The long-running co-evolution of small strongyles with horses has derailed the efforts of scientists to infect laboratory animals with the common parasite.
Small strongyles, also known as small redworms or cyathostomins, are one of the most harmful parasites to affect horses.
The parasite has an encysted stage in which they hibernate in the gut lining, generally emerging in spring. A mass release can cause serious gut problems and even death.
More than 50 species of small strongyles have been identified, of which more than 40 have been described in horses. In the individual host, 8–12 common species usually account for most of the parasite burden.
High levels of infection result in clinical symptoms ranging from chronic weight loss to colic, diarrhoea or severe inflammatory intestinal disease.
Štěpánka Scháňková and her colleagues, writing in the journal Scientia Agriculturae Bohemica, said experimental work with horses was extremely difficult for many reasons.
Finding suitable model hosts for equine small strongyles would provide an excellent opportunity to investigate different aspects of the life cycle and biology of this parasite group, the study team from Czech University of Life Sciences said.
The study team, inspired by reports of successful infection of various laboratory animals with related nematodes that infect domestic ruminants, set out to investigate the susceptibility of five laboratory animals to equine cyathostomins.
Their work involved six strains of white laboratory mice, as well as guinea pigs, rabbits, rats, and Mongolian gerbils.
They tried to experimentally infect them by mouth with the infective L3 larval stage.
All attempts to infect them failed, they reported.
“There was no larval development in the experimental rodents and it can be stated that none of the investigated animals may serve as a suitable model host for horse nematodes of the subfamily Cyathostominae,” they wrote.
Their strict host preference for the horse can probably be attributed to their long common evolution together, they said.
Scientia Agriculturae Bohemica is the journal of the Prague-based Czech University of Life Sciences.
Screening of Model Animals for Experimental Infection with Equine Cyathostomes
Š. Scháňková, I. Langrová, I. Jankovská, J. Vadlejch, Z. Čadková, D. Křivská
Animal Sciences, doi: 10.2478/sab-2018-0003