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Abbas G, Ghafar A, McConnell E, Beasley A, Bauquier J, Wilkes EJA, El-Hage C, Carrigan P, Cudmore L, Hurley J, Gauci CG, Beveridge I, Ling E, Jacobson C, Stevenson MA, Nielsen MK, Hughes KJ, Jabbar A. A national survey of anthelmintic resistance in ascarid and strongylid nematodes in Australian Thoroughbred horses. Int J Parasitol Drugs Drug Resist 2024; 24:100517. [PMID: 38064906 PMCID: PMC10757041 DOI: 10.1016/j.ijpddr.2023.11.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2023] [Revised: 11/19/2023] [Accepted: 11/19/2023] [Indexed: 01/02/2024]
Abstract
This study quantified the extent of anthelmintic resistance (AR) in ascarid and strongylid nematodes against commonly used anthelmintics in Australian Thoroughbred horses. Faecal egg count reduction tests (FECRTs, n = 86) and egg reappearance period (ERP) tests were conducted on 22 farms across Australia. Faecal egg counts (FECs) were determined using the modified McMaster technique, and percent faecal egg count reduction (%FECR) was calculated using the Bayesian hierarchical model and hybrid Frequentist/Bayesian analysis method. The results were interpreted using old (published in 1992) and new (2023) research guidelines of the World Association for the Advancement of Veterinary Parasitology (WAAVP). The species composition of strongylid nematodes was detected utilising a DNA-metabarcoding method using pre- and post-treatment samples. Resistance was observed in strongylid nematodes to commonly used single-active and combination anthelmintics, including ivermectin (IVM %FECR range: 82%-92%; 95% lower credible interval (LCI) range: 80%-90%), abamectin (ABM: 73%-92%; 65%-88%), moxidectin (MOX: 89%-91%; 84%-89%), oxfendazole (OFZ: 0%-56%; 0%-31%) and its combination with pyrantel (OFZ + PYR: 0%-82%; 0%-78%). Resistance in Parascaris spp. was observed to IVM (10%-43%; 0%-36%), ABM (0%; 0%) and MOX (0%; 0%). When the new thresholds recommended by the WAAVP were used, AR was detected in six additional FECRTs for strongylids and three more tests for Parascaris spp., introducing resistance to OFZ and OFZ + PYR in the latter. Shortened ERPs (4-6 weeks) of strongylids were observed in 31 FECRTs in which AR was not detected at 2 weeks post-treatment for all the anthelmintics tested. Among cyathostomins, Cylicocyclus nassatus, Cylicostephanus longibursatus and Coronocyclus coronatus were the most prevalent species at 2 weeks post-treatment, whereas the main species appearing at five weeks following treatments with macrocyclic lactones were Cylicocyclus nassatus, Cylicostephanus longibursatus and Cylicocyclus ashworthi. After treatment with OFZ + PYR, the latter three, plus Coronocyclus coronatus and Cyathostomum catinatum, were detected at 5 weeks post-treatment. Overall, the study highlights the prevalence of AR in both ascarids and strongylid nematodes against commonly used anthelmintic products to control worms in Australian horses. The results indicate that ML combination products provided acceptable efficacy at 2 weeks. However, ERP calculations suggest that products work less effectively than previously measured. It is suggested to regularly monitor the efficacy of the anthelmintics and consider changing the worm control practices to better manage worms and AR in Australian horses.
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Affiliation(s)
- Ghazanfar Abbas
- Melbourne Veterinary School, The University of Melbourne, Werribee, Victoria 3030, Australia
| | - Abdul Ghafar
- Melbourne Veterinary School, The University of Melbourne, Werribee, Victoria 3030, Australia
| | - Emma McConnell
- Centre for Animal Production and Health, Murdoch University, Murdoch, Western Australia, Australia
| | - Anne Beasley
- School of Agriculture and Food Sustainability, University of Queensland, Gatton, Queensland 4343, Australia
| | - Jenni Bauquier
- Melbourne Veterinary School, The University of Melbourne, Werribee, Victoria 3030, Australia
| | | | - Charles El-Hage
- Melbourne Veterinary School, The University of Melbourne, Werribee, Victoria 3030, Australia
| | - Peter Carrigan
- Scone Equine Hospital, Scone, New South Wales 2337, Australia
| | - Lucy Cudmore
- Scone Equine Hospital, Scone, New South Wales 2337, Australia
| | - John Hurley
- Swettenham Stud, Nagambie, Victoria 3608, Australia
| | - Charles G Gauci
- Melbourne Veterinary School, The University of Melbourne, Werribee, Victoria 3030, Australia
| | - Ian Beveridge
- Melbourne Veterinary School, The University of Melbourne, Werribee, Victoria 3030, Australia
| | - Elysia Ling
- Melbourne Veterinary School, The University of Melbourne, Werribee, Victoria 3030, Australia
| | - Caroline Jacobson
- Centre for Animal Production and Health, Murdoch University, Murdoch, Western Australia, Australia
| | - Mark A Stevenson
- Melbourne Veterinary School, The University of Melbourne, Werribee, Victoria 3030, Australia
| | - Martin K Nielsen
- M.H. Gluck Equine Research Center, Department of Veterinary Science, University of Kentucky, Lexington, KY, USA
| | - Kristopher J Hughes
- School of Agricultural, Environmental and Veterinary Sciences, Charles Sturt University, Wagga Wagga, New South Wales 2650, Australia
| | - Abdul Jabbar
- Melbourne Veterinary School, The University of Melbourne, Werribee, Victoria 3030, Australia.
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Abbas G, Bauquier J, Beasley A, Jacobson C, El-Hage C, Wilkes EJA, Carrigan P, Cudmore L, Hurley J, Beveridge I, Nielsen MK, Hughes KJ, Stevenson MA, Jabbar A. Worm control practices used by Thoroughbred horse managers in Australia: A national survey. Vet Parasitol 2024; 327:110116. [PMID: 38244523 DOI: 10.1016/j.vetpar.2024.110116] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2023] [Revised: 01/09/2024] [Accepted: 01/10/2024] [Indexed: 01/22/2024]
Abstract
This study assessed worm control practices used by Australian Thoroughbred farm managers with an online questionnaire survey. The questionnaire comprised 52 questions (close-ended: 44; open-ended: 8) about farm demography and general husbandry practices, farm managers' knowledge of gastrointestinal nematodes (GIN) and their importance, diagnosis, worm control strategies and anthelmintics, anthelmintic resistance (AR) and grazing management. Following the pilot survey, the link for the questionnaire survey was sent to all (n = 657) registered members of the Thoroughbred Breeders Australia on 12th April 2020. The response rate for the questionnaire was 18.5% (122 of 675). The farm managers reported a good understanding of GIN and their importance in different age groups of horses as most respondents (70% of 122) perceived worm-related illness to be more important in young (i.e., foals, weanlings and yearlings) than adult (> 3 years old) horses. Although most respondents (93%, 113 of 122) used anthelmintics prophylactically to control GIN, only 15% (18 of 122) observed worm-related illness in their horses. Just under 40% of respondents were performing faecal egg counts, with less than 20% using the results of faecal egg counts to guide deworming decisions. The interval-based deworming strategy was the most common method (≥55% of 122 respondents) to control GIN in all age groups of horses. Macrocyclic lactones were the first choice of anthelmintics for all age groups of horses. Although the majority of respondents (88%, 107 of 122) perceived resistance in GIN against commonly used anthelmintics as an important issue in managing worms in horses, only 29% assessed the efficacy of anthelmintics and 91% (111 of 122) were unaware of AR on their properties. Grazing management practices, such as manure removal, were more frequently performed on smaller paddocks (<0.20 ha: 58%) than on larger paddocks (>0.20 ha: 18%). Multiple correspondence analyses showed that the likelihood of suboptimal worm control practices on small farms (n = ≤50 horses) was greater than that of medium (n = 51-100) and large (n = >100) farms. This study provides insights into the demography of Thoroughbred farms in Australia, husbandry practices used by stud managers and their knowledge about worms, control options and AR concerns, thereby paving the way for taking any initiatives to address the problem of AR in GIN of Australian Thoroughbred horses.
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Affiliation(s)
- Ghazanfar Abbas
- Melbourne Veterinary School, The University of Melbourne, Werribee, Victoria 3030, Australia
| | - Jenni Bauquier
- Melbourne Veterinary School, The University of Melbourne, Werribee, Victoria 3030, Australia
| | - Anne Beasley
- School of Agriculture and Food Sustainability, University of Queensland, Gatton, Queensland, Australia
| | - Caroline Jacobson
- Centre for Animal Production and Health, Murdoch University, Murdoch, Western Australia, Australia
| | - Charles El-Hage
- Melbourne Veterinary School, The University of Melbourne, Werribee, Victoria 3030, Australia
| | | | - Peter Carrigan
- Scone Equine Hospital, Scone, New South Wales, Australia
| | - Lucy Cudmore
- Scone Equine Hospital, Scone, New South Wales, Australia
| | - John Hurley
- Swettenham Stud, Nagambie, Victoria, Australia
| | - Ian Beveridge
- Melbourne Veterinary School, The University of Melbourne, Werribee, Victoria 3030, Australia
| | - Martin K Nielsen
- M.H. Gluck Equine Research Center, Department of Veterinary Science, University of Kentucky, Lexington, KY, USA
| | - Kristopher J Hughes
- School of Agricultural, Environmental and Veterinary Sciences, Charles Sturt University, Wagga Wagga, New South Wales, Australia
| | - Mark A Stevenson
- Melbourne Veterinary School, The University of Melbourne, Werribee, Victoria 3030, Australia
| | - Abdul Jabbar
- Melbourne Veterinary School, The University of Melbourne, Werribee, Victoria 3030, Australia.
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Abbas G, Ghafar A, Beasley A, Stevenson MA, Bauquier J, Koehler AV, Wilkes EJA, McConnell E, El-Hage C, Carrigan P, Cudmore L, Hurley J, Gauci CG, Beveridge I, Jacobson C, Nielsen MK, Hughes KJ, Jabbar A. Understanding temporal and spatial distribution of intestinal nematodes of horses using faecal egg counts and DNA metabarcoding. Vet Parasitol 2024; 325:110094. [PMID: 38091893 DOI: 10.1016/j.vetpar.2023.110094] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2023] [Revised: 11/30/2023] [Accepted: 11/30/2023] [Indexed: 12/25/2023]
Abstract
This study reports the spatial and temporal distribution of ascarid and strongylid nematodes in Thoroughbred horses by age category across different climatic zones in Australia over an 18-month period. Faecal samples (n = 2046) from individual horses were analysed using the modified McMaster technique for faecal egg counts (FECs). Strongylids were identified using PCR-directed next-generation sequencing of the second internal transcribed spacer (ITS-2) of the nuclear ribosomal DNA. Yearlings had the highest prevalence (82%) of strongyle eggs followed by weanlings (79%), foals (58%), wet mares (49%) and dry mares (46%). For Parascaris spp., foals had the highest prevalence (35%) followed by weanlings (21%) and yearlings (10%). The highest mean FECs for Parascaris spp. were observed in foals (525 eggs per gram [EPG] of faeces) while those for strongyles were in yearlings (962 EPG). Among horses that were classified as adults at the time of sampling, 77% (860 of 1119) of mares were low (i.e., <250 EPG) strongyle egg-shedders. Mean strongyle FEC counts were highest in the Mediterranean (818 EPG) followed by summer (599 EPG), winter (442 EPG), and non-seasonal (413 EPG) rainfall zones. Twenty-six nematode species were detected, with Cylicostephanus longibursatus (26.5%), Cylicocyclus nassatus (23.7%) and Coronocyclus coronatus (20.5%) being the most frequently detected species. Their richness and relative abundance varied with horse age, season and climatic zone. In addition, Strongylus equinus and Triodontophorus spp. (T. brevicauda and T. serratus) were also detected. This comprehensive study elucidates spatial (climatic zone) and temporal (i.e., seasonal) trends in prevalence and burdens of intestinal nematodes in Australian horses using non-invasive conventional and molecular methods. The information presented in this study is crucial for developing integrated management strategies to control horse parasites in farmed horses.
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Affiliation(s)
- Ghazanfar Abbas
- Melbourne Veterinary School, The University of Melbourne, Werribee, Victoria 3030, Australia
| | - Abdul Ghafar
- Melbourne Veterinary School, The University of Melbourne, Werribee, Victoria 3030, Australia
| | - Anne Beasley
- School of Agriculture and Food Sustainability, University of Queensland, Gatton, Queensland 4343, Australia
| | - Mark A Stevenson
- Melbourne Veterinary School, The University of Melbourne, Werribee, Victoria 3030, Australia
| | - Jenni Bauquier
- Melbourne Veterinary School, The University of Melbourne, Werribee, Victoria 3030, Australia
| | - Anson V Koehler
- Melbourne Veterinary School, The University of Melbourne, Werribee, Victoria 3030, Australia
| | | | - Emma McConnell
- Centre for Animal Production and Health, Murdoch University, Murdoch, Western Australia, Australia
| | - Charles El-Hage
- Melbourne Veterinary School, The University of Melbourne, Werribee, Victoria 3030, Australia
| | - Peter Carrigan
- Scone Equine Hospital, Scone, New South Wales 2337, Australia
| | - Lucy Cudmore
- Scone Equine Hospital, Scone, New South Wales 2337, Australia
| | - John Hurley
- Swettenham Stud, Nagambie, Victoria 3608, Australia
| | - Charles G Gauci
- Melbourne Veterinary School, The University of Melbourne, Werribee, Victoria 3030, Australia
| | - Ian Beveridge
- Melbourne Veterinary School, The University of Melbourne, Werribee, Victoria 3030, Australia
| | - Caroline Jacobson
- Centre for Animal Production and Health, Murdoch University, Murdoch, Western Australia, Australia
| | - Martin K Nielsen
- M.H. Gluck Equine Research Center, Department of Veterinary Science, University of Kentucky, Lexington, KY, USA
| | - Kristopher J Hughes
- School of Agricultural, Environmental and Veterinary Sciences, Charles Sturt University, Wagga Wagga, New South Wales 2650, Australia
| | - Abdul Jabbar
- Melbourne Veterinary School, The University of Melbourne, Werribee, Victoria 3030, Australia.
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