Australian Equine Internal Parasite Guidelines Released

Australian guidelines for equine internal parasite management were released in late January 2025. The research behind these guidelines were published as an invited review in the Australian Veterinary Journal.

There is a supplemental document that provides detailed guidelines that is of use to veterinarians, horse owners, and managers.

The published review was titled Australian Guidelines for Equine Internal Parasite Management. It was authored by A. Beasley, G. Abbas, K. Hughes, C. El-Hage, C. Jacobson, J. Bauquier, E. Wilkes, P. Carrigan, L. Cudmore, J. Hurley, I. Beveridge, M. Nielsen, and A. Jabbar. (Editor’s note: Make sure to come back to MySeniorHorse.com to hear a podcast with Professor Abdul Jabbar, DVM, MSc, about these guidelines.)

An article on the University of Melbourne’s website stated, “New guidelines released by the Australian Equine Parasitology Advisory Panel (AEPAP) will help vets better manage internal parasites in horses, providing information about common parasites, how to control them, and how to test for drug resistance—a growing problem affecting the $1.65 billion a year Australian Thoroughbred industry.”

Australian Guidelines

The guidelines introduction stated, “The emergence of resistance to all available anthelmintic classes over the last few decades has created an urgency for change to approaches to parasite control in the Australian equine industry, as it has on a global scale. Historically, indiscriminate and frequent timed use of a narrow range of anthelmintics has driven widespread selection for resistant cyathostomins and Parascaris spp. Without the adoption of better practices, many farms may find that parasite control becomes both more expensive and less effective.

“Guidelines for parasite control in horses in the USA, Europe and Denmark have been produced by the American Association of Equine Practitioners in the USA, the European Scientific Counsel Companion Animal Parasites and the Danish Veterinary Association, respectively. Many concepts presented by these groups can be logically extrapolated, however, recommendations for horses managed under Australian conditions require consideration of local grazing management practices often conducive to parasite transmission.

“The guidelines presented here have been formulated by the Australian Equine Parasitology Advisory Panel (AEPAP). Strategies are based on data collected through extensive research on Australian equine farms, and evidence available in the scientific literature. Consideration is given to the current levels of anthelmintic resistance to common deworming products and results from national surveys of Australian Thoroughbred breeders and veterinarians are provided throughout for context on current practices.”

Guideline Objectives

The ‘overarching’ objectives of the detailed guidelines were stated as:

To reduce the risk of parasitic disease;
To limit parasite egg shedding into the environment, particularly when favourable conditions for egg and larval survival prevail;
To decrease the frequency of anthelmintic administration and maintain a refugia population through selective use of effective anthelmintics
To determine effective drugs for use on individual properties through the faecal egg count reduction test (FECRT) and/or egg reappearance (ERP); and
To avoid the transmission of resistant parasites between farms through implementation of effective quarantine protocols.

The guideline authors noted, “This final objective is important, given the recently confirmed importation of macrocyclic lactone-resistant cyathostomins in thoroughbred yearlings from Ireland to the USA⁴ and confirmation of macrocyclic lactone resistance on Australian thoroughbred farms.”

Target Parasites

Small strongyles (Cyathostomins) is considered the primary target for mature horses, stated the guidelines. “These parasites are present in up to 72-100% of surveyed Australian horse properties,” noted the report.

For horses under a year of age, ascarids (Parascaris spp) are the primary focus of deworming management.

Tapeworms in horses generally are Anoplocephala perfoliata. Tapeworm infestations in horses are linked to some types of colic. These include spasmodic colic, ileal impaction, and ileocecal intussusception. The use of praziquantel in deworming programs has reduced tapeworm issues. However, resistance of A. perfoliata to praziquantel and pyrantel pamoate has recently been reported in countries around the world.

The guidelines noted that with farm surveillance of equine internal parasites, “Other parasites (bots [Gasterophilus spp], pinworms [Oxyuris equi], tapeworms [Anoplocephala perfoliata], Habronema spp. Draschia and Onchocerca spp.) are typically less of a concern for healthy, well-managed horses and are often controlled as a consequence of managing cyathostomins or Parascaris spp. However, these also have potential to become problematic given the right conditions and so should be included in the farm surveillance protocol.

Collection of Fecal Samples

The guidelines offer a list of equine parasites, the type of test used to detect them, and notes about the parasites. There also is information about the collection and storage of fecal samples. Below is information from the guidelines about collection of fecal samples:

Feces must be fresh
- Direct from rectum where possible (not always practical)
- Freshly passed onto ground (within 4-5 hrs, still moist)
Ability to correctly identify individual horse samples (if not collected from rectum), may require yarding/stabling of horses, or patient observation in the paddock
Collect using gloves, and place individual samples into labelled zip lock bags. Press air out.
1 ball of feces per horse is adequate for performing a fecal egg count (FEC).

“If intending to carry out a larval culture, an extra ball of faeces should be collected into a separate labelled bag. Note: If collected from the ground, contamination with free-living larvae is likely and these will need to be differentiated during examination under the microscope.”

The guidelines also have storage recommendations. They also cover how fecal egg counts are performed.

Included were notes on deworming strategies: “A strongyle fecal egg count carried out at any time can indicate whether an anthelmintic intervention may be required to limit further pasture contamination with eggs and larvae. As part of a targeted treatment approach, FEC of individual horses can be used to inform deworming decisions, preventing unnecessary treatments and slowing the development of anthelmintic resistance.”

The researchers also detail how to identify shedding category (high, medium, or low) of individual horses.

There also were recommendations for pinworms and tapeworms since they are difficult to diagnose from fecal egg counts.

Anthelmintic Resistance

Equine managers in Australia said anthelmintic resistance was an important matter, but “only 29% incorporate FECRTs into their management strategy and 91% are unaware of the anthelmintic resistance profile of their property,” noted the report.

“Anthelmintic resistance among cyathostomins and Parascaris spp. is widespread on Australian horse properties, with the magnitude and prevalence increasing among all available nematocidal drug classes (macrocyclic lactones (MLs), benzimidazoles (BZs) and tetrahydropyrimidines (THPs)),” noted the guidelines. “Recent work carried out by the AEPAP has captured alarming cases of resistance on Australian Thoroughbred farms.”

Parasite Management

The guidelines outline various means of internal parasite management and their effectiveness. This ranged from treating with various drug classes with testing to environmental methods of reducing parasites.

Equine treatment recommendations are offered for various age ranges. These are broken into foals and weanlings, 1-5 year olds, 5-15 year olds, and 15 year olds and up. This Guidance for worm control in each equine age cohort was adapted from AAEP 2024.

Environmental methods included manure removal, mixed-species grazing, and stocking density/pasture resting.

Key Recommendations

The guidelines noted that it “offers evidence-based recommendations for sustainable management of equine internal parasites. To slow further development of anthelmintic resistance, FECs should guide deworming decisions and drug class selection, while FECRTs should be conducted regularly to monitor drug efficacy. These tools, combined with non-chemical strategies to disrupt parasite life cycles, can be integrated into a comprehensive management approach.”