Gastrointestinal parasite occurrence in Slovak horses and factors affecting Strongylidae and Parascaris spp. egg shedding.

Gastrointestinal parasitic infections, particularly strongylids and Parascaris spp., were studied in Slovak horses to determine their prevalence and factors influencing parasite egg shedding.

Study Overview and Objectives

• The research aimed to fill knowledge gaps regarding the prevalence of gastrointestinal helminths in horses in Slovakia, focusing on strongylids and Parascaris spp.
• It also aimed to identify factors that affect the intensity of parasite egg shedding in horses, such as age, breed, management, and parasite control practices.

Methodology

• A total of 392 fecal samples were collected from horses across 24 different farms.
• The McMaster method, with a sensitivity of detecting 50 eggs per gram (EPG), was used to detect nematode eggs, particularly targeting strongylids and Parascaris spp.
• To detect eggs of Anoplocephala spp. (tapeworms), a double-centrifugation combined sedimentation-flotation protocol was applied.
• Data on horse age, breed, farm management conditions, and parasite control approaches were gathered to associate these variables with parasite egg shedding levels.

Key Findings: Prevalence and Intensity of Infection

• Strongylids were detected in 65.6% (257 out of 392) of the horses.
• Strongylid eggs per gram (EPG) counts ranged widely from 50 up to 2800, indicating varying intensities of infection among the horse population.
• The distribution of strongylid egg shedding was highly aggregated, with about 30% of horses producing 80% of the strongylid egg output, highlighting ‘over-dispersed’ infection patterns typical for parasitic infections.
• Parascaris spp. eggs were detected in 4.5% of horses, showing a much lower prevalence compared to strongylids.
• Anoplocephala spp. eggs were very rare, found in only 0.3% of horses, and no other helminth eggs were detected.

Factors Influencing Parasite Egg Shedding

• Multivariate statistical analysis was used to understand how different factors affected parasite shedding:
• Strongylid infections:
  • Horse age was a significant predictor—likely reflecting that young horses typically have less acquired immunity and higher parasite burdens.
  • Stocking density on farms was also significant—higher horse densities likely facilitate parasite transmission, leading to higher infection levels.
• Parascaris spp. infections:
  • Only horse age showed a meaningful effect, consistent with the biology of Parascaris spp., which predominantly infect foals and young horses.
  • No significant influence from management or stocking density was observed for Parascaris spp.

Significance and Implications

• This study provides important updated baseline data on gastrointestinal parasite prevalence in Slovak horses, which was previously limited.
• Recognizing that strongylid egg shedding is heavily influenced by age and stocking density can help optimize pasture management and targeted deworming strategies.
• Identification of a small subset of horses responsible for most egg shedding supports selective treatment approaches (targeted selective treatment) to reduce anthelmintic resistance development.
• The low prevalence of Parascaris spp. and Anoplocephala spp. suggests they are less of a concern overall but warrant monitoring, especially in younger horses for Parascaris spp.
• Overall, these findings can assist veterinarians and horse managers in Slovakia to implement more effective parasite control programs that consider horse age and farm management practices.