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Bimeda UK - Items filtered by date: August 2017

A particularly warm and wet start to Summer in 2017 may result in a greater risk of liver fluke disease this Autumn meaning UK farmers must be ready to take action.

Fascioliasis is the name given to the disease caused by the Liver fluke parasite and may be caused by:

  • The migration of fluke through the liver tissue causing damage
  • The present of the adult flukes in the bile duct

Life Cycle

Adult fluke inside the bile duct lay eggs which are passed out in the faeces on to the pasture. From the moment the fluke releases the egg until it reaches the pasture can be up to 3 weeks due to the intermittent contraction of the bile duct.

Once environmental conditions are optimum the Miracidium will develop inside the egg and then hatch out. This Miracidium is only able to survive for a few hours after hatching out so must find a snail host very quickly- the mud snail.

cycle

If the Miracidium is able to find a snail host, it will bury through its muscular foot where it undergoes a further 2 stages of development and multiplies - eventually becoming the infective cercariae.

The cercariae burst out of the snail host after this period of development and migrate onto the herbage where they encyst as metacercariae. These metacercariae are hardy and can remain viable for some time.

The early immature fluke (1- 5 weeks old) tunnel through the liver tissue eventually developing into the immature fluke. The immature fluke (6-9 weeks old) continue tunnelling towards the bile duct. Eventually they reach the bile duct and if untreated at 10-12 weeks old will mature into adults, which produce eggs contaminating the pasture and continuing the life cycle.

When are Livestock Affected?

New infection occurs when the metacercariae are ingested from pasture. During very warm and wet summers this could be as early as August. In cooler, dryer summers which do not favour the mud snail there will be less metacercariae on the pasture and they will appear later.

Existing infection also known as chronic fluke disease occurs when animals are harbouring fluke which were not treated after the new infection period. These fluke are then able to complete their life cycle into adults and reside inside the bile duct producing eggs which contaminate the pasture. Chronic fluke disease is generally observed from January onwards.

Clinical Signs

In late Summer and early Autumn the risk period for acute fascioliasis begins. Acute fluke disease may result in the following:

  • Sudden death
  • Lethargy
  • ‘Dullness’
  • Reduced feed intake
  • Abdominal distension
  • Abdominal pain
  • Haemorrhage

If any stock die suddenly always get a post mortem carried out to avoid further loss.

Impact on your Stock

Fascioliasis has a significant impact not only on the welfare of your stock but also on their productivity.

Production consequences of liver fluke infection:

  • Reduced Weight Gain
  • Reduced Food Conversion Ratio
  • Drop in Milk Yield
  • Drop in fertility
  • Death

Liver fluke infection is estimated to cost UK farmers £300 million per year. 1

In sheep infection is estimated at £3-5 per animal which comprises not only of the cost of treatment but of the sub-clinical production losses such as reduced weight gain and liver condemnation. ¬¬¬2

Liver fluke is estimated to cost producers £20-25 per head of cattle3 resulting in a serious dent in profit margins.

Treatment

Liver fluke can be a challenging parasite to treat as different life stages are susceptible to different active ingredients and a reservoir of infection persists in the mud snail population and in the environment.

Most importantly, in order to protect our flukicides from the development of resistance, you must select a product which targets only the life stages you are trying to kill and dose accurately.

Your vet or SQP can advise you on the most appropriate product for your herd or flock.

Key Treatment points:

  • Use an active which targets only the life stages you are trying to kill
  • Remember that no flukicides prevent reinfection - if they are returned to the same pasture reinfection will occur immediately
  • Weigh animals and dose accurately- under-dosing increases the rate of development of resistance
Table 1: Active Ingredients licenced for Fluke Treatment in sheep and cattle
Active Ingredient Preparation Age of Fluke Killed
Sheep Cattle
Triclabendazole Oral 2 days 2 weeks
Pour-on   6 weeks +
Closantel Oral 5 weeks +  
Injectable 7 weeks + 7 weeks +
Pour-on   7 weeks +
Nitroxynil Injectable 7 weeks+ 8 weeks+
Clorsulon Injectable   Adult
Oxyclozanide Oral Adult Adult
Albendazole Oral Adult Adult

Prevention

New animals entering the farm may act as a source of infection. Ensure that you have good biosecurity protocols in place.

Chronically infected animals will contaminate the pasture when let out to grazing in Spring - check if stock are affected in Spring with a faecal sample and treat if necessary.

Environmental controls such as drainage, fencing off wet areas and moving animals from high risk pasture at key times can greatly reduce the number of metacercariae ingested and subsequently the severity of disease.

Liver fluke control should also be incorporated into your herd and flock health plans.


This editorial is provided by Bimeda- makers of Endofluke
Date editorial Prepared: August 2017
Endofluke is a POM-VPS medicine containing 100mg/ml triclabendazole.
Use medicines responsibly- Noah.co.uk/responsible
Please consult your vet or SQP to determine which is the most appropriate treatment for your flock/herd. All SPC data sheets are available on the VMD website.

References

1. Control of Worms Sustainably Liver Fluke Technical Manual

2. EBLEX (2013) Economic impact of health & welfare issues in beef cattle and sheep in England.

3. Feedback to Farmers- Controlling Liver Fluke

Published in News

Dipping ceased to be compulsory in 1992 leading to a greater incidence of sheep scab with an estimated 60-fold increase in disease on UK farms1.

In spite of having 4 medicinal active ingredients available with 16 different brands/preparations licenced and available in the UK, we are still struggling to get this disease under control.

Scab is still a major concern for UK sheep producers as it has a significant impact on the health, welfare and productivity of affected animals.

 

What is Sheep Scab?

life cycle of psoroptes ovis

Sheep scab is a disease caused by the mite Psoroptes ovis which lives on the skin surface where it feeds. The faeces produced by the sheep scab mite cause a severe allergic dermatitis resulting in the ‘scabby’ lesions which we associate with the later stages of the disease.

The mites are transferred from animal to animal by direct contact or on ‘fomites’; pieces of wool containing sheep scab mites. These mites are able to survive for 17 days without a host to feed from making it challenging to control and the potential for re-infection high.

Infestations can be debilitating, have a detrimental impact on welfare and can lead to severe economic losses. The Sheep Health and Welfare Group report 2016 states that the annual estimated cost of sheep scab in the UK is £8.3 million!2

Clinical signs include:

  • Restlessness,
  • Rubbing against fence posts,
  • Soiled/stained areas of wool,
  • Head tossing/biting,
  • Pulled wool appearance leading to eventual wool loss,
  • Open bleeding wounds and ‘scabby’ lesions,
  • Loss of condition,
  • Death


Diagnosis

First and foremost get a diagnosis from your vet. The clinical signs of lice and sheep scab infestation can be identical- particularly in the early stages.

The other complicating factor is that both diseases are contracted in the same way; through poor biosecurity. Therefore this means there is nothing to prevent animals from being dual infected with sheep scab and lice. Just because you can visualise lice it does not confirm that the animals are not also infected with sheep scab!

Your vet can perform skin scrapes on clinically affected animals or can perform blood samples to detect antibodies to infection before clinical signs become apparent.

Treatment

In the UK we have four options for controlling sheep scab (table 1). A key consideration for parasite control strategies is ensuring that we use the correct active ingredient at the correct time.

When we use dual endo- and ecto-parasiticides for sheep scab control (the macrocyclic lactones) we are targeting both internal and external parasites.

When we dip (using Diazinon) we only target external parasites.

The highest incidence of sheep scab occurs during the winter months. At this time of year gastrointestinal roundworms are generally present in lower burdens and less likely to cause disease requiring treatment than during the grazing season. To continuously expose these small burdens to anthelmintics (wormers) increases the rate of development of resistance.

SCOPS mirror this sentiment: “For the macrocyclic-lactone (clear 3-ML) wormers there has been a marked increase in recent years, probably linked to their widespread use as endectocides for the treatment of sheep scab. Action to try to preserve this group is now imperative.”3

Remember that the sheep scab mite can survive for 17 days without a host to feed from so re-infection must be controlled by using a product/protocol which provides protection for longer than this or by moving them to clean grazing/housing.

Table 1. Active Ingredients Licenced for the control of sheep scab

Group

Active Ingredient

Preparation

Notes

Organophosphate dip

Diazinon

Dip

Dipping treats and protects for up to 4 weeks

Macrocyclic Lactones

Ivermectin

Injectable

2 injections 7 days apart

Doramectin

Injectable

1 injection and move to clean area

Moxidectin 1%

Injectable

2 injections 10 days apart

Moxidectin 2%

Injectable

1 injection provides 60 days protection

Prevention

Good biosecurity is key to controlling this disease. It is impossible to tell simply by looking at animals if they have been recently exposed to Psoroptes ovis. In the early stages the disease can be asymptomatic with no visible evidence of itchy sheep. Just because the animals do not appear to be itchy and do not have pulled wool/bald patches/lesions, does not mean that they are not carrying sheep scab mites.

When purchasing new animals they should either be presumed infected and treated or an ELISA test should be utilised to assess the risk. The flock should be kept separate from other sheep at the periphery of the farm (e.g. double fencing).


About the Author
Rachel Mallet is a Veterinary Surgeon, who now works as a Professional Services Vet providing technical support to vets, SQPs and farmers in the UK. Rachel is passionate about animal health and about promoting best practice and preventative medicine amongst farmers.


Use medicines responsibly. Noah.co.uk/responsible.

Date Editorial Prepared: August 2017
Goldfleece (60.8% Diazinon) is a POM-VPS medicine.
Consult your vet or SQP before using any medicines for ectoparasite control


References:

  1. Rose H, Wall R.(2011)“Endemic sheep scab: risk factors and the behaviour of upland sheep flocks” Prev Vet Med 104 (1-2)
  2. Sheep Health & Welfare Report for Great Britain 
  3. Sustainable Control of Parasites in Sheep

 

Published in News

Nutrition in the run up to tupping is critical to ensure success. Every year farmers are spending money on various supplements for their ewes often without knowing what they actually require. To guarantee optimum nutrition you should be working with your vet to determine the current trace element status of your flock and your vet can then advise which trace elements, if any, are required. Nutrition in the run up to tupping is critical to ensure success. Every year farmers are spending money on various supplements for their ewes often without knowing what they actually require. To guarantee optimum nutrition you should be working with your vet to determine the current trace element status of your flock and your vet can then advise which trace elements, if any, are required.

Copper

Copper plays a vital role in the health and fertility of sheep. It is needed for the production of the enzymes that are required for fertility and thrive, as well as for healthy wool and white blood cell function. White blood cell function is vital to the immune system which defends the sheep against disease and parasites.

Furthermore, during gestation the ewe requires copper to develop the lamb’s nervous system. Without an adequate source of copper mid-pregnancy the lamb’s nervous system is not formed correctly and cannot be treated - this is known as swayback.

Copper should never be supplemented without first consulting a vet to establish that there is a need, as excess copper can result in copper toxicity which can prove fatal. Housed sheep, sheep which are due to be housed within the next 6 months and continental breeds and are particularly susceptible to copper toxicity.

The below table highlights how susceptible some of the UK’s most common breeds are to copper toxicity:

Highest Risk Breeds High Risk Medium Risk
North Ronaldsay Zwartbles All other breeds
Blue Faced Leciester Charollais Cheviot
Texel Suffolk/Lleyn Scottish Blackface

While copper deficiency can be caused by insufficient copper in the sheep’s diet, this is actually relatively rare. It is far more likely that sheep are ingesting adequate levels of copper, but that they are also ingesting high levels of other elements which either antagonise copper or cause harm after absorption. This includes:

  • Molybdenum
  • Sulphur
  • Iron
Cobalt

Cobalt is required by the rumen microbes for the production of Vitamin B12 which is important for thrive and fertility. Cobalt is also critical for growth in lambs.

The body has no capacity to store cobalt, therefore it must be continuously supplied. This means that a cobalt drench is not suitable to address an established cobalt deficiency. While drenches can be cheap and convenient, they are also a false economy to treat established cobalt deficiency. The excess cobalt cannot be stored and simply passes out of the animal in faeces.

Instead, a slow-release, continuous supply form of supplementation should be used, such as a bolus.

Selenium

Selenium is vital for muscle function and deficiency can result in white muscle disease. Selenium deficiency is also a cause of impaired fertility, impaired growth, poor wool quality and reduced immunity.

Iodine

Like cobalt, iodine is a trace element that ruminants have no capacity to store and a continuous supply must therefore be available. Where the animal’s diet is unable to provide this, supplementation will be required.
Where a deficiency has been identified and requires supplementation I would always advocate in favour of supplementation which supplies trace elements at a controlled and constant rate over long periods - making boluses particularly suitable.

Sheep deficient in iodine may suffer from:

  • Poor growth and weight loss
  • Reduced hormone secretion and reproductive health
  • Reduced bone growth and skeletal development

Furthermore, ewes will not be able to transfer sufficient amounts of the element to the unborn lamb. This can result in lambs being born weak or dead.

What Action Should I Take For My Flock?

Trace element status will vary from farm to farm and even from field to field!
There is no way to know which deficiencies or toxicities exist unless you carry out the diagnostics.
The best way to determine this is by blood sampling a number of the ewes and taking samples of the forage which they are consuming. Your vet can advise how many samples are required.

When Should I Take Action?

If trace elements imbalances are present in your flock you need to implement any dietary changes at least 4 weeks prior to tupping to ensure the full benefit of correcting the diet.
As such, blood sampling ewes and collection of forage samples should be carried out 6-8 weeks before tupping. This allows plenty of time to get the results back and implement any changes.

Which Product Is Right For My Flock?

If your vet diagnoses a trace element deficiency and has advised you to supplement trace elements you have a number of options including:

Oral Drenches

Drenches can seem like a cheap and convenient option. However, for trace elements which cannot be stored in the body, such as cobalt or iodine, they are not appropriate to treat deficiencies- a continuous form of supplementation must be supplied.

If you provide cobalt via a drench, the excess that the body cannot use will simply be passed out in the faeces. This means that they are in fact a false economy for the farmer. Frequent dosing is required, which increases costs to the farmer, both in terms of the drench itself and labour required.

Free Access Systems, Such as Licks and Blocks

We need to ensure that all animals receive an amount of trace elements which is compatible with their daily requirements. Too much of a trace element can prove toxic; too little and the deficiency will not be addressed.

Unfortunately, the free access lick and block systems do not provide this guarantee and an independent study highlighted that intakes between animals are extremely variable, with some consuming nothing and others consuming excessive quantities.1 In another study, 50% of ewes were shown not to consume any supplement at all.2 A more scientific approach to supplementation is required.

Injections

Injections can be suitable for targeted administration in conjunction with the advice of your vet. They can be appropriate where only a single trace element, such as copper, is required.

Pasture Dressing and Water Supplementation

Like blocks and licks, these forms of supplementation suffer from variable intakes. It is also difficult in practice for hill sheep, due to the extensive nature of hill sheep production.

In Feed Supplementation

Trace elements can be provided by the provision of TMR, concentrates or bag minerals.  Often these are specified based on ‘averages’ or ‘common requirements’ as opposed to being based on what has been determined is deficient and required on farm. Ideally these mixes should be prepared based on an investigation to address the animals’ specific trace element requirements.

This method can add significantly to the cost of production and can be difficult for hill sheep due to extensive conditions.

Trace Element Boluses

Boluses provide an convenient and controlled method of trace element supplementation. This means there are no variable intakes and no guesswork for the farmer. This is particularly important for animals requiring cobalt and iodine which cannot be stored in the body and therefore a daily supply is required. Their long-lasting nature is also highly convenient and reduces labour costs as regular bolusing is not required.

Only the Cosecure and Coseicure boluses supply rumen-available ionic copper and cobalt.  The most important thing to remember is to ensure that a need for trace element supplementation has been established before supplying any form.


Date editorial Prepared: July 2017
CoseIcure sheep bolus contains copper, cobalt and selenium and iodine.
Only provide trace element supplementation where a need to do so has been established by a vet or nutritionist. Some breeds of sheep and more susceptible to copper toxicity including blue faced Leicesters, north ronaldseys and texels.


References

  1. McDowell, 1992
  2. Kendall, 1997

About the author:
Rachel Mallet is a Veterinary Surgeon, who now works as a Professional Services Vet providing technical support to vets, SQPs and farmers in the UK. Rachel is passionate about animal health and about promoting best practice and preventative medicine amongst farmers.

Published in News