One of the first clinical signs is non-specific weight loss, which can be confused with many things. As well, having liver flukes predisposes cattle to a susceptibility to a clostridial disease (clostridium hemolyticum) better known as Redwater disease.

Producers and veterinarians need to be vigilant on watching for them. The initial diagnosis is usually made on a post-mortem exam when closely examining the liver. That is where you find the adult flukes or the characteristic necrotic areas, we get with Redwater. The liver may appear to have lumps and bumps, and on cut surface we find the flukes themselves and the inflammatory response around them.

The liver is pretty resilient but if there are lots of flukes, there is considerable damage and a poorly functioning liver. On an initial post-mortem the internal organs are checked and often the standard procedure is to make several slices through the liver. We also look for any discolouration indicating things like copper deficiency or abscesses (indicating a prior grain overload). We may even pick the flukes up in the liver on slaughter, in which case the liver is condemned but the animal may or may not have shown any clinical signs to that point. At least this alerts us to varying levels of infection that may be present with the rest of the herd.

The animal may not be showing signs of liver failure but if adult flukes are found we know they are at least a major part of the problem. There are two types of flukes in the livestock population: the common fluke and the giant fluke. They have a more complicated life cycle involving aquatic snails so are seen in wet, boggy pastures primarily. Wildlife such as the deer species can be a common source of the giant fluke and that could either be wildlife or game-farmed animals.

I hear of more cases of the giant fluke. The issue in domestic species such as cattle, bison, sheep or goats is they are a dead-end host — meaning the life cycle doesn’t perpetuate itself and so the adult flukes do not pass eggs in this species. Fecals then would not pick up any eggs and so the primary diagnosis is the post-mortem.

If you have had a problem in the past, your herd vet may go on the assumption that a fluke diagnosis is likely. In pastures identified as having flukes in the past, a management scheme would be to treat in the fall with a flukicide. Again, there is a dilemma. The albendazole dewormer has treatment for the common fluke (fasciola hepatica) listed on the label. To my knowledge though, it is pretty ineffective against the giant fluke (fasciola magna) and a product called fasinex (trichlabendazole) needs to be brought in from the U.S. as an emergency drug release as the product is not licensed in Canada.

Keep in mind wildlife are going to be the source of magna, but cattle or bison don’t spread the eggs. All these reasons are why it is critical to determine if the infection is from the giant fluke or common fluke.

When we get flukes of any kind we must always make sure the herd is vaccinated for clostridium hemolyticum. It is in some of the eight-way clostridial vaccines, but not all of them, so make sure it is on the label.

For cattle going to pasture, it is wise to clostridial vaccinate routinely. Immunity to Redwater only lasts about six months, so make sure to vaccinate on the way out to pasture. As well, keeping cattle, sheep, and goats out of boggy, wet areas will break the life cycle. That is easier said than done, and in wetter years we see an increased incidence.

Any time we find flukes it could be a serious herd problem, so treat and monitor — and keep in mind that with a product like Fasinex, there is a very long meat withdrawal period. We need to always keep that in mind whenever treating with any parasiticide — they are like antibiotics, residues remain, so a withdrawal or holding period is necessary.

In countries where it is approved, slaughter withdrawal is in excess of two months. Check with local regulators to see what is recommended in Canada as again, product must be brought in under an EDR (emergency drug release).

The good news is there is a way to treat and monitor for flukes. In other countries such as Britain, which is much wetter, cattle and especially sheep may need to be treated a few times a year with oral fluke products. Convenience with these oral products combined with good chutes are making accurate, quick oral administration easier and easier to achieve.

We can control flukes, but you first need to know they are there and then get proper treatment and put whatever preventive measures in place that you can. It is another parasite to keep our eyes on in Western Canada and can affect most species on the farm.

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The barber pole worm is nearing outbreak levels in some areas of the province, according to Manitoba Agriculture, Food and Rural Initiatives (MAFRI).

The situation on a few farms is the worst I ve seen in my time here, said Mamoon Rashid, MAFRI sheep and goat specialist. He said the parasite, along with liver flukes, is affecting sheep and goats in the some regions of the province significantly.

It s pretty much a chronic problem, but this year has been a perfect year for them, as hot weather is a perfect environment for the worm, Rashid said, adding he has seen losses to the worm occur this summer.

He noted excessive and non-strategic use of currently available dewormers has resulted in worms adapting and becoming resistant to treatment. Although the American Food and Drug Administration has recently approved a new dewormer, it has yet to reach markets, meaning the last available dewormer to hit the market was released in 1981.

The specialist noted Manitoba s frigid winters play a major role in clearing some worms during periods of -20 C and below, but the worms also have the potential to go into dormancy during these months.

Symptoms of barber pole worm include anemia and soft swelling under the jaw, Rashid said.

Liver flukes whitetail deer fluke or Fasciola magna have also been hovering at outbreak levels in the southeast part of the province, negatively impacting sheep and goats. Wet grazing areas, a certain type of snail and whitetail deer are a must for the worm cycle to complete. This particular fluke can also affect cattle, but it is fatal to sheep and goats.

When liver flukes have reached their adult stage, the infection has entered a terminal phase and will result in animal fatality if not treated, Rashid said.

He noted liver flukes cause extensive damage to the liver and have the ability to drain blood at two cc per day. They can also clog bile ducts. Infected animals shed thousands of liver fluke eggs a day, continuing the cycle of infection, while also being at risk of secondary infections such as black disease caused by clostridium novyi.

The specialist said broad-spectrum medicines such as Fasinex (trichlabendazole) can kill liver flukes at all life-cycle stages, but are not available in Canada or the U.S. However, they can be imported using an emergency drug release (EDR) application approved and filled out by a veterinarian.

Drugs like Valbazen and Ivomec Plus kill only mature liver flukes, so timing is critical, said Rashid, adding even if adult flukes are killed by these dewormers, the extensive damage they have caused can still be fatal.

Rashid noted prevention of liver flukes can be aided by avoiding wet grazing areas, controlling snail populations and keeping deer, elk and moose out of pastures.

Lucien Lesage, chairman of the Manitoba Sheep Association, says he

hasn t heard much from producers regarding

worms and flukes this year, but isn t surprised it is an issue for some regions of

the province. Last year

they were an issue too, and given

the weather this year, the conditions are right, he said.

The farmer said producers are lobbying at the federal level to obtain access to more effective drugs for the treatment of liver flukes. But so far there has not been much success.

There is no push from the pharmaceutical companies for approval either, because we re a small market, he pointed out.

However, Lesage said that the unapproved treatments still end up in the Canadian food chain because it accepts lamb for slaughter from countries where the drugs have already been approved.

shannon.vanraes@fbcpublishing.com

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“Supply cannot keep up with demand,” said Bill Paulishyn, president of the Manitoba Goat Association, “but the downside is that this liver fluke infestation is just wiping us out.”

That’s not hyperbole, said Paulishyn, who raises goats near Anola.

Liver flukes, a parasite with a complex, multi-year life cycle that passes through deer and freshwater snails, has cost him $11,000 worth of breeding bucks, nannies, and kids goats in recent years, reducing his herd to just 13 animals from 50.

The good news is that after over a year of pleading with government officials, he and the estimated 90 other goat producers in the provincial association managed to secure a streaml ined process for importing a liver fluke drench called Fasinex, which stops the parasites cold at all stages of their life cycle.

“I’ve got 13 does at home and they’re having kids now. Now I know that I can keep them alive,” he said.

The drug, already approved in seven countries including Ireland and South Africa, was previously only available via an expensive and slow process that ended up costing hundreds of dollars in regulatory fees.

“When you did get the emergency drug release form, it used to take four to six weeks, and then you had to buy it from the supplier, who wanted $230,” he said at the association’s informational booth at the Royal Manitoba Winter Fair.

“Meanwhile, you could buy it for $70 in Ireland, off the shelf.”

Previously, goat herds who went through the process and paid the money could not legally share the drug with their neighbours because permission was only granted for individual applicants.

Now, that Health Canada has streamlined the process, multiple names on the drug release form are now acceptable, and the four-to six-week waiting period has been slashed to next-day service.

A typical five-to six-centilitre oral dose is enough to treat one goat.

DEER HOSTS

Liver flukes, which typically attach themselves to the bile ducts in deer, seldom cause problems in their hosts. However, once they are ingested – typically via wet grass or sloughs where snails can be found – they may cause havoc with internal organs of sheep, alpacas, goats, llamas, bison, and cattle.

In larger ruminants, they may not kill the animal, but secondary infections may lead to “poor doers” and condemned livers at the slaughterhouse.

Infected animals may show no symptoms for months, then die suddenly in early winter due to massive internal bleeding.

Paulishyn said he suspects the liver fluke problem, which first appeared in eastern Manitoba about three to four years ago, came from Minnesota, where the whitetail deer population is exploding.

“In some areas there, they have said to the farmers there that we don’t give a damn what time of the year it is, you can shoot any deer you see,” he said.

In some parts of Manitoba, he added, especially near urban areas, restrictions on hunting have sent deer populations soaring and that could be what’s behind the burgeoning liver fluke problem.

On the plus side, the demand for chevon in Ontario and Alberta is strong. Breeding animals are currently selling north of $200 each, and butcher goats bring $1.65 to $2 per pound on the hoof.

There are about 13,000 goats in Manitoba, with plenty of room for further expansion, said Paulishyn.

Every Tuesday morning, 10 to 15 goats are slaughtered by a halal butcher at a provincially inspected plant in Carman, then shipped to a store in Winnipeg the following day.

“On Thursday, you go in to the retailer and there’s nothing left,” he said.

daniel. winters@fbcpublishing.com

———

“I’vegot13doesathomeandthey’rehavingkids now.NowIknowthatIcankeepthemalive.”

– BILL PAULISHYN

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Keep animals from grazing wet areas.

Control snail population by fencing off marshy, or wet areas.

Keep deer, elk, moose out of pastures and away from water supplies by keeping a guardian dog with the flock;

Rotate pastures.

Use a strategic control program, such as early-spring drenching with Ivomec Plus to prevent pasture contamination. A Fasinex drench in summer or early fall may be used to kill immature flukes.

Make sure new entries are fluke free by quarantining and medicating them in a separate pen for at least two weeks before letting them join the flock.

Alternate dewormers to avoid resistance.

“If the animals have picked up a lot of them in the infective stage, we should be seeing acute cases, dead animals and sudden deaths on the farm in the month of October.”

– MAMOON RASHID

Sheep producers should keep their eyes open for signs of liver fluke infestations in their flocks as the parasite is becoming more common in Manitoba.

Because the internal parasite – which resembles a small, round leech about the size of a thumbprint in its adult stage – needs a particular kind of snail to complete its life cycle, producers in areas with wet, low-lying pastures or sloughs need to be especially vigilant, according to MAFRI sheep and goat specialist Mamoon Rashid.

Sheep, cattle and goats can carry liver flukes, as well as wild ruminants such as deer, elk and moose, which are passed on through eggs in feces.

If sheep are put on pasture May 1, within as little as 20 days the eggs could be picked up by snails, the intermediate host. From there, they spend two months inside the snail, and are then deposited as eggs on pasture grasses as early as July 1.

“By then, we don’t see any animals sick or dying, but the cycle is running,” said Rashid, at the Manitoba Sheep Association AGM in Portage la Prairie March 6.

“If the animals have picked up a lot of them in the infective stage, we should be seeing acute cases, dead animals and sudden deaths on the farm in the month of October,” he said.

Animals with a low load of flukes may not show adverse signs until December, or after the immature flukes have travelled around the bloodstream. In their search for their final destination, the liver, they leave telltale signs of blackened tissues in the rumen and other organs which can be clearly seen in a post-mortem exam.

There are three types of liver fluke infestation: acute, subacute and chronic. Acute cases may occur in the form of an outbreak when pasture grasses are massively contaminated with the flukes in the larval stage. Sudden deaths due to liver hemorrhages without prior symptoms such as anemia are common in such cases.

Subacute cases mani fest symptoms of anemia due to severe internal blood loss caused by extensive liver damage.

Chronic infections are the most common type seen in Manitoba, according to Rashid.

Animals show clear signs of jaundice, or pale mucous membranes on the gums or eyelids, and death occurs after a slow loss of overall body condition which may include edema or bottle jaw.

In chronic cases, the liver flukes have reached the adult stage, and kill the animal by slowly draining its blood at a rate of up to two cc per day or clogging up the bile ducts in the liver. Infected animals in this stage can shed untold tens of thousands of liver fluke eggs.

Anemic, non-weight gaining animals are a dead giveaway for parasite infections, said Rashid, and the cause could be liver flukes or barberpole worms. Fecal egg counts can pinpoint chronic cases in both, he added.

Serological testing can be used to screen a flock, but it may not catch individuals. Slaughterhouse reports of condemned organs are another indicator.

Animals with liver flukes are at risk of a secondary infection – Black disease caused by clostridium novyi, which attacks dead tissues damaged by liver flukes. So vaccination is key.

Broad-spectrum medicines that can kill liver flukes at all life cycle stages such as Fasinex are not available in Canada or the U. S. They can only be imported from overseas via an emergency drug release (EDR) appl icat ion with Health Canada filed by a veterinarian.

Valbazen and Ivomec Plus kill only mature liver flukes, so timing is critical when using both drugs.

Ivomec Plus has a downside, however. Even if the flukes are killed by the dewormer, it doesn’t repair the damage they caused. That means the sheep themselves may have sustained severe, permanent organ damage and may not recover.

Liver flukes do not pose a food safety issue. But the production and economic losses in the form of reduced weight gains, lower lambing percentages, increased replacement costs, vet bills and condemned carcasses could push a sheep operation over the edge, said Rashid. daniel.winters@fbcpublishing.com

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