The common liver fluke (Fasciola hepatica) is a parasite of cattle that requires water and a snail host to complete its life cycle. This highly damaging parasite is primarily located in Gulf Coast states and the Pacific Northwest, where large amounts of water and snail populations are found. For cattle producers in these areas, proper timing is critical to disrupt the fluke life cycle with a liver fluke control product.

“Producers have one opportunity to truly control flukes: when the snails are dormant in the mud and cattle are infected with mostly adult flukes,” said Mark Alley, managing veterinarian with Zoetis.

For most fluke-infested areas, this means August and September are the best time to treat cattle because hot, dry weather drives snails into dormancy, thus breaking the life cycle. Flukes depend on snail hosts and cattle hosts to complete their life cycle. The key is to catch adult flukes in a cattle host before the adults begin laying eggs to contaminate the environment and the snails are dormant, cutting off continued infection with immature flukes.

“Flukicides do a poor job controlling and removing immature flukes,” Alley said. “The benefit of a product ... with albendazole as an active ingredient, is that you get control and removal of adult flukes, but it is also really effective at controlling Haemonchus contortus and Haemonchus placei, as well as Cooperia and inhibited Ostertagia ostertagi. These internal parasites can impact productivity and overall animal health.”

The economic loss caused by liver flukes in cattle is not easily quantified because infections aren’t uniform throughout a herd, and the level of infection is not easily determined. Alley pointed out that flukes migrating through the liver leave animals susceptible to clostridial diseases like black leg (Clostridium novyi) and red water disease (Clostridium haemolyticum).

“You can see the impact of liver flukes at the feedlot with the animal’s ability to process nutrients,” Alley said. “There isn’t much you can do for them at that point because the damage is already done. Liver fluke control earlier helps performance later in life.”

Alley recommended watching for the following signs or symptoms:

* Lack of appetite;

* Slower response to stimuli;

* Showing signs of pain in early infection stages, and

* Slow, steady weight loss.

If a producer suspects a liver fluke infection, Alley said they should contact a veterinarian right away. He added that once a fluke problem has been identified in a herd, it is important to continue control measures in subsequent years since conditions may continue to support the fluke life cycle. A well-planned strategic parasite control program can help protect cattle from challenges like liver flukes and support an overall healthier herd.

For more information about VALBAZEN or other parasite control products from Zoetis, contact a local Zoetis representative or herd veterinarian.

Cattle must not be slaughtered within 27 days after the last treatment with VALBAZEN. Do not use in female dairy cattle of breeding age. Do no administer to female cattle during the first 45 days of pregnancy or for 45 days after removal of bulls.