Parasite management practices used by owners of Australian Pony Club horses and the factors influencing their decision‐making processes

Abstract

There is a lack of information on horse parasite management practices currently used by individual horse owners in Australia. A voluntary, anonymous online survey was developed for and distributed by Pony Club Australia to its members seeking information on horse population; housing; paddock, manure and parasite management; and owner attitudes. From a total of 98 completed responses, 95/98 of participants indicated their horses spent time in paddocks, 91/98 administered anthelmintics, 42/98 guessed their horse's body weight for dosing, 78/98 recalled the dewormer brand or active ingredient last administered, macrocyclic lactones represented the most common dewormer class used (75/78) and veterinarians and scientific papers were rated highly as trusted sources of information (83/97 and 80/97 respectively). Barriers to managing parasites included time and cost, peer practices, environmental challenges and inconsistent information regarding parasite control. Owners navigated through these supported by a sense of agency to improve their knowledge and seek expert advice, as well as creating healthy environments for their horses coupled with good pasture management. This study highlights some risky practices for anthelmintic use and opportunities for increased veterinary engagement and owner education to adopt a more holistic approach to horse parasite management.

In the 1960s, equine parasite management had been governed by interval dosing regimens of anthelmintics. ¹ Consequently, helminths such as Strongylus vulgaris had become uncommon in domestic horse populations, whereas selection pressure had contributed to the development of anthelmintic resistance (AR) in other parasites such as cyathostomins, Parascaris spp. and Oxyuris equi. ² More recently, the apparent re‐emergence of S. vulgaris, ³ and the apparent lack of efficacy of drugs against Anoplocephala spp. ⁴ has parasitologists concerned about equine health and welfare globally. Without new anthelmintics on the horizon, slowing the spread of AR seems more urgent than ever.

Horse owners are regarded as the primary decision‐makers concerning horse health care. In an era of unlimited online advice and access to over‐the‐counter anthelmintics, little is known about their approach to parasite control, and whether current parasite management decisions are based on traditional practices or if horse owners have been adopting recommended updated methods addressing AR. Owner decisions about parasite management are potentially modifiable and identifying opportunities for intervention and further research was a primary aim of this study.

A voluntary, anonymous online survey was conducted from February to March 2023, to explore knowledge, attitudes and practices of Australian Pony Club horse owners concerning horse parasite management (HPM) using SurveyMonkey® software (see Appendix). Twenty‐seven close‐ended (multiple choice and self‐assessment 5‐point Likert scales) and seven open‐ended questions sought information on horse population and housing, manure and paddock management, equine parasites, parasite management, deworming practices, veterinarian involvement, information sources and owner attitudes.

After an initial pilot validation process, a nonprobability volunteer sampling frame was used to recruit as many participants as possible for the study, precluding sample size calculations. This method enabled a quick and inexpensive method of collecting data within a narrow timeframe. Pony Club Australia promoted the survey invitation to its nationwide adult membership base through newsletters and their Facebook page. Ethics approval was granted by Charles Sturt University Human Research Ethics Committee (H22329).

A total of 98 complete surveys were received. Caution must be exercised with this number of responses and generalising the results to horse populations outside this study. Whilst the sample size is comparable with other Australian equine‐related questionnaires ⁵ , ⁶ and earlier Pony Club interview survey responses, ⁷ , ⁸ self‐selection, internet coverage, social desirability and researcher bias may present limitations. Survey fatigue and nonresponse bias were mitigated using branching logic to skip questions irrelevant to the participant. Descriptive statistics were calculated for numerical and categorical data using Microsoft Excel. Categories were developed for open‐ended text items as responses were coded iteratively into themes using NVivo‐12 software. Results revealed that HPM practices varied among respondents.

Horse owners cared for a median number of three horses of which 96.9% (95/98) had access to grazing in paddocks which ranged in size from 0.5 to 300 acres. Grazing management was a key component of HPM in Australian Pony Club horses and included subdivisions into smaller paddocks (84.2%, 80/95), rotational grazing (73.7%, 70/95), mixed grazing (24.2%, 23/95) and paddock manure removal (61.1%, 58/95). This paddock management was consistent with other Australian studies ⁵ , ⁶ but more variation has been described in other countries for manure removal such as Scotland (76%), ⁹ Italy (21.3%) ¹⁰ and France (2.6%). ¹¹ Manure recycling played a key role in paddock management in this study including composting (49.0%, 48/98) and spreading in conjunction with paddock rotation (51.0%, 50/98).

In addition to grazing management, chemical control played a major role in HPM with nearly all (92.9%, 91/98) respondents using anthelmintics and 78/98 (79.6%) of them able to recall a brand name or active ingredient. For respondents who answered this question, active ingredient(s) (85.1%, 80/94), product efficacy (90.4%, 85/94), likely parasite(s) in horses (84.9%, 79/93) or results of egg count tests (82.8%, 78/93) were considered very to extremely important when selecting an anthelmintic. More than half of owners in the present study considered dung beetles to be important in HPM and were aware of the toxic effects of anthelmintics on these nontarget bio‐assets and some practiced quarantine deworming (Figure 1). Of concern, however, is that almost one‐fifth of respondents were unsure about the importance of quarantine practices or dung beetles in the selection of anthelmintics for their horses, and about 10% of respondents considered these factors not at all important. These knowledge gaps and resultant risky HPM practices would likely contribute to worsening AR in Australia, and intervention to mitigate these risks would be a priority. One respondent suggested that a subsidised faecal egg count (FEC) testing programme for Pony Club members may encourage healthy worm control practices.

Figure 1.

Dewormer usage over 12 months indicated in a survey of horse owners (n = 98). FEC – Faecal Egg Count. † FEC results were offered voluntarily as an ‘Other’ use option. ‡ Preventive usage.

Since the rather haphazard approach to HPM reported in earlier studies of Australian Pony Club horses ⁸ and despite the frequent use of anthelmintics in the current study, including interval dosing (Figure 1), the observed trend towards a more strategic approach to HPM, including use of FEC testing is encouraging. This suggests that some horse owners were informed about the detrimental effects of interval dosing and used this knowledge to underpin their decisions on this management practice. The current adoption rate was higher than that reported in other studies at 16% and 2.6% in Australia, ⁵ , ⁶ 19% in Scotland ⁹ and 9.3% in Italy. ¹⁰ The present study also indicates a progressive step towards targeted deworming practices including not deworming all horses at the same time (20.9%, 18/86), not at all (11.6%, 10/86) or with different combinations of dewormers (15.1% 13/86).

Macrocyclic lactones (ML: moxidectin, ivermectin and abamectin, with or without praziquantel) were used by 96.2% (75/78) and praziquantel by 74.4% (58/78) of respondents, comparable with other studies. ⁸ , ⁹ Benzimidazoles (BZ: oxfendazole, fenbendazole) were used by 30.8% (24/78) of respondents and tetrahydropyrimidines (THP: pyrantel embonate, morantel tartrate) were used by 32.1% (25/78) of respondents in combination with ML or BZ. About one‐third of horse owners used more than one drug class (not as a combination all‐wormer), suggesting use of drug rotation in their HPM. Of concern is the number of owners (approximately one in five) who could not recall a brand name or active ingredient administered to their horse(s). This suggests that records were not kept, hinting at a lack of concern about this evidence‐based information and resulting in risky deworming practices. Most respondents had heard of AR (85.7%, 84/98), FECs and Faecal Egg Count Reduction Tests (FECRTs) (95.9%, 94/98). Just over half of respondents used FECs before deworming. Of the owners that indicated that they had not used a FEC or FECRT to inform deworming decisions, several barrier factors appeared to have contributed to this decision. These factors included the cost of FECs and additional veterinary fees; time involved in collecting fresh manure samples or transporting manure samples or horses to a remote testing laboratory; managing FECs for large numbers of horses; and a lack of knowledge or understanding of FECs. Perceived barriers that affect the way horse owners manage their parasites in general are presented in Figure 2.

Figure 2.

Barrier factors affecting horse parasite management in a survey of horse owners (n = 60).

Guesswork (42.9%, 42/98) and horse weight tape (32.7%, 32/98) practices featured as methods for estimating horse body weight (BW) (Figure 3). Recent guidelines for diagnosing AR using FECRTs recommend adding 15%–20% to the weight tape estimate to reduce the chances of underdosing. ¹² It is of concern, then, that BW was incorrectly estimated, resulting in another risky deworming practice of over‐ or underdosing with anthelmintics. This holds critical implications for lowered drug efficacy and onset of AR in susceptible worm populations. Furthermore, several smart phone applications now exist for estimating horse BW, and social media platforms have seen a rise in engagement with general‐public audiences for educational purposes. ¹³ These are opportunities to explore further to educate horse owners regarding HPM.

Figure 3.

Methods of body weight estimation of horses for dosing in a survey of horse owners (n = 98).

Veterinarians were rated high to very high as a trusted source of information (85.6%, 83/97) by respondents as were scientific papers (82.5%, 80/97), reflecting an upward trend from results reported 20 years ago (16%). ⁷ Scientific references informing the current study encompass peer‐reviewed research and research‐supported industry publications beyond Pony Club. However, some questions remain unanswered. How horse owners recognised internal parasite infections was not established. Nearly 10% of owners skipped this question and only one‐quarter reported a veterinary diagnosis of their horses' parasites. (Figure 4). Visual inspection of manure, as validated by one respondent, may identify expelled parasites after anthelmintic treatment. It is uncertain if the owners who administered anthelmintic treatments to horses based on self‐diagnosed parasite infections did so correctly. The details of any veterinary recommendations made to owners were not reported in the current survey.

Figure 4.

Equine parasites reported in a survey of horse owners (n = 90).

Despite an encouraging trend in adoption of up‐to‐date parasite control measures, owners still employed some risky practices, inadvertently increasing selection pressure for and encouraging spread of AR. Owner agency, good pasture management and creating healthy environments for horses, as well as up‐to‐date parasite control information were driving factors for navigating perceived barriers. We identified knowledge gaps around choice of dewormer, target parasites, when to deworm, quarantine practices, FEC monitoring, BW estimation and record keeping. Increasing veterinary engagement in tandem with relevant educational programmes could empower Pony Club horse owners to improve their decision‐making regarding HPM. Veterinarians emerged as a very important source of HPM information ideally placed to advise on slowing AR, including on‐farm opportunities for an integrated approach to HPM and less reliance on chemicals. ¹⁴ , ¹⁵ A subsidised FEC programme to benefit Pony Club horse owners warrants exploration, mitigating an important financial barrier to adopting parasite monitoring practices.

Conflicts of interest and sources of funding

The authors declare no conflicts of interest or sources of funding for the work presented here.

Ethical statement

The study was approved by Charles Sturt University Human Research Ethics Committee (Protocol number H22329). Informed consent was obtained from all participants involved in the study.

APPENDIX A.

A.1. Questionnaire

1. CONSENT: Clicking on the ‘Agree’ button below indicates that: You have read and understood the information statement. You have been given the opportunity to have questions answered to your satisfaction. You voluntarily agree to participate. You are at least 18 years of age. You are the primary manager or carer of the horses and/or ponies that you take to Pony Club events. If you do not wish to participate in the research study, please decline participation by clicking on the ‘Disagree’ button.

2. How many horses and ponies do you manage and/or care for in total?

3. Which of the following best describes where your horse(s) live? (You may select more than one option if applicable) My horse(s) spend time in stables My horse(s) spend time in yards My horse(s) spend time in paddocks.

4. What is the total area (in acres) your horse(s) have access to?

5. Is that total area divided into paddocks? Yes No.

6. Do you rotate your horse(s) and paddocks for grazing? Yes No

7. Does your horse share paddocks with other horses? Yes No

8. Do other livestock, such as cattle or sheep, graze with your horse(s)? Yes No.

9. Are there dung beetles in the paddocks where your horse(s) graze? Yes No Don't know.

10. How often is manure usually removed from the paddocks where your horse(s) graze? Daily Twice a week Weekly Fortnightly Monthly Seasonally Annually Never Other (please specify).

11. How often is your horse(s) stable or stall usually mucked out? At least once a day, Every second day, Twice a week, Once a week, Other (please specify).

12. How often would your horse(s) stable or stall bedding be completely renewed? Weekly Fortnightly Monthly Once a season A couple of times per year Other (please specify).

13. Please describe how the soiled bedding is disposed of:

14. How often is manure usually removed from your horse(s) yards? Daily or more often Every second day Twice a week Weekly Fortnightly Monthly Never Other (please specify).

15. Please describe the way(s) you manage the manure:

16. Please indicate all of the parasites that your horse(s) has been infected with or shown signs of: Large strongyles Small strongyles (Cyathostomins) Roundworm ‐ Ascarids (Parascaris species) Small stomach worm (Trichostrongylus axei) Stomach worm (Draschia & Habronema species) Botfly (Gasterophilus species) Intestinal threadworm (Strongyloides westeri) Tapeworm (Anaplocephala perfoliata) Pinworm (Oxyuris equi) Lungworm (Dictyocaulus arnfieldi) Neck threadworm (Onchocerca species) Sandflies (Culicoides species) Flies Lice Mosquitoes Mites Ticks Liver fluke (Fasciola hepatica).

17. Have any of these parasites been diagnosed by a vet?

18. Over the last 12 months what methods have been used to manage parasites for your horse(s)? (Please select all that apply) Fly veil Mesh rug Other type of rug Repellents (external) Body washes Insecticides Dewormer (anthelmintic) medication Physical removal (e.g., botfly knife) Other (please specify).

19. When has your horse(s) been treated with a dewormer in the last 12 months? (Please select all that apply) Spring and autumn Before AND after competition Before OR after competition (not both) After mingling with other unknown horses When required by quarantine regulations When required by agistment or spelling regulations Routinely every 4–8 weeks Routinely every 3 months When signs or symptoms were noticed Periodically in case deworming was needed Other (please specify).

20. Which brands of dewormers (anthelmintics) have been used for your horse(s) in the last 12 months?

21. Were all your horses dewormed at the same time? Yes No.

22. Do you have some horses that are not dewormed at all? Yes No.

23. If you have more than one horse, do you use the same brand of dewormer for all of them? Yes No, different dewormers are used on different horses.

24. How do you measure or estimate the weight of your horse(s)? Livestock weighing scales Horse weight tape Formula ‐ calculation using height, length and/or other details (manual or app) Guess Other (please specify).

25. How would you rate your level of trust in the following sources of information for managing horse(s) parasites? (Very low Low Moderate High Very high) Friends and family Colleagues Neighbours Your own knowledge and experience Your own professional training Tradition / habit Veterinarian Farrier Other horse professionals Feed supply shop Pony club Internet Social media Horse magazines Scientific papers.

26. Have you heard of anthelmintic resistance? Yes No, not before now.

27. Have you heard of Faecal Egg Counts (FECs) or Faecal Egg Count Reduction Tests (FECRTs)? Yes No, not before now.

28. Do you or does your vet carry out FECs or FECRTs on your horse(s) before deworming? Yes No Not sure.

29. How important do you consider each of the following factors are for selecting a dewormer? (Not sure Not at all important Somewhat important Very important Extremely important) Product branding Active ingredient(s) Price Product efficacy Current industry practice Type of work done by the horse(s) Quarantine practices Likely parasite(s) in the horse(s) Season Climate Geography Number of horses Age of horse(s) Health of horse(s) Horse's diet Results of egg count test Local dung beetle population.

30. How often is your horse(s) seen by a veterinarian? Annually for a wellness check, Regularly, more than once a year, Regularly, less than once a year, Only when there is a health problem, Have not needed a vet.

31. Over the last 12 months, have you discussed ways to manage your horse(s) parasites with a vet? Yes No.

32. Over the last 12 months, have you discussed FECs or FECRTs with a vet? Yes No.

33. Please indicate how you respond to the following statements: (Strongly disagree Disagree Neither agree nor disagree Agree Strongly agree) Dewormers (anthelmintics) are an effective way of managing parasites. Anthelmintic resistance is a general concern. Anthelmintic resistance is a concern for my horse(s). I don't know enough about anthelmintic resistance. FECs are a useful way to monitor worm egg counts. It takes too long to wait for FEC results. FECs are expensive in comparison to dewormers. I would like to know more about horse parasite management. I would like to know more about FECs and FECRTs. I can talk easily with my horse's vet about parasite management. Horse manure is a beneficial fertiliser. Time cost is a major factor in horse care. Financial cost is a major factor in horse care.

34. What, if any, barriers affect the way you manage your horse(s)' parasites and what inspires you to move through these barriers?

35. Please enter any comments or further information you would like to add about your horses and their parasites:

Thank you for your participation. Please click the ‘Done’ button now to finalise your survey.

Data availability statement

The data that support the findings of this study are available from the corresponding author upon reasonable request.