Liver Fluke in Goats
Goat Parasite Information and Control
Written by Administrator-GL   
Wednesday, 01 August 2007

LIVER FLUKE


(Fasciola hepatica)

Understand the danger of Liver Fluke in goats and the damage it does!

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Adult Liver Fluke


Read our Article on effective deworming


Liver Fluke is spread by snails and slugs, so anywhere you have snails or slugs you probably have liver fluke.

The goats ingest grass with an encysted stage of the fluke present. After the goats eat this contaminated grass, the juvenile flukes "burrow" through the lining of the intestine, escape into the peritoneal cavity (the inside of the abdomen) and migrate to the liver. The flukes bore their way into the liver and over the next 6 weeks or more make their way to the interior of the liver and finally arrive in the bile ducts where they begin to lay eggs. The fluke eggs are shed into the manure of the goats. These eggs hatch and make their way to fresh water snails, which they infect and undergo additional development. They eventually emerge from the snail as young flukes and encyst (form a resistant coating) on blades of grass. When goats ingest them, the life cycle can be completed.

What damage do flukes cause?
  The young flukes cause quite a lot of damage as they migrate through the liver. If only a few flukes are migrating through the liver at one time, the damage to the goat is minimal. However, if many flukes are migrating at the same time, the damage to the liver can be extensive. In these cases, diarrhea, weight loss, and jaundice (yellow mucous membranes) can be observed. In addition to the direct damage to the liver, there is another problem liver flukes can precipitate and that is Redwater.

Each fluke can cause the loss of 0.5ml of blood per day from the liver. A moderate infestation in cattle of 100-200 fluke can lead to blood loss of up to half a litre each week, so often infected animals can be anemic.
Redwater (Bacillary Hemoglobinuria) can affect goats at any time of the year; however, it is most common in the late spring, summer, and autumn. Redwater is caused by a bacterium called Clostridium hemolyticum, which colonizes in the liver of susceptible cattle and produces protein toxins that in turn destroy the body's red blood cells, damages other organ systems and rapidly causes death. The migrating flukes damage local areas in the liver causing low oxygen tension and the bacteria prefer these conditions and begin to grow rapidly in these damaged areas. The disease has a short incubation period and the vast majority of affected goats are usually found dead and bloated.

Which drugs are effective against liver flukes?
Currently, there are only two drugs available that are effective against liver flukes in cattle. Both work best against the adult flukes, but there is some effect on the migrating juvenile flukes. Clorsulon is effective only against liver flukes and it is sold alone as Curatrem® or in combination with ivermectin as Ivomec® Plus. Thus, Curatrem® can be used to kill the flukes or Ivomec® Plus can be used to kill the flukes plus the internal parasites (worms) and external parasites (sucking lice). Additionally, albendazole (Valbazen®) has activity against flukes and internal parasites. All the drugs and combinations of drugs have advantages and disadvantages in terms of cost, ease of administration, withdrawal times, and effectiveness. Consult with your veterinarian to be certain which product will work best for your operation. Also, review with your veterinarian the time of year that will be most cost-effective for administration of drugs to kill flukes.

Another problem liver flukes seem to be associated with is decreased fertility. Studies have been published that show decreased pregnancy rates in replacement heifers and increased age to puberty in heifers infected with liver flukes. Thus, flukes can cause losses in a number of ways:


(1) direct damage to the liver, with weight loss and diarrhea, (2) death loss due to Redwater secondary to liver damage of migrating flukes, and (3) decreased reproductive performance.
How common is Redwater?

The disease is common in the western United States and the first cases were
reported in California in 1916. Most areas of California are at risk for this disease. It is
most common in areas with alkaline soils, water with a pH of 8, and in pastures that are
not well drained. The agent is often present in the feces of normal cattle and has been
isolated from the liver and kidneys of healthy cattle. Redwater is uncommon in cattle
less than one year of age. The most commonly affected cattle are adults in good
condition.

The disease has a very short incubation period and the vast majority of affected
cattle are usually found dead and bloated. If clinical signs are observed, the most
common ones are anemia, rapid breathing, high fever (104-106°F), and urine that is dark
red and foamy in appearance. The red urine is due to the presence of large amounts of
hemoglobin from the destroyed red blood cells. The affected animals are weak,
depressed and usually die within 12 hours of the time the first signs appear. Treatment is
almost always unsuccessful even if the animals are seen prior to death. The course of the
disease is very rapid and most all cattle with Redwater are simply found dead and most
bloat soon after death. Other conditions that can be confused with Redwater include (a)
Leptospirosis, (b) legume bloat, (c) copper toxicity, (d) anaplasmosis, (e) anthrax, (f)
bracken fern toxicity, and (g) blackleg. Therefore, animals that die suddenly should be
examined by your veterinarian or sent to the diagnostic laboratory to determine the cause
of death so that other losses can be prevented. Your veterinarian can easily identify
Redwater as the cause of death and can take impression smears of the liver to confirm the
condition.


Life cycle of liver fluke

The life cycle of the liver fluke is very complicated. A simplified version is shown below:


1. The adult liver fluke in the liver of its host produces eggs which pass onto the pasture
2. These eggs hatch in warm damp conditions to produce mobile larvae (miracidia) which then infect a particular species of snail
3. The larvae multiply within in the snail and develop into another swimming stage (cercaria), which emerge from the snail and settle on the pasture
4. These then develop into a highly tolerant non-mobile stage (metacercaria) that can survive for at least a year. Once eaten by the goat these hatch and migrate to the liver.

Fluke eggs do not develop significantly or hatch below 50degrees F – therefore the lifecycle of the liver fluke is mainly completed between May and October.
Liver Fluke egg


Looks very similar to the Haemonchus contortus egg


Although snails often carry infection throughout the year, two main peaks of snail infection are recognize, (summer infection and winter infection) the timing of which is dependent on climatic conditions 8.

Summer infection – snails become infected with miracidia in late spring/early summer; either from fluke eggs deposited by grazing animals in spring, or from those deposited on the pasture the previous autumn/winter. This eventually can lead to clinical disease early/mid winter.

Winter infection – As the snails become inactive during winter the development and shedding of the miracidia can no longer be completed, so they remain dormant within the snail until the following spring. This winter infection acts as a reservoir of infection for the following year.

Acute fasciolosis: late autumn/early winter
Sub acute fasciolosis: late autumn to spring
Chronic fasciolosis: winter and spring

Each adult fluke can be up to 3cm long.

Adult liver fluke can survive in goats from six months to two years.

Larval development in the snail is dependent on temperature (and rainfall); from 20 days at 30oC to 80 days at 15oC.


The complete cycle of this fluke takes 3 –4 months in ideal conditions.

Antemortem findings :

   1. Weight loss and emaciation
   2. Fall in milk production
   3. Anemia
   4. Chronic diarrhea
   5. Swelling in the mandibular area

Postmortem findings :


   1. Emaciated, anemic or edematous carcass in severe chronic infestations
   2. Presence of flukes in enlarged and thickened bile ducts and in the liver parenchyma
   3. Hepatic abscesses and secondary bacterial infection
   4. Calcification of bile ducts
   5. Black parasitic material (excrement) in the liver, lungs, diaphragm and peritoneum
   6. Black lymph nodes of the lungs and liver due to fluke excrement
   7. Icterus due to liver damage


Numerous flukes of Fasciola hepatica observed in the bile ducts and liver parenchyma ( internal anatomy of the liver) of a cow:
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Fasciola hepatica-Liver Fluke. Normal sheep liver on right, and liver damaged by migrating larvae on left.
This photo shows Chronic Liver  Disease caused by Liver Fluke:

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1Photos courtesy of FAO Animal Production and Health Papers

 

LIVER FLUKE
(an often-misidentified worm that's lethal if not treated for properly)
SYMPTOMS


Liver fluke damage is generally rather slow in appearing in mature goats... In a reasonably healthy goat, it can take years of gradual decline before the owner is even aware that Liver fluke is present. Symptoms are some, if not always all, of the following: Gradual increase in unthriftiness (dry coat, guard hairs sticking up, ribbiness, pale eye membranes (indicating anemia caused by the worm's activity), a swelling under the jaw (that has erroneously been considered among the veterinary community to be symptomatic of resistance to treatment for haemonchus contortus), and, eventually, a possibly sub-normal temp (less than 102 degrees), a distended belly (symptomatic of last-stage liver disease), and fecal pellets that are almost black in color and shriveled up with pointy ends on them.

Often the victim goat is one that has been wormed routinely, and yet still continues its gradual decline. The problem is that there's only one wormer on the market that will wipe out Liver fluke properly, Ivomec PLUS, (the PLUS part being clorsulon, specifically for eradication of Liver fluke) and many owners don't even know this wormer exists! Sadly, even when the owner finally learns about it and starts treatment, by that time there has often already been too much damage to the goat's liver for it to be saved even after proper worming.

BTW: While Liver fluke damage is often found in otherwise well-managed mature goats that despite good care continue to decline in appearance, in my experience this sudden appearance of anemia and weakness with either normal, or subnormal, temp (and sometimes swelling under the jaw as well) is not at all unusual to discover in young ruminants within the first few months of life as well. At that age it commonly shows up when they're heavily exposed to it in pastures containing wet areas, before their immune systems can get up and going to protect them. In fact, it's not uncommon for these young victims to die so fast they hardly have time to be sick.¹ This is especially true if there are any clostridial (Entero) organisms present in them, since they multiply and secrete their toxins fast in the already damaged, poorly oxygenated liver tissue .¹

TREATMENT for Liver Fluke:

I'm not one to quit without at least doing my best to save the goat... So if a goat of mine were affected with Liver Fluke I'd start it immediately on Ivomec Plus, using the appropriate worming approach as follows: All wormer packages note on the packaging that the product kills off ONLY the adult stages. So in order to get the worm load in the host down to a low enough level so that the immune system can take over and keep the problem under control, you need to worm 3X, with 10 days between wormings. The first dose will wipe out the adults already in there, the second dose will wipe out the larvae that were in the gut, but not affected by the first worming, as they become adults (but before they can start laying eggs of their own), and the third dose kills off any eggs that were left over after you started the worming regimen,when they've passed thru the larval stage, when they, too, have become adults.

And as soon as you've begun the repair process by giving the first dose of Ivomec Plus, the next step would be to immediately start the goat on subcutaneous injections of Ferrodex 200 (each 1 ml dose of which delivers 200 mg of elemental iron... BTW: If the Ferrodex 200 isn't easily accessible, go to the local Rite Aid or other drug store and buy a bottle of Iron tablets (Ferrous Sulfate, ~321% or 65mg, crush them, and feed with yogurt) (1 Ferrous Sulfate tablet is equivalent to 1/3/ dose of Ferrodex200, so 3 iron tablets would be the equivalent of 1 daily dose provided in Ferrodex200) , to restore the liver's red cells, the loss of which was the cause of have caused the anemia and the blackened, shriveled, pointy-ended fecal pellets. And at this very critical time, as adjunct (supportive) therapy, I'd give it subcutaneous doses daily of 'Fortified' B-complex' (a combination of B vitamins needed for proper body function that has everything but B-12), essential because every time the patient urinates, it's losing all of those vitamins that are needed to maintenance of its body functions, and BoSe (to support his stressed immune system so that the goat can help itself to get well from inside, while I work on it from the outside), and Banamine (to reduce the goat's pain and cut the inflammation caused by the worm damage) which, once given, will encourage the goat to want to eat once again! And last but not least, I'd give the goat a preventative doe of C&D antitoxin (to prevent entero from taking this opportunity to sneak in and finish the poor victim off because while it's down its stomach is not digesting food and moving it out of its body as it should.)

BACKGROUND :

Liver fluke is found in most of the US, but it's especially common in the Southern states due to the lack of good frosts to wipe out eggs and larvae in winter. We see it often up here in the Northern states as well, but because we have colder winters, the numbers, fortunately, are somewhat lower. However during the rainy season, no matter what part of the country the goat lives in, the Liver Fluke problem becomes particularly pervasive each year!

Today, by far the most difficult problem that we as owners face with Liver fluke treatment/control is that the veterinary community in general isn't even aware that it's there. As a result, they're unable to recommend proper treatment for it. This is because the egg of the Liver fluke (Fasciola hepatica)² looks so similar to that of the Barberpole worm (Haemonchus contortus)² that when it shows up on the slide in the Vet's office it's routinely misidentified to BE that of the Haemonchus contortus (or perhaps by some general term like strongyles, stomach worms, et al). And this is despite the fact that the Merck Veterinary Manual (8th Ed. Pp.197-198)³, which, BTW, is not a text used in Vet Schools, but in fact is instead a text available to Vetinarians and Goat owners as well, in discussing its prevelance, notes: "Fasciola hepatic, the most important trematode of domestic ruminants, is the common cause of Liver Fluke disease in the USA and other temperate areas of the world. It's endemic along the Gulf Coast, the West Coast, the Rocky Mountain Region, and other areas... IT is present in Eastern Canada, British Columbia, and South America... etc and so forth.. They have even found it in Europe, Australia,in NEw Zealand, Africa and Asia, and it's been reported in Hawaii as well"...

Until just a few years ago the veterinarian, seeing what was thought to be Haemonchus contortus eggs on the slide, would recommend Ivomec to the owner as the wormer of choice to eradicate it. And rightly so, because the moment Ivomec appeared on the scene back in the early 1980's, it was recognized as the most effective general wormer to show up ever! And frankly it remains, in my view, still the best and most efficacious general wormer on the market today.

And largely because the real Haemonchus contortus has always responded very well to Ivomec, veterinarians, misidentifying Liver fluke eggs as those of Haemonchus contortus, quite logically continued recommending Ivomec for treatment. When the Liver fluke failed to respond to the Ivomec treatment, unfortunately the loss of the animal in question was assumed to be a sign of the Haemonchus contortus having developed 'resistance' to the Ivomec! This notion has now become so pervasive that the veterinary community in general believes these days that the worms affecting livestock have developed a resistance to Ivomec, the result being a recommendation to their clients that they (1) increase the doses, and (2) turn to other wormers. Neither approach has even slowed down the deaths being caused, in fact, by Liver fluke. Since neither of those suggestions are working, the most recent approach has been to set up Famacha classes to instruct owners and veterinarians alike in how to check the eyelids of the downed animals to see if they're anemic. If the animals have pale eyelids, indicating they're anemic, owners are sometimes advised to destroy the victim, fearing that if it lives, the 'resistance to wormers' will spread even further.

Sadly, neither plain Ivomec, nor Panacur, nor any of the other general wormers on the market today, are effective against Liver fluke. The fact is, this parasite can ONLY be eradicated efficiently by using a product called Ivomec Plus (OR Valbazen Oral Suspension) . It's not the Ivomec itself, but the PLUS part of the combined wormer, which is actually 'clorsulon' , that effectively wipes out Liver fluke. And (very critically) since it only kills the ADULT of the species, clorsulon (just as all wormers) has to be used at regular doses, 3 X in a row, 10 days apart, to kill it off completely. ¹

And it will no doubt be of particular interest for those owners who are worried about using milk from does being treated with Ivomec Plus that the Pharmaceutical companies have now run the required tests on those two products that officially clears them for use in lactating ruminants!

So in my view, these days (particularly if the reader is having a hard time controlling internal parasites in his/her animals) Ivomec Plus (instead of plain Ivomec) should ALWAYS be used for general worming, 'just in case'! Just like regular Ivomec,Although it can be given orally  it's actually an injectable and for the most effective control (especially in severely wormy goats) should be injected SQ. But since right now Ivomec itself is less readily being used by people (most of whom have never even heard of Liver fluke, and many of whom have their vets ID their goats' fecal samples as well) Ivomec Plus, while its importance is gradually growing among goat owners, may not yet be available in your local feed store... However it is readily available in livestock catalogs, and online as well, at about the same price as Ivomec.


¹ Georgi's Parasitology for Veterinarians, Dwight Bowman, 7th Ed. P116.
² Veterinary Clinical Parasitology, Sloss & Kemp, 5th Ed. P.41, Fasciola hepatica eggs; P.46, Haemonchus contortus eggs
³ Merck Veterinary Manual, (8th Ed. Pp.197-198) Next for Red Water and Liver FLuke UCD VET VIEWS
CALIFORNIA CATTLEMEN’S MAGAZINE
MARCH 2003

Liver Flukes and Redwater: What’s the Connection?

Most of us in California have seen liver flukes in cattle. Most of us vaccinate our cattle at least once a year to prevent Redwater. I have had a number of questions recently about both of these cattle health problems, so I thought I would spend a little time this month discussing the connection between the two and answering some of the common questions about prevention of problems due to flukes and Redwater.

Where do liver flukes come from?

The flukes are on the grass the cattle eat! As odd as this sounds, that is what happens. The common liver fluke of cattle, Fasciola hepatica, does have a strange life cycle. The cattle eat grass with an encysted stage of the fluke present. After the cattle eat this contaminated grass, the juvenile flukes “burrow” through the lining of the intestine, escape into the peritoneal cavity (the inside cavity of the abdomen) and migrate to the liver. The flukes bore their way into the liver and over the next 6 weeks or more make their way to the interior of the liver and finally arrive in the bile ducts where they begin to lay eggs. The fluke eggs are shed into the manure of the cattle. These eggs hatch and make their way to fresh water snails. They infect the snails (burrow into the snail’s body) and undergo additional development. Eventually the young flukes emerge from the snails and encyst (form a resistant coating) on the blades of grass. When cattle ingest the grass with the fluke cysts, the life cycle is completed.

What damage do the liver flukes cause?

The young flukes can cause quite a lot of damage as they migrate through the liver. If only a few flukes are migrating through the liver at one time, the damage to the cattle is minimal. However, if many flukes are migrating at the same time, the damage to the liver can be extensive. In these cases, diarrhea, weight loss, and jaundice (yellow mucous membranes) can be observed. Another problem liver flukes seem to cause is decreased fertility. Studies have been published that show decreased pregnancy rates in replacement heifers and increased age to puberty in heifers infected with liver flukes. Thus, flukes can directly cause losses by (1) damage to the liver, with weight loss and diarrhea, and (2) decreased reproductive performance.

What causes Redwater?

Redwater is caused by a bacterium called Clostridium hemolyticum, which colonizes in the liver of susceptible cattle and produces protein toxins that in turn destroy the body's red blood cells, damages other organ systems and rapidly causes death. Migrating liver flukes damage small areas in the liver and cause low oxygen tension and these bacteria prefer these conditions and begin to grow rapidly in these damaged areas.
The disease has a short incubation period and the vast majority of affected cattle are usually found dead and bloated. This is the connection between liver flukes and Redwater—the migrating flukes damage the liver and the Redwater bacterium grows in these damaged areas and causes disease.

How common is Redwater?

The disease is common in the western United States and the first cases were reported in California in 1916. Most areas of California are at risk for this disease. It is most common in areas with alkaline soils, water with a pH of 8, and in pastures that are not well drained. The agent is often present in the feces of normal cattle and has been isolated from the liver and kidneys of healthy cattle. Redwater is uncommon in cattle less than one year of age. The most commonly affected cattle are adults in good condition.
The disease has a very short incubation period and the vast majority of affected cattle are usually found dead and bloated. If clinical signs are observed, the most common ones are anemia, rapid breathing, high fever (104-106°F), and urine that is dark red and foamy in appearance. The red urine is due to the presence of large amounts of hemoglobin from the destroyed red blood cells. The affected animals are weak, depressed and usually die within 12 hours of the time the first signs appear.
Treatment is almost always unsuccessful even if the animals are seen prior to death. The course of the disease is very rapid and most all cattle with Redwater are simply found dead and most bloat soon after death.

Other conditions that can be confused with Redwater include (a) Leptospirosis, (b) legume bloat, (c) copper toxicity, (d) anaplasmosis, (e) anthrax, (f) bracken fern toxicity, and (g) blackleg.
Therefore, animals that die suddenly should be examined by your veterinarian or sent to the diagnostic laboratory to determine the cause of death so that other losses can be prevented. Your veterinarian can easily identify Redwater as the cause of death and can take impression smears of the liver to confirm the condition.

What can I do to minimize fluke damage?

Our best option is the use of drugs to kill the flukes during strategic times of the year. The timing is dependent on the individual ranch. Killing the adult flukes that are residing in the liver of cattle before turning them onto clean pastures seems to be the most cost-effective strategy. This not only kills the flukes; but it prevents further shedding of eggs onto the pastures. Maximum transmission of flukes occurs in spring and summer in warmer regions and late summer to fall in cooler regions. Depending on your pasture rotation schedule, the use of drugs to kill flukes in the fall and/or late winter to spring should be considered.

Currently, there are two drugs available that are effective against liver flukes in cattle. Both work best against the adult flukes, but there is some effect on the migrating juvenile flukes. Clorsulon is effective only against liver flukes and it is sold alone as Curatrem® or in combination with ivermectin as Ivomec® Plus. Thus, Curatrem® can be used to kill the flukes or Ivomec® Plus can be used to kill the flukes plus the internal parasites (worms) and external parasites (sucking lice).
Additionally, albendazole (Valbazen®) has activity against flukes and internal parasites.

How can I prevent Redwater?

The most important means of prevention is the routine use of Redwater vaccines (bacterins) to increase the immunity of the cattle. Animals should be vaccinated at least once per year in areas where the disease occurs. An excellent time for boosters is in the late spring or early summer, ahead of the time of year when this disease is most common. The vaccines used to prevent Redwater do not provide long-term protection and exposure to a large number of organisms seems to override the protection provided by a single yearly booster. In areas of high exposure cattle may have to be vaccinated every 6 months or in some instances more often.
Your veterinarian can give you excellent advise about the vaccine frequency that works best in your locale. Also, it is very important that all animals that die suddenly be examined to determine the cause of death as Redwater is so common and can easily be confused with other conditions. The Redwater vaccine is made separately or is combined in "8-way Clostridial vaccines". The combination Clostridial vaccines, "5-way or 8way", should not be confused with 8-way respiratory vaccines that contain virus antigens and Leptospirosis vaccines. Also your veterinarian can advise you regarding the best drugs and appropriate time of administration to control liver flukes in your cattle.
John Maas, DVM, MS
Diplomate, ACVN & ACVIM
Extension Veterinarian
School of Veterinary Medicine
University of California-Davis
Last Updated ( Thursday, 17 November 2011 )