr and his colleagues set up four horticultural incubators to simulate three straw-bedding scenarios and one grass turf control. The straw-bedding variations were dry straw, watered straw, and deep litter straw.
Horse dung was placed on 12 plots, and larval recoveries were performed on samples of straw/grass over a 17-day period.
One plot within each incubator contained a faecal pat from a horse that had tested negative for strongyle eggs to serve as a negative control. Plots 2 and 3 in each incubator contained a faecal pat from horses that had average faecal worm egg counts of 269 eggs per gram and 921 eggs per gram, respectively.
A thermostat within each incubator was set to maintain a temperature of about 20°C.
The study team, in a research presentation to delegates at the recent British Equine Veterinary Association (BEVA) Congress, reported that no infective third-stage larvae were recovered from the control plots in each incubator, and none was recovered from any of the plots within the incubator with the dry straw.
However, third-stage larvae were first detected on plots 2 and 3 of the watered-straw incubator B on day 8, and on plot 3 of both the watered-straw incubator and the deep-litter-straw incubator on Day 10.
It was evident, they said, that equine cyathostomins can develop to the infective L3 larval stage on straw bedding, but only when the straw was moist.
“Therefore, it may be speculated that a horse bedded in deep litter straw may become infected by ingesting the infective L3 larvae contaminating the straw,” they said.
Small strongyles are the most numerous parasite in horses.
A summary of the researchers’ work has been published in the Equine Veterinary Journal as part of the proceedings from the BEVA Congress.
McGirr, E.C., Denwood, M.J., McGoldrick, J. and Love, S. (2015), Equine Cyathostominae Can Develop to Infective Third Stage Larvae on Straw Bedding. Equine Veterinary Journal, 47: 9–10. doi: 10.1111/evj.12486_20
The abstract can be read here.