Ask the Vet
Liver Flukes Problem Is on the Rise
READER: A neighbor of ours fed out a steer, and at slaughter, the liver was badly infected with liver flukes. I have never heard of that in our area, and I don't know anything about them. Do I need to be worried? What do I need to do to protect my cattle?
DR. McMILLAN: Liver flukes were once considered to be a parasite of the Gulf Coast and the Pacific Northwest. But, with the increased cattle movement across the country and warmer weather, flukes are rapidly expanding their range.
Flukes have a unique life cycle. The adult flukes live in the liver and lay eggs that are passed out in the manure. They require water to complete their life cycle. In really dry conditions, the eggs can live up to a year, but if enough moisture is present, the eggs hatch into larvae (miracidia) and swim off in search of the common mud snail. They enter the snail and, after a period of time, produce another larval stage parasite (cercaria) that swims to vegetation and attaches as the encysted larval stage parasite (metacercaria). Cattle are infected when they eat infected grass or drink infected water. Inside the intestines of the cow, juvenile flukes are released and begin a migration to the liver.
The adult fluke is about the size of a large thumbnail. They have a sharp, spiny exoskeleton and migrate through the liver and bile duct, causing severe damage. Common signs can include poor body condition, anemia, bottle jaw, diarrhea, reduced milk yields and fertility, weak calves and even death. Condemned livers are a major loss for feedlots, but the largest loss may be on the farm in lost production.
Unfortunately, the signs are similar to other internal parasites, but most dewormers are not effective on flukes. So, diagnosis of fluke infection is very important.
Many times, fluke infection is found at necropsy or at slaughter. Your veterinarian can diagnose fluke infection by finding fluke eggs on a fecal sedimentation test. There are also blood tests to check for antibodies to flukes. Ultrasound can be used to find liver damage, and the liver can also be biopsied.
Treatment of flukes can be challenging since there is no product approved in the U.S. that kills the juvenile stages, which cause much of the damage. Timing of deworming is critical since the earliest we can start killing the parasite is eight to 12 weeks after infection. Consider Albendazole (Valbazen) drench and products containing clorsulon (Ivomec Plus and generics). Check with your veterinarian on when and how often to deworm, and which product is best for your operation.
Other management steps are also critical. Since there is no way to effectively kill snails, keep cattle off wet areas or improve drainage to avoid standing water, which will reduce exposure to the snail habitat.
Unfortunately, if you do not have flukes in your area, they may be headed your way soon, so be on the lookout.
READER: We just had a dog die from parvo. Is there anything you can do if a dog gets parvo?
DR. McMILLAN: Canine parvoviral enteritis is a disease that emerged worldwide in 1978. Most experts believe it was a mutation of the virus that causes feline panleukopenia. Since dogs had no natural immunity to it, the disease spread rapidly, producing severe and often deadly results. Over the years, with improved vaccine technology, the disease has become almost entirely preventable with a professionally designed and administered puppy health program.
Most cases of parvo are treatable. Treatment focuses on maintaining hydration and electrolyte balance with intravenous fluids and medications to stop vomiting, protect the gastrointestinal tract and relieve pain. Antibiotics are given to prevent secondary bacterial infections but have no effect on the virus. Until recently, there was nothing that could be done for the virus, but recently, a monoclonal antibody has been approved that targets the virus. Initial results have been impressive.
Treatment of parvo is expensive, and some dogs may die even with aggressive treatment. Prevention of this and many other diseases is easy and much more cost-effective. We recommend starting a vaccine series beginning at 6 weeks of age and giving boosters every three weeks until the puppy is at least 15 weeks of age. We check puppies for internal and external parasites, and deworm them. We also start them on heartworm and flea and tick preventives as soon as possible. With this program, I can't remember the last puppy we had that broke with disease, so please take your puppies to your veterinarian.
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-- Please contact your veterinarian with questions pertaining to the health of your herd. Every operation is unique, and the information in this column does not pertain to all situations. This is not intended as medical advice but is purely for informational purposes.
-- These are only my thoughts and general guidelines. Please get with your veterinarian and together develop the best program for your herd.
-- Email Dr. Ken McMillan at vet@dtn.com
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