Spring 2016Contents

Mycoplasma

infection in cattle 1

Haplotype Cholesterol Deficiency (HCD) in Holsteins 1

Besnoitiosis –

a disease to be

aware of 2

Why record lamb deaths? 2

Improved diagnostic testing for Tick Borne Fever 2

Dangers of livestock poisoning from garden shrubs 3

More cases of Oedema Disease in pigs 3

Investigate ill-thrift in ewes now 3

Plan ahead to reduce problems due to liver fluke next winter 4

Salmonella Isolates in Scotland 2010-2015 4

Surveillance News Animal Disease Surveillance News

This is a genetic disease first reported last year affecting Holstein cattle. Affected calves become noticeable between 3 weeks and 5 months of age. They show loss of condition and a scour that does not respond to treatment. Blood samples show low cholesterol levels. This leads to wasting and death.

The disease can only occur when two animals carrying the defective gene are mated together, this is suggestive of HCD. Genetic testing is required to prove the diagnosis. Holstein UK is producing a list of animals known to carry the genetic defect. If you have used bulls in the past that have been identified as carrier animals you should avoid carrier bulls in the future to avoid producing affected calves.

Haplotype Cholesterol Deficiency (HCD) in Holsteins

Improved methods of disease diagnosis have revealed the importance of Mycoplasma as a cause of disease in cattle. What does it mean if your vet tells you that mycoplasma are found in samples tested by the lab?

What are Mycoplasma?Mycoplasma are small bacteria. Mycoplasma bovis is the most common type associated with disease in cattle in the UK.

What problems do Mycoplasma cause?Like many other bacteria, Mycoplasma can be present in cows without causing any disease at all. When they do cause disease, it can be because the animal’s immune system is not working well, the animals’ environment is poor or because the type of Mycoplasma is very aggressive.

In cattle, the major diseases that Mycoplasma can contribute to are pneumonia and mastitis. Occasionally they can contribute to other problems too, including ear infections, eye infections and joint infections.

For example our Dumfries centre recently investigated calf problems in two dairy farms. The calves had drooping ears and watery eyes at around four weeks of age. Over time they developed facial paralysis and became unsteady on their legs. On postmortem examination the calves were found to have inner ear infections and pneumonia caused by Mycoplasma bovis.

What makes Mycoplasma difficult to diagnose and treat?Mycoplasma are difficult to grow in the laboratory. Most bacteria will grow in about 24 hours, but Mycoplasma can take up to a week.

They can also be hidden by other bacteria that grow more quickly in the lab. Modern tests, like PCR, can help with these problems, as they don’t need to wait for the bacteria to grow.

With regards to treatment, many antimicrobials are not effective against Mycoplasma. Your vet needs to identify when Mycoplasma are involved so they can prescribe an appropriate treatment.

Can I stop Mycoplasma getting into my herd?Not always, but it is a very good idea to try. Mycoplasma don’t live for long away from carrier animals, and so most spread between herds occurs by moving stock. In simple terms, the more animals you bring into your herd, the more likely you are to bring Mycoplasma in with them. Blood tests are available to help to identify possible carrier animals.

Other basic biosecurity measures, like maintaining fencing that prevents nose to nose contact at farm boundaries, will also help to reduce the risk.

Calf affected by an inner ear infection and pneumonia caused by Mycoplasma bovis.

Mycoplasma infection in cattle

Holstein calves can be affected by HCD.

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Improved diagnostic testing for Tick Borne Fever

Dangers of livestock poisoning from garden shrubs

More cases of Oedema Disease in pigs

Clinically affected pigs.

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Investigate ill-thrift in ewes now

Why record lamb deaths?Could records of lamb deaths be the key to reducing mortality in the future? Ultrasound scanning results let you know how many lambs you could have after lambing but there are always losses along the way. Can you account for the lambs that don’t survive?

SAC C VS records show that lambs failing to absorb enough antibodies from colostrum, clostridial diseases and E. coli infections such as watery mouth were the main causes of deaths in lambs less than one week of age. This is likely to be different from the picture on your farm as SAC C VS tend to receive lambs where the cause of death is not apparent on farm.

Accurate records of lamb deaths allow you to target areas where you could make improvements. Over 50% of lamb losses happen in the first 48 hours of life so concentrating on that time will have the biggest impact. An easy way to record the lambs lost is to keep a tally sheet for all the lambs that die.

This is a list of suggested categories of losses to record. You may wish to include others that are appropriate for your flock.

• Dead ewes (and the number of lambs carried)• Abortions (record the age of the ewe aborting as well as the

lambs lost)• Still born – fresh/smelly• Difficult lambing• Small weak lambs• Watery mouth• Navel ill• Joint ill• Lay on by ewe• Hypothermia/starvation• Adverse weather• Predators• Unexplained

If you find large numbers of your losses in one or two categories it would be well worth investigating these deaths. Take a few typical lambs to your closest SAC Consulting Disease Surveillance Centre or local vet for investigation. A batch price for 2-4 lambs submitted on the same is available to allow you to send a representative sample.

Monitoring losses can improve lamb survival

Most plant poisoning incidents seen by SAC C VS occur in sheep, although incidents affecting cattle and goats occur. In recent winters we have confirmed many poisoning incidents due to animals eating Pieris species (such as the garden variety, “forest flame”). Rhododendron, privet and yew also caused poisoning and deaths.

Usually we diagnose plant poisoning at post mortem examination by observing the typical pathological signs of poisoning and identifying the poisonous plants in the stomach contents. This can be challenging because the plants tend to be chewed and partially digested.

The toxic plants mentioned are not normally found growing in fields. Animals may consume the plants by grazing at field boundaries with gardens, from hedge clippings discarded into field or by the animals themselves straying into neighbouring gardens or woodland. The majority of cases seen by SAC C VS are due to animals straying, so

ensure your boundary fences are secure to prevent this potentially costly problem. The end of winter, just before spring growth starts is a high risk time for plant poisoning.

Pieris species

For many years, oedema disease was rarely diagnosed in Scottish pig herds. However over the past year that has changed and we have diagnosed the condition in several units recently.

So what is Oedema Disease? It is an acute illness of pigs usually in the first month after weaning, but occasionally in older pigs. Pigs may be found dead or showing a range of clinical signs such as dullness, wobbly gait, recumbency with paddling movements, high-pitched squealing and occasionally diarrhoea. A notable feature is puffiness of the eyelids and face. The condition is caused by toxin-producing strains of E.coli multiplying in the intestine, particularly in thriving, rapidly-growing pigs. The toxin, known as shiga-toxin, gets absorbed into the blood stream and causes damage to the lining of small blood vessels throughout the body, including the brain. Fluid leaks from the damaged vessels causing the puffiness to the face and nervous signs. Most cases prove fatal.

The disease can occur as outbreaks, affecting up to 30% of batches in some instances. There are a number of conditions that cause similar clinical signs or sudden deaths. The correct diagnosis is essential for getting effective control measures in place. Submit sudden deaths

or affected dying pigs, but remember, we need to examine the brain so pigs should not be shot as this destroys the evidence! A shiga-toxin vaccine is available and is proving effective for preventing further losses.

Is your scanning/lambing percentage lower than you expected? Have you had an increase in ewes not giving enough milk and increased lamb mortality? Have you got a high percentage of thin ewes and increased culling rate?

If yes, then it is time to investigate your problem and find out if Maedi visna (MV) is involved.

The most cost effective way to screen your flock is to have your vet take blood samples from 12 older, thinner

ewes in the flock. SAC Consulting Veterinary Services offer a discounted rate for this package.

In the past four years, almost a quarter of the commercial flocks submitting blood samples for this screening test have found positive animals. Relatively few Scottish flocks have submitted samples for testing, so many flocks could be infected without knowing. The longer the infection is present in the flock, the more difficult and more expensive it becomes to eradicate.

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Recent mild and wet winters have been ideal for the survival of the sheep tick Ixodes ricinus. As tick numbers increase so does the risk of tick borne infections.

Tick borne fever (TBF) causes a high temperature and can cause abortions in animals that have not been exposed to the infection before. It also makes animals more susceptible to other infections and can be involved in outbreaks of pneumonia , tick pyaemia and louping ill.Young lambs and older stock being moved onto affected areas for the first time are usually at the greatest risk from TBF.

Until recently the only diagnostic test available to identify tick borne fever was to look at the blood smears from

affected animals. This was time consuming and only animals with high levels of infection were likely to be identified. The Moredun Research Institute have developed a molecular test which can detect infection in blood samples and in tissues collected at post-mortem

Last year SAC C VS used this test when investigating outbreaks of pneumonia in hoggs returning to the hill after being grazed away from home over the winter. High levels of infection were found in affected hoggs. This suggests the animals either failed to develop immunity TBF before they left the farm or they had lost their immunity while away for the winter. If you farm in a tick infested area and have problems with illness in ewe hoggs when they arrive back from winter grazing , TBF could be involved.

If you find your flock is not showing evidence of infection, keep it clear by only bringing in replacement breeding stock from MV accredited flocks.

MV affected sheep

Besnoitiosis – a disease to be aware ofBesnoitiosis is a disease caused by the protozoan parasite Besnoitia besnoiti and spread by biting insects. The disease has been recognised in mainland Europe for a number of years but in July 2015 the first case was found in the Irish republic. So far the disease has not been found in the UK but could arrive at any time.

The clinical signs vary greatly. Some animals will not show obvious signs of disease but severely affected animals can die. There is currently no known treatment for the disease.

Clinical signs that may be seen in the early stages of disease• Fever and animals off food• Fluid swelling of the skin• Reddened skin around the muzzle, eye and scrotum• Reluctance to walk due to joint swelling• Swollen and inflamed testicles• Discharge from the nose and eyes• Rapid heavy breathing that could be confused with

pneumonia

In the later stages of infection the skin can become progressively thickened with hair loss. Bulls will be infertile due to effects on the testicles.Infected cattle remain carriers for life in spite of many appearing completely normally. This increases the risk that the infection could be imported in to the UK. A blood test is now available that can be used to detect carrier animals and prevent them entering the UK.

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We are pleased to have comments from readers on the usefulness of this publication and if you have topics you would like to see covered in future issues. www.sruc.ac.uk

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Plan ahead to reduce problems due to liver fluke next winterThe mild and wet conditions over the past year have led to high levels of disease due to liver fluke. As well as treating affected animals to improve productivity at the moment, you need to think ahead to reduce the potential problems for next winter.

The mud snail Galba truncatula plays an essential part in the life cycle of liver fluke as the intermediate host. If we can reduce the number of infected mud snails over the summer, the risk of disease in animals next autumn and winter is also reduced. It is important to ensure livestock do not have an adult liver fluke burden in the late spring and early summer to prevent shedding of liver fluke eggs.

Faecal samples could be collected from cattle before turnout to check for the presence of liver fluke eggs. This would check that any treatments given since housing have removed the fluke burden.

Sheep should be given a treatment in late spring/early summer which kills adult liver fluke. To avoid over use of triclabendazole one of the other drugs should be used for this treatment.

Salmonella Isolates in Scotland 2010-2015or arthritis. It can also cause a more chronic presentation, characterised by a failure to thrive, a poor hair coat and sometimes continued scouring. The wide variety of clinical presentations means that Salmonella Dublin should be considered as a possible diagnosis in batches of calves where there is high mortality, poor growth rates or high levels of disease. Adult cattle with salmonellosis can present with diarrhoea or dysentery, fever, decreased milk production or abortion. Salmonella Typhimurium can cause diarrhoea, dysentery, septicaemia and deaths in both calves and adult cattle. Speak to your veterinary practitioner if you have concerns about salmonellosis. They can advise on the submission of appropriate samples for diagnosis, treatment and control strategies. Remember salmonella can cause disease in humans.

Salmonellosis is still frequently diagnosed in cattle in Scotland. Salmonella Dublin, which is usually found in the dairy herd, is the type of salmonella most often isolated in our laboratories but Salmonella Typhimurium and other serotypes have also been diagnosed.

Figure one shows the number cases Salmonella is isolated from each year.

Figure 2 opposite shows the geographical distribution of Salmonella Dublin and Typhimurium isolates. It shows that most isolates, particularly of Salmonella Dublin, are obtained in the south-west, which is where most dairy herds are located in Scotland.

The bacteria were isolated from a variety of submission types, from carcases to foetuses and faeces. This reflects the variety of clinical presentations which can be caused by these bacteria, particularly Salmonella Dublin. In calves, it can present as sudden death, diarrhoea or dysentery (diarrhoea with blood in it), septicaemia, meningitis, pneumonia Mud snails are the intermediate host for

liver fluke.

This newsletter is circulated twice a year to livestock producers throughout Scotland to increase awareness and may give ideas for your health plans. Funded by the Scottish Government as part of its Public Good Veterinary and Advisory Services.SRUC is a charity registered in Scotland, No. SC003712

© SRUC 2016

Reports are published monthly in the Veterinary Record highlighting the disease surveillance findings in Scotland. These are available at www.sruc.ac.uk/downloads/download/992/monthly_reports_2015

Figure 1

Figure 2