Your Reading List

Deer And Wet Bring Liver Flukes

Transportation $289.95 FLUKE DRUGS EXPENSIVE

Autopsy

EDR certificate $25 to $100

$100

Total cost $673.95 to $748.95

Extreme wet conditions we’ve had in Manitoba’s Interlake have hit us from another angle. As if the inability to make enough feed wasn’t enough, we are now faced with an increase in liver flukes. Wet conditions and the increase in the deer and elk populations have created perfect conditions for the liver flukes to multiply.

The natural host for the liver fluke is the cervid family, which consists of elk, moose, and deer, but the fluke infects cattle, sheep and goats that graze areas where deer, elk, or moose frequent. The life cycle of the liver fluke begins when eggs are shed in the feces of the deer. When deposited into warm, moist environments, the eggs develop into a larva stage called miracidium. These penetrate the shells of snails, the intermediary host, and further develop within the snail till they turn into a tadpole-like creature (cercaria), which is shed by the snail. At this point, they migrate onto vegetation and can be ingested by grazing animals. This is when the problems develop for livestock.

When an animal ingests the young fluke, the fluke proceeds to penetrate the gut wall and migrate to the liver. Once in the liver, young flukes migrate throughout the liver tissue. Eventually they become encysted within the liver.

In their natural host, the cervids, flukes mature and produce eggs. In cattle, the reaction to the unwanted guest is more intense. Cattle react to the parasite by forming an impermeable cyst around the fluke, which prevents it from releasing eggs. This makes cattle a dead end host for the fluke and it makes it impossible to run fecal tests to find the flukes in cattle. Cattle infected with liver flukes exhibit symptoms of chronic parasitism, such as weight loss, anemia and swelling under the jaw, due to a low blood protein that doesn’t correct with the use of wormers. Luckily for cattle producers, liver flukes do not often result in the death of the livestock. The major economic impact is loss of feed conversion and liver condemnation. The same is not true for sheep and goat producers.

FLUKES KILL SHEEP AND GOATS

In sheep and goats, the fluke does not become encysted. This allows flukes to migrate hither and forth within the liver, causing severe damage and eventually the death of the infected sheep or goat. Symptoms of liver fluke infection can be acute or chronic. If massive numbers of the parasite are ingested over a short time, there is tremendous injury to the liver. Symptoms are sudden distended painful abdomen, anemia, and anorexia. Death can occur in a short time.

The chronic disease is more common, with signs such as anemia, inability to gain weight, swelling under the jar area and reduced milk production. Diagnoses can be confirmed by finding fluke eggs in the feces (fecal sedimentation method) or by finding liver damage at post mortem. Adult flukes are easily seen in the bile ducts and black tracts (hemorrhagic) within the liver.

TREATMENT

Drugs available in Canada for use on flukes do not cover a full life cycle. Valbazen (Albendazole), for example, is very effective on adult flukes but doesn’t affect young ones, so if a producer has a high infection rate they would have to constantly be retreating the animals and chance the loss of many. In order to obtain the more effective drugs, Canadians must look out of country. To import veterinary drugs for personal use, the basic protocol starts with an autopsy to prove the need for the drug. This costs $25 to$100. Then the veterinarian must complete an Emergency Drug Release (EDR) form and file it with Health Canada at a $100 cost.

Once the EDR is approved, the drug is then imported. The supplier adds in the cost to transport the drug to your veterinarian. The example below is for importing a 1.5-litre container of the flukicide that kills liver flukes at all stages of development.

PREVENTION

To avoid having to import these drugs, producers should look at snail control as a prevention measure. Also, limit grazing to areas where snails are not liable to have contaminated the pasture or water bodies. If possible, segregating the livestock from wildlife is also helpful but for many of us impractical. In the Interlake the past few years, avoiding wetlands and deer pastures would be impossible. In fact, we have been finding snails on areas in pastures that wouldn’t be considered lowlands. They were deposited by overland flooding.

Another recommendation is to perform controlled spring burning of areas where snails have been found. Essentially anything you can do to interrupt the life cycle of the liver fluke will be effective in protecting your stock.

Last spring my daughter fell into a low spot and came up absolutely covered in snails, so liver flukes are a great concern for our family. Although we haven’t seen any liver damage in the animals we butchered this fall for our own use, Mamoom Rashid with Manitoba Agriculture Food and Rural Initiatives (MAFRI) assures us if we have snails and deer, we certainly can have flukes. So we will be vigilant this spring with the outlined prevention tips and hopefully we will not have to experience the pleasure of importing drugs. My fear is that by the time I would get delivery of them the animals would be dead.

Livestock groups are currently petitioning to make it easier for Canadians to access the veterinary drugs that they need for cases such as liver flukes. For more information about this, contact William F. (Bill) Paulishyn, president of Manitoba Goat Association, at [email protected]

Debbie Chikousky farms at Narcisse, Man.

Email her at [email protected]

About the author

Comments

explore

Stories from our other publications