Skip to content

Applying tapeworm testing to reduce anthelmintic treatment frequency in horses

Horses at Bransby

Case Study from Published Article: Lightbody, K.L., Matthews, J.B., Kemp-Symonds, J.G., Lambert, P.A., Austin, C.J., 2018. Use of a saliva-based diagnostic test to identify tapeworm infection in horses in the UK. Equine Vet J. 50;213-219.

A study published in the Equine Veterinary Journal in 2018 (Lightbody et al. 2018) demonstrated how a diagnostic-led approach for equine tapeworm infection led to substantial reductions in anthelmintic usage in horses when compared to an all-group treatment strategy.

Background  

Studies in the UK and Ireland that assessed worm infections within horses have shown that the equine tapeworm, Anoplocephala  perfoliata, has a prevalence of 51-69% (Owen et al. 1998; Fogarty et al. 1994; Pittaway et al. 2014; Lightbody et al. 2016). This tapeworm has previously been shown to be associated with various types of colic (Proudman and Edwards, 1993; Proudman et al. 2008) and that the level of tapeworm burden relates to the level of pathology observed in individuals (Pavone et al. 2010). It is therefore important to target horses with appropriate anti-tapeworm anthelmintics (wormers) to reduce the risk of disease occurring.

Not all horses harbour tapeworm burdens at a level that causes disease and, as frequent all-group administration of anthelmintics can promote drug resistance, it is important to find a balance between controlling pathogenic burdens and applying these medicines. This is particularly important now that potential anthelmintic resistance has been reported in A. perfoliata (Nielsen et al. 2023).  

Targeted approaches, where treatments are applied based on the results of diagnostic tests, provide a solution to controlling tapeworm infections without over-using anthelmintics. This study took a targeted treatment approach in a population of horses based at the equine charity, Bransby Horses (Home – Bransby Horses). As faecal egg count analysis has poor sensitivity for detecting A. perfoliata infections, a saliva test, shown previously to accurately diagnose tapeworm infection (Lightbody et al. 2016), was used to assess which horses carried burdens that required targeting with anti-cestode anthelmintics.  

Study 

Saliva was collected from 237 horses at Bransby from autumn 2015 until autumn 2016. Samples  were  predominantly  obtained  in  October/November  2015 (n=305), April/May 2016 (n=328) and August/September 2016 (n=367) and collected from horses of both sexes and of various breeds and age > 1 years-old. The horses were kept on paddocks on which the level of dung removal varied and were only stabled in exceptional circumstances. Horses diagnosed as positive for tapeworm infection using the EquiSal® Tapeworm test were treated with a praziquantel based anthelmintic product according to their weight. The number of horses that received treatment based on the test result was compared with an all-group treatment approach and the reduction in anthelmintic usage calculated.

EquiSal treatment recommendations based on an individual’s saliva score classified within low, borderline and moderate/high categories.

Results 

Based on the saliva test outcome, in 2015, 85% of the 237 horses assessed received no anthelmintic. Of the horses that tested as negative at the first sampling, 71% remained below the treatment threshold until the end of the study 12 months later. Of 69 horses that were test-positive and received treatment at the first sampling, seven required treatment following three subsequent tests. Over 50% of horses administered with anthelmintic fell below the treatment threshold at the following test. A higher proportion of younger horses 1-5 years-old (21/38) required treatment after testing. Of the horses that were negative and not treated in autumn 2015, 7% required treatment when tested the following spring, and 11% of those that were negative and not treated in spring 2016, tested positive 6 months later. No increase in tapeworm prevalence within the 237 horses was observed over the course of the study, despite a substantial reduction in the application of anti-tapeworm treatments.

Summary of praziquantel treatments over the study period

Conclusions 

This study demonstrated that by using a diagnostic-led approach compared to an all-group treatment strategy, the application of anti-cestode wormer treatments can be considerably reduced by bi-annual monitoring for tapeworm infection. This, in turn, could help reduce selection pressure for anthelmintic resistance. In total, 99 doses of praziquantel products were administered to the resident population herd; this represents an 86% reduction in anthelmintic administration during the period of the study compared to an interval treatment strategy based on two annual treatments for all horses. Younger horses (1-5 years-old) had a higher proportion of positive test results indicating that anti-tapeworm treatment was required. There was no obvious difference in the proportion of horses that tested positive between autumn and spring.

Additional materials

Information relating to this case study is available as

  1. A podcast
    beva.onlinelibrary.wiley.com/action/downloadSupplement?doi=10.1111%2Fevj.12742&file=evj12742-sup-0001-Podcast.mp3
  2. A video abstract
    EVJ Video Abstract, No 7, Feb 2018 – Use of a saliva-based diagnostic test to identify tapeworm infection in horses in the UK on Vimeo

Declaration of interest

Jacqui Matthews reports an affiliation to Austin Davis Biologics, a commercial entity with a financial interest in materials discussed here.

References

Fogarty, U., del Piero, F., Purnell, R.E., Mosurski, K.R., 1994. Incidence of Anoplocephala perfoliata in horses examined at an Irish abattoir. Vet. Rec. 134, 515-518.

Lightbody, K.L., Davis, P.J., Austin, C.J., 2016. Validation of a novel saliva-based ELISA test for diagnosing tapeworm burden in horses. Vet. Clin. Path. 45, 335-346.

Nielsen, M.K., 2023. Apparent treatment failure of praziquantel and pyrantel pamoate against anoplocephalid tapeworms. Int J Parasitol Drugs Drug Resist. 22, 96-101.

Owen, R.A., Jagger, D.W., Quan-Taylor, R., 1988. Prevalence of Anoplocephala perfoliata in horses and ponies in Clwyd, Powys and adjacent English marches. Vet. Rec. 123, 562-563.

Pavone, S., Veronesi, F., Piergili, Fioretti, D., Mandara, M.T., 2010. Pathological changes caused by Anoplocephala perfoliata in the equine ileocecal junction. Vet. Res. Commun. 34 Suppl 1, S53-56.

Pittaway, C.E., Lawson, A.L., Coles, G.C., Wilson, A.D., 2014. Systemic and mucosal IgE antibody  responses of horses to infection with Anoplocephala  perfoliata. Vet. Parasitol. 199, 32-41.

Proudman C.J., Edwards G.B., 1993. Are tapeworms associated with equine colic? A case control study. Equine Vet J. 25, 224- 674 226. 675 63.

Proudman C.J., French N.P., Trees A.J., 1998. Tapeworm infection is a significant risk factor for spasmodic colic and ileal im- 676 paction colic in the horse. Equine Vet. J. 30, 194-199.