Todayโs path rounds are on ๐ ๐ข๐๐ง๐ญ ๐ฅ๐ข๐ฏ๐๐ซ ๐๐ฅ๐ฎ๐ค๐๐ฌ!
๐๐ก๐๐ญ ๐ข๐ฌ ๐ข๐ญ?
๐๐ข๐๐ง๐ญ ๐ฅ๐ข๐ฏ๐๐ซ ๐๐ฅ๐ฎ๐ค๐๐ฌ are a ๐ญ๐ซ๐๐ฆ๐๐ญ๐จ๐๐ (fluke) found in ๐๐๐ซ๐ฏ๐ข๐๐ฌ (deer, moose, elk) in North America. These parasites are typically found in the liver of affected animals, hence the name.
๐๐ก๐จ ๐ ๐๐ญ๐ฌ ๐ข๐ญ?
While this fluke typically affects cervids, it is more problematic in our ruminant species.
๐๐ก๐๐ญ ๐๐๐ฎ๐ฌ๐๐ฌ ๐ข๐ญ?
The giant liver flukeโs more scientific name is ๐
๐๐ฌ๐๐ข๐จ๐ฅ๐จ๐ข๐๐๐ฌ ๐ฆ๐๐ ๐ง๐, magna meaning big! These flukes can be up to 10cm in length, so this name is certainly appropriate for these guys. These flukes produce eggs that are excreted in the bile, and thus end up in the animalโs feces. The eggs then hatch into larvae who attach themselves to a ๐๐ซ๐๐ฌ๐ก๐ฐ๐๐ญ๐๐ซ ๐ฌ๐ง๐๐ข๐ฅ. The larvae develop further in the snail, and eventually leave to attach themselves to plants, which get eaten by ruminants.
The young flukes penetrate the wall of the intestine and enter into the liver. Once in their hepatic home, the flukes wander around, looking for another fluke to make eggs with. Once they find their mate, they stop wandering and a ๐๐ฒ๐ฌ๐ญ forms around them, protecting them from the immune system, and allowing them to lay eggs in peace!
๐๐ก๐ฒ ๐ข๐ฌ ๐ญ๐ก๐ข๐ฌ ๐ ๐ฉ๐ซ๐จ๐๐ฅ๐๐ฆ?
The major issue with these flukes is all that wandering they do in the liver, while they are looking for a mate. This wandering produces large, winding migration tracts through the liver that can be up to 2cm in diameter. As you can imagine, this causes extensive damage to the liver, and can even lead to liver failure. In small ruminants, even just 2 or 3 flukes can cause enough damage to kill the animal.
The flukes also arenโt very good at finding the liver, and in some cases can even end up wandering through the lungs or kidneys. This has a similar destructive effect, and can lead to compromise of those organs.
๐๐จ๐ฐ ๐ข๐ฌ ๐ข๐ญ ๐๐ข๐๐ ๐ง๐จ๐ฌ๐๐?
Unfortunately, the flukes are often unable to actually shed eggs from a ruminant host, since that isnโt the species that theyโre meant to be in. So diagnosis based on a fecal sample is very difficult. The best method of diagnosis is finding the flukes at necropsy. If you canโt find a fluke, their jet black migration tracts will give you a pretty good clue!
๐๐จ๐ฐ ๐ข๐ฌ ๐ข๐ญ ๐ญ๐ซ๐๐๐ญ๐๐? ๐๐จ๐ฐ ๐ข๐ฌ ๐ข๐ญ ๐ฉ๐ซ๐๐ฏ๐๐ง๐ญ๐๐?
Typical antiparasitics have been shown to be effective against this fluke, however prevention is always best! Keeping animals separate from cervids, and out of moist areas where snails might live, is the best method of prevention for our ruminant species.
๐๐ก๐จ๐ญ๐จ๐ฌ
1) What the flukes look like!
2-5) Examples of the jet black migration tracts through the liver. The flukes produce ๐ฉ๐จ๐ซ๐ฉ๐ก๐ฒ๐ซ๐ข๐ง as they wander around, which produces the dark colour we see at necropsy!
6) An example of migration tracts through the lung of a sheep!
๐๐จ๐ฎ๐ซ๐๐๐ฌ
Maxie, G. Jubb, Kennedy and Palmerโs Pathology of Domestic Animals, Volume 2. Sixth Edition.
Photos 1-6 ยฉ Noahโs Arkive contributors King, Acland, Wright, Harmon, Wolpert, Daoust licensed under CC BY-SA 4.0.
