If you’re treating for liver flukes this spring, you may not be getting the most out of your deworming dollars.

Liver flukes are a devastating cattle parasite in many parts of the United States, with significant focus in the Gulf Coast, decreasing productivity, affecting reproductive health and hurting a producer’s potential profitability.1 It’s important to treat them, but it’s equally important to treat them at the right time.

“Currently available flukicides are only labeled against the adult stage of the liver fluke,” said Dr. John Davidson, senior professional services veterinarian with Boehringer Ingelheim Vetmedica, Inc. “Proper and effective treatment of the adult bovine liver fluke requires awareness of the unique parasite and its life cycle. Based on the life cycle, adults are primarily present in the late summer through late fall on the Gulf Coast of the United States.”

The liver fluke’s complex life cycle involves its larva spending a couple months in an intermediate host, a species of snail. The parasite emerges from the snail and attaches to plants in or near water sources where cattle graze. Once an animal ingests the small developing stage of the flukes, they start to destroy liver tissues and grow into adults and lay eggs. The eggs then pass through the animal in the manure and while in the environment, hatch into larva that search for snails, continuing the life cycle.

“Strategically timed administration of effective products makes the most sense,” Davidson said. “The best available science suggests that using these products at times of the year when the vulnerable adult fluke is absent doesn’t make economic sense for producers.”2

Davidson also reminds that, as with many other drugs used in veterinary medicine, proper drug selection, dosing, and timely administration are essential considerations and go a long way toward product stewardship and judicious use, which is critical to their future efficacy.

Work with your veterinarian to understand the life cycle of flukes in your area, and treat accordingly.