Liver flukes closely associated with Redwater disease
In Western Canada I have steadily heard of the ever-increasing diagnosis of liver flukes. Both in clinical practise and then as a technical services veterinarian I was hearing of increasing number of herds which have a diagnosis of liver flukes. Most time it starts as an unexplained death and a complete postmortem with making many slashes through the liver will spot the adult flukes.
Veterinarians in other cases see reduced weight gains, lacklustre haircoats and diarrhea. This can be a condition which can be rather insidious to start. If you see one case, you must assume the rest of the herd has some level of infection. Death can be due to liver failure and the amount of liver damage done by the liver flukes or the association with clostridium hemolyticum or Redwater. The latter is a clostridial disease brought on by liver damage and we often see both these diseases hand-in-hand, meaning if we see Redwater we will look closer for liver flukes and vice versa. This article will review the prevalence diagnosis life cycle and very treatment of this somewhat emerging disease in Western Canada.
More positive diagnosis was more common when we had big numbers in the elk industry. It might have spread then to the wild populations of elk in some areas, although that may be just conjecture, but it does make some sense. This is another example of veterinarians working with wildlife people. We need to communicate with each other as to what is going on with the species we deal with. It has even been documented in bighorn sheep where they graze in very low land in British Columbia so covers a wide range of species.
Liver flukes are more prevalent in wetter conditions and climates as they rely on the snail as the intermediate host. Low lying areas on pasture are where the snails hang out. The general saying is if you find low land and snails, liver flukes may be in the equation and worth watching out for. In Canada primarily, I have heard of the deer fluke or giant liver fluke (fascioloides magna). Another name we rarely hear of is the common fluke fasciola hepatica. The uniqueness of the deer fluke, both in cattle, bison, bighorn sheep and other species besides the deer species, is that it is a dead-end host, meaning no further spreading of the flukes happens. The reproductive phase stops so no eggs pass out into the environment. The issue is then that there is really no reliable diagnosis until one closely examines a dead or slaughter animal and cut sections through the liver exposing the liver flukes. This helps further spread but the snails are the multipliers that get the infectious parts into the water supply.
I can’t stress enough the importance of doing autopsies on sudden deaths but also the poor-doing animals and checking all internal organs but, in these cases, especially the liver. Death from Redwater will give characteristic cartwheel shaped necrotic areas or you find the flukes themselves or abscesses from bacteria showering into the blood stream and essentially being filtered out by the liver. All these things cause varying damage to the liver and when bad enough, the liver fails. The key is, if finding one of these things, they can be to a lesser degree in the rest of the herd.
The proper diagnosis is essential for treatment for the rest of the group and prevention. Prevention will involve treating at the right time and with the appropriate medication. Once found, consider flukes endemic in an area and yearly treatment will likely be the recommended practice. Avoiding low land where snails’ habitat is great is best but likely not possible when large grazing areas are used with multiple low spots and access to water. Veterinarians find once you have it, routine treatment is necessary.
In countries such as Ireland and Scotland, you will see lots of medication for flukes in the veterinary clinics for use on cattle and sheep especially. It is a routine thing to treat. I do really hope if any evidence of flukes are found on slaughter animals that it gets communicated back to you the producer. Having a liver condemned on slaughter animals is one thing but the inciting reason or cause of the liver condemnation is what we need. Years ago, I knew of an extension veterinarian in Manitoba who gave demonstrations on cutting into the liver specifically to look for liver flukes.
In the other countries there is a lot of the common liver fluke so the common products as a flukicide are available. In Canada, treatment now involves bringing in a product that will get both types of flukes and that was triclabendazole. One trade name was “fasinex.”
The issue is, it needed to be brought in under an emergency drug release. This meant being diagnosed by your vet and getting an import permit for your herd specifically. Now most recently a company is compounding it in Canada. Your veterinarian can bring it in and have it in stock until needed and the prescription is made to your herd when dispensed. It will make it much easier to get now in Canada if it is diagnosed. Oral product is generally given by drench. Two companies, Elanco and Solvet, are the only ones now able to get this very specific treatment in Canada.
With all parasiticides we want to only use if diagnosed and prescribed by your veterinarian. The triclabendazole is in the family of benzimidazole dewormers but really specific in its effect on liver flukes. I am always hearing it is the Magna species being diagnosed in all species. The triclabendazole is given orally and mainly in the fall of the year once the immature stages of the liver flukes have been picked up from the water where the snails are. Severe infestations may require more treatment but that is where working with your veterinarian with the best treatment, timing and prevention comes into play. I know the eastern slopes of the Rockies where we see Redwater disease and a few areas of Manitoba are the prime locations in Canada but again it is diagnosed more and more by veterinarians. In cattle, where we did more postmortems on mature cows, it led to a diagnosis of flukes.
As for always preventing the Redwater, the eight-way or nine-way or 10-way clostridial vaccines should contain protection against Redwater but always ask your veterinarian to be sure. Both Redwater and liver flukes are diseases which can be controlled with the proper vaccine and timing for Redwater as well as proper control timing and treatment for liver flukes. Always get autopsies done to determine death but also as a way to evaluate parasitism, mineral status etc. Have your veterinarian do complete autopsies and if anything unusual is seen with on-farm butchering, take pictures or videos and have the situation checked out.
