Ivermectin: A cornerstone of cattle and sheep management in Australia

Livestock production is one of the cornerstones of Australian agriculture. Cattle and sheep play a pivotal role in the nation’s economy and rural livelihoods across the country, so maintaining their health is crucial for both productivity and profitability. 

One of the most powerful tools to aid this endeavour is ivermectin, a broad-spectrum antiparasitic that forms a key part of most integrated parasite management strategies. 

This guide will provide a comprehensive look into ivermectin and its use for cattle and sheep management, including the parasites it prevents, its benefits, and tips for combating resistance. 

 

What is ivermectin? 

Ivermectin is a broad-spectrum antiparasitic drug that was developed in the 1970s. It was originally only used in veterinary medicine, but now it’s also commonly used in antiparasitics that producers can purchase and administer themselves safely to support the health of their livestock. 

Ivermectin is also used in tablet and topical form to treat certain parasitic infections in humans. 

Why use ivermectin? 

Ivermectin has become indispensable for controlling a wide range of internal and external parasites in livestock. In a nutshell, ivermectin: 

• Controls mature and immature stages of a variety of common internal parasites
• Effectively treats external parasites like ticks, lice, and mites; reducing irritation and secondary infections 
• Prevents infestations from breaking out during high-risk periods, especially in tropical and subtropical regions prone to ticks 
• Reduces the risk of flystrike, a common and highly dangerous parasite, amongst sheep

How does ivermectin work? 

Ivermectin works by disrupting parasites’ nervous systems, causing paralysis and eventually, death. It’s highly effective against gastrointestinal worms, lungworms, lice, mites, and other arthropods. 

How long does it take for ivermectin to kill parasites?

Ivermectin works quickly to control parasites in livestock, typically taking effect within 24 to 48 hours after it’s administered. Once absorbed, it targets and paralyses parasites by disrupting their nerve and muscle function, effectively eliminating them from the animal’s system. 

The speed of action can vary slightly depending on the parasite type, the method of delivery (oral, injectable, or pour-on), and the overall health of the animal. To ensure effective parasite control and minimise the likelihood of resistance, always deliver the recommended dosage and monitor livestock after antiparasitic application.

How is ivermectin administered to livestock? 

Ivermectin is available in a few different formulations, including injectable, pour-on, and oral doses. This is beneficial for producers as it provides flexibility of application across different livestock and contexts. 

Why use ivermectin for cattle and sheep? 

Parasitic infestations in cattle and sheep can pose serious health, economic, and productivity risks, which is why many farmers and producers choose to administer ivermectin to their livestock. 

Here are some of the benefits of using ivermectin for cattle and sheep:

• Enhanced productivity: Parasite infections in cattle and sheep can impact weight gain, milk yield, fleece quality, and reproduction rates. By effectively controlling parasites, ivermectin helps livestock reach their genetic potential, and boosts productivity and profitability. 
• Improved animal welfare: Parasites can cause significant stress and discomfort to animals, leading to overall poor health and secondary infections. Ivermectin alleviates this burden and contributes to the holistic wellbeing of livestock. 
• Economic benefits: Healthier livestock require fewer interventions, such as veterinary treatments and supplementary feed, reducing costs for producers. It’s also important to note that when productivity levels are affected, economic downturn is almost inevitable – so maintaining animal health is the key to avoiding major financial losses. 

Which parasites can be controlled using ivermectin? 

Ivermectin is one of the most potent, effective antiparasitic compounds around, and one of its key benefits is its broad-spectrum activity against a wide range of parasites. 

Common parasites found in Australia that can be controlled using ivermectin for cattle include: 

• Gastrointestinal nematodes
  • Small brown stomach worm (including inhibited stages)
  • Barber’s pole worm
  • Stomach hair worm
  • Intestinal hair worm
  • Small intestinal worm
  • Nodule worm
  • Whip worm
  • Intestinal threadworm
  • Thin necked intestinal worm (immature stages) 
• Lungworms (adult and immature stages) 
• Eye worm (adult stages) 
• Sucking and biting lice

• Mites 
• Buffalo flies
• Cattle ticks 

 

Sheep in Australia are susceptible to a number of parasites that can be controlled using ivermectin, including:

• Gastrointestinal parasites
  • Barber’s pole worm
  • Black scour worm
  • Intestinal threadworm
  • Large bowel worm
  • Large-mouthed bowel worm
  • Large stomach worm
  • Small brown stomach worm
  • Small intestinal worm
  • Stomach hair worm
  • Thin necked intestinal worm
  • Whip worm
• Sheep itch mites 
• Nasal bots 
• Nodule worms
• Large lungworms
• Lice
• Mites

For a comprehensive list of the parasites targeted by your chosen ivermectin product, please refer to the product label. 

Ivermectin and parasite resistance 

While ivermectin is highly effective at controlling parasites, overuse and misuse have led to parasite resistance in some regions. Resistance occurs when parasites survive treatment and pass on their resistant genes, rendering the drug less potent. 

Strategies to minimise parasite resistance

There are a number of strategies we recommend employing to minimise resistance amongst your herd or flock: 

• Rotating active ingredients: To reduce the risk of resistance, avoid relying solely on ivermectin or other macrocyclic lactone compounds. Incorporate products with different active ingredients, like doramectin, moxidectin, abamectin, and levamisole for cows, and albendazole, fenbendazole, oxfendazole, abamectin, and levamisole for sheep. 

• Conducting fecal egg count (FEC) tests: Regularly monitor parasite burdens using fecal egg count tests to assess the effectiveness of treatments and tailor your parasite control programs accordingly. 

• Using combination treatments: Particularly important with sheep, incorporate products that combine multiple active ingredients to target parasites through different modes of action. This will slow resistance development as a result. 

• Adopting an integrated pest management strategy: Combine chemical control with non-chemical methods such as grazing management and rotational grazing. 

Other antiparasitics for livestock in Australia

As well as ivermectin, there are a number of powerful antiparasitic products available to Australian producers. Here are some other active ingredients to consider: 

• • Benzimidazoles (BZs): Particularly effective against gastrointestinal worms in both sheep and cattle. Examples include albendazole and fenbendazole.

• Levamisole: A narrow-spectrum anthelmintic that targets gastrointestinal worms in both sheep and cattle. 

• Moxidectin: Similar to ivermectin, but with longer residual activity and no meat withholding period. Used predominantly for cattle. 

• Doramectin: Used to control doramectin-sensitive internal and external parasites amongst cattle. 

• Abamectin: Used for both cattle and sheep to control and treat abamectin-sensitive strains of internal and external parasites. 

• Closantel: Effective against blood-feeding parasites, such as barber’s pole worm, in sheep only. 

• Spinosad: Targets lice and flies in sheep only. 

There are a number of factors to consider when selecting the appropriate formula, including the target parasites, any established resistance patterns, and management practices. Always read the product label to learn more about the chemical compound you’re considering and ensure it will meet your needs.

Top tips for using ivermectin for producers

Before you incorporate ivermectin – or any other antiparasitic compound – into your pest management strategy, consider these recommendations: 

• Understand your parasite challenges: Identify the parasites affecting your herd or flock and tailor your program accordingly. Using the wrong compounds is not only unhelpful and could broaden resistance, but it could also be potentially dangerous for your livestock.

• Follow best practices for administration: Adhere to recommended dosages, withdrawal periods, and administration techniques to maximise the efficacy of your chosen product and ensure meat and milk safety.

• Rotate and combine treatments: Integrate ivermectin with other active ingredients and control strategies to mitigate resistance risks. 

• Seek professional advice: Consult with your veterinarian to design a comprehensive parasite management plan for your herd or flock. 

The future of ivermectin in livestock farming

As resistance becomes a growing concern, the livestock industry must adopt sustainable practices to preserve ivermectin’s efficacy. Research into new active ingredients and management strategies will be essential to addressing the evolving challenges of parasite control. 

For Australian cattle and sheep producers, ivermectin is a crucial tool for safeguarding animal health, enhancing productivity, and ensuring the sustainability of the livestock industry as a whole. By using this active ingredient wisely and as part of an integrated approach, producers can continue to reap its benefits for years to come.

If you need support selecting the right ivermectin-based product to administer to your flock or herd, we’re here to help. We have over a decade of experience helping Australian producers and livestock owners – contact us to chat about the best option for you.