Parasite control in livestock is changing. With all anthelmintics now requiring a veterinary prescription, livestock keepers are being encouraged to move away from routine dosing and toward more targeted treatment plans.
This change comes at an important time. Unpredictable weather patterns, delayed spring turnout, and increased uncertainty about parasite risks make whole-group dosing less effective, and perhaps unnecessary.
According to Peter Howard, veterinary consultant at Boehringer Ingelheim, involving the on-farm veterinarian in parasitology planning can help protect animal performance and deworming effectiveness in the long term.
Resistance has become a real threat
For many years, many farms have relied on routine seasonal treatments, timed treatments, or whole package dosing.
But increasing levels of anthelmintic resistance mean this approach is no longer sustainable.
“We can’t expect to release new worms every few years,” Howard said.
“That’s why it’s essential that we use the products we have available today in the most responsible ways possible.”
Developing new anti-parasitic products can take more than a decade, while stricter regulations on environmental impact and food safety are making innovation more difficult.
As a result, protecting the effectiveness of existing products is now a key priority for the Irish livestock sector.
Routine dosing is less reliable
In seasons with delayed turnout, or with unusually high or low temperatures, parasite challenges may not follow normal patterns.
Grass growth, stocking rates and grazing rotation can be affected when livestock are exposed to worms.
This makes routine calendar-based dosing less reliable.
Instead, farmers are encouraged to monitor parasite burdens and treat only when animals are likely to benefit.
Correct application technique is vital. Source: Boehringer Ingelheim
“Sustainable parasite control depends on using treatments strategically rather than routinely,” Howard said.
Since 1 December 2025, all anti-parasitic medicines require a veterinary prescription, meaning that cattle, sheep and dairy farmers need to work closely with vets to get the right treatment for worms, roundworms and other parasites.
One of the simplest ways for farmers to assess worm burden is to implement a testing and monitoring system.
Testing can prevent unnecessary doses
Regular testing of faecal egg counts (FEC) in youngsters gives a clearer picture of parasite pressure on the farm.
Monitoring is especially important during the early grazing season, when parasite numbers rise rapidly.
“Initial trial centers can help guide treatment decisions, allowing animals to be identified for treatment only when parasite burdens reach levels likely to impact health and performance,” Howard explained.
Collect the number of fecal eggs in a bowl. Source: Boehringer Ingelheim
This targeted approach can avoid unnecessary treatments, helping reduce labor and drug costs, and slowing the development of resistance.
“With the guidance of your farm veterinarian, fecal egg sampling and treatment planning can be integrated into routine herd management,” Howard suggested.
“It is often better to have regular testing delivered to your local clinic, rather than having to remember to do it yourself, with all the other tasks being done.”
Correct use is equally important
Even when treatment is necessary, getting the application method correct is vital.
Under/excessive doses, poor titration or use of the wrong product can reduce effectiveness and increase the risk of developing resistance.
Using the right product at the right time, at the right dose rate, helps maximize performance while protecting the effectiveness of the anthelmintics available.
Long-term approach to parasite control
“Sustainable parasite control is not about avoiding anthelmintics altogether. It’s about using them more carefully, and only when needed,” Howard stressed.
“By working closely with your farm veterinarian, using fecal egg counts and other tests, and moving away from routine blanket dosing, ranchers can maintain animal performance while helping to maintain the effectiveness of future anthelmintics.”
Educational service provided by Boehringer Ingelheim Animal Health UK Ltd. Further information is available from Boehringer Ingelheim Animal Health UK Ltd, RG12 8YS, United Kingdom. ©2026. All rights reserved. Preparation date: May 2026. UI-RUM-0094-2026. Use medications responsibly.
