Farm animal diseases and conditions

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BVD

 

Bovine Viral Diarrhoea (BVD) is a notoriously difficult disease to control. It is caused by a virus (BVDV) which principally infects cattle but which can also infect sheep and other ruminants.

Although BVDV does cause diarrhoea, the main disease occurs when BVDV infects susceptible pregnant cows in which the virus quickly crosses to the foetus.

The earlier in pregnancy that the virus reaches the foetus the more severe the disease. The most dangerous time is during the first half of pregnancy before the foetus has any immune system of its own.

If infected in the first half of pregnancy, the foetus can die and be reabsorbed, presenting as infertility or 'repeat breeding'. Other infected foetuses die later and can be aborted right up to term or be stillborn.

Some foetuses however survive to term, some are damaged and grow poorly, but many are normal. All of these animals are persistently infected (PI) with the virus which is widespread in their bodies and not recognised by their immune system as a disease.

Generalised persistent infection (PI) of the calf with BVDV can only be established during the first half of pregnancy, when the calf’s immune system is beginning to develop.

PI calves excrete virus continuously for the rest of their lives but they may develop mucosal disease (a fatal enteric disease) at any age. If a PI cow breeds successfully she will always produce a PI calf.

BVD infection is spread and maintained through the existence of PI animals, which constantly excrete the virus. They will rapidly infect other cattle that are in close contact, and may make them more susceptible to other diseases such as pneumonia.

Control and prevention of the infection can only be achieved by applying strict biosecurity procedures, vaccination and long term control strategies, particularly in identifying the PI animals and removing them.

Scotland has a Bvd eradication scheme, full details are available at https://www2.gov.scot/Topics/farmingrural/Agriculture/animal-welfare/Diseases/disease/bvd/whatsnew. The national level of exposure has dropped from 40% to 10% of herds. However Remember, as the number of herds exposed to BVD falls, natural immunity will wane, leaving the national herd very susceptible to BVD outbreaks.  It will be more critical than ever for cattle keepers to maintain their biosecurity. 

For many herds, vaccination will be important, other herds will be able to rely on physical separation of cattle, avoiding both direct and indirect contact. 

At present, most BVD outbreaks and on-going cases are caused by PIs in the same herd, but some are due to contact with PIs off-farm, e.g. neighbouring herds, shows, markets and via visitors acting as fomites.  As eradication progresses, there will be proportionately more BVD breakdowns for which the source is off-farm and difficult, or impossible, to identify.

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For advice on BVD, please get in touch with our farm vets by calling 01382 811111

Calf Pneumonia

Waiting for an outbreak to occur and treating with antibiotics is very common practice, yet is it really the best way of effectively controlling and preventing the disease?

Using antibiotics could be a more expensive option than vaccination, and may have other implications, with chronic lung damage causing great loss in performance. Fighting an outbreak of pneumonia with antibiotics or group antibiotic therapy is unpopular with the end consumer and a number of milk and beef buyers. Furthermore, when you add up all the costs, antibiotic therapy often works out more expensive than vaccination. This is a high risk strategy as permanent damage is often done before treatment can take place.

A typical course of a pneumonia vaccine will cost you in the region of £9 per head. Antibiotic treatments can cost as much as £13-£15. To this you can add the cost of keeping a sick calf on milk for approximately 14 days (£8.40), any extra labour and the cost of calling the vet out, with suckling calves losing growth and production. Very soon, an outbreak can become more expensive than that of vaccinating.

Vaccination clearly has the potential to be a much more cost effective method of managing pneumonia. It also gives peace of mind since the vaccine provides ongoing immunity.

There are a number of different vaccines available, all of which differ slightly in the types of pneumonia they can control. The disease is caused by a number of "bugs" - some viral, some bacterial. Ventilation and stress are also important considerations. In young calves, pasteurella and RSV are the main threats, while IBR tends to be more of a problem in older animals. Pasteurella is a bacteria, while RSV and IBR are both viruses.

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For advice on Pneumonia, please get in touch with our farm vets by calling 01382 811111

Calf Scour

Calf scour (diarrhoea) is a common problem encountered and there are several potential causes - bacterial, viral, protozoal and nutritional. The age of the calf affected by scour is important in determining the most likely culprit.

Calf age

1-4 days; E-coli most likely
1-3 weeks; Rotavirus, Coronavirus, Cryptosporidia
2-6 weeks; Salmonella

E-coli scour seen in very young calves is quite uncommon but when it does occur is associated with high mortality rates. Calves suffering from meningitis or septicaemia, (infection in the blood) can look similar, close examination by a vet ± confirmation of the presence of e-coli in a faecal sample is important in determining the most likely cause and therefore the correct treatment.

Calves affected by E.coli scour become dehydrated and require fluid support either by teat/stomach tube or in those very weak directly in to the vein. Antibiotics orally are also required. Where an outbreak is occurring good hygiene is paramount with the isolation of affected calves and ensuring all newborns receive adequate colostrum within the first 24 hours. Vaccinating cows still to calve will also help to reduce the occurrence by providing protection via the colostrums, (see vaccination details later).

 

In calves aged 1-3 weeks by far the most common cause is rotavirus. Confirmation can be made by taking faecal samples from 4 or more affected animals as a small number of ‘normal’ calves can test positive for rotavirus without showing any signs of disease. Severely affected calves require fluids directly in to the vein, (which usually rapidly shows a marked improvement), followed by electrolyte solutions alternated with colostrums/milk by teat or stomach tube every couple of hours. Maintaining hydration is the key to saving affected calves and as the cause is viral not bacterial antibiotics are not indicated.

Coronavirus is becoming more common and shows similar sometimes milder signs and are treated the same.

Cryptosporidia can cause scour on its own but often contributes to the severity of viral scours. There is now a specific treatment available, however keeping affected calves well hydrated is also vital.

 

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For advice on Calf Scour, please get in touch with our farm vets by calling 01382 811111

IBR

 

Causes

This infection is a serious economic problem for large livestock facilities nearly all over the word. Only a few countries are known to be free of IBR.

Often bought- in- animals are infected, but show no signs because of the virus capability to withdraw into the trigeminal ganglion. It is reactivated by stress caused e.g. through transport and new surroundings. The stressed animals start spreading virus by excretion in nasal, ocular and -in case of IPV- vaginal discharge. After only a couple of days, the entire herd may be infected.
Morbidity can go up to 100%, while mortality ranges from 2 to 12%.

 

Clinical Signs

Infection with BHV 1 may cause different clinical signs:

IBR is characterized by high fever, inflammation of the nose, which reddens and has earned IBR the name red nose disease.
There may also be serous nasal discharge, which later becomes purulent. The mucous membrane shows pin-sized white plaques and pustules.

Often animals also suffer from conjunctivitis and milk production drops. BHV 1 strains causing IBR may also cause abortion in any stage of pregnancy, usually about 3 to 8 weeks after respiratory diseases occur in herds.

IPV is another form of disease with some BHV 1 strains.Clinical signs are confined to the genital tract and recognized by inflammation of vulva and vagina. You can observe pustules on the mucous membranes and mucopurulent discharge. Frequently these symptoms are joined by temporary fertility disorders.

All signs may subside within a couple of weeks, but the infected animal remains a lifelong virus carrier. These cows start spreading the virus when reactivated by stress, infection by other agents (e.g. BVDV) or subsequent to immunosuppressive treatment.

 

Diagnosis

Diagnosis can be confirmed by isolation of the virus from nasal or conjunctival swabs combined with serological tests.

At necropsy, you will discover focal necroses in liver and kidney by dissection of aborted fetuses.

Herd diagnosis is commonly based on serological tests, such as ELISA, VNT, etc. Bulk milk may also be tested. The presence of antibodies indicates a latent infection among the herd. Stressful events may trigger a reactivation of the virus. Some countries run national eradication programs by using gE-neg. marker vaccines.

Serological tests (gE ELISA) have been designed to distinguish the type of antibodies resulting from gE deleted marker vaccines from the ones that follow natural infection. Thus vaccinated herds maintain their IBR free status in spite of seroconversion.

Enzootic bronchopneumonia, FMD, malignant catarrhal fever, BVD/MD, shipping fever pneumonia.

Prevention

  • Assure hygienic standards to prevent spreading of virus
  • Rodent control
  • Fly control
  • Disinfection
  • Optimize housing and management conditions do not Purchase BHV 1 - positive - stocks
  • Isolate new animals for at least a week and screen them for diseases
  • Improve endogenous defense mechanisms in herds at risk by immunostimulation
  • Start a vaccination program
  • Vaccinate cattle with gE deleted marker vaccine to guarantee the distinction of vaccinated and infected animals
  • Vaccinate very young calves intranasally with live vaccine
  • Revaccinate after 5 weeks
  • Booster every 6 months – or according to recommendations by your vaccine manufacturer

Speak to a Farm Vet

For advice on BVD, please get in touch with our farm vets by calling 01382 811111

Johne's Disease

 

Causes

This is a disease caused by a bacterium called Mycobacterium Avian subspecies Paratuberculosis, (MAP for short)! This disease can affect both sheep and cattle although the strains of MAP appear to be different so they may not infect each other. Many wildlife species may transmit the MAP bacteria in their faeces however so aiding spread. Symptoms are those of a severe diarrhoea, with weight-loss and there is no cure.
In the UK up to 30% of all herds are thought to be infected with Johnes.

Most animals acquire the infection as calves but don’t shown signs of the disease until they are between 3 and 5 years old, (sometimes even older). The most common way for a calf to become infected is by ingesting faeces from an infected cow eg by sucking off dirty teats or by being born in dirty calving boxes. It is also possible though for the bacteria to be present in the colostrum of the dam if she is infected or even pass to the calf whilst it is still in the womb of an infected dam.

The MAP bacterium multiplies slowly in the gut of infected animals causing it to become thickened and less able to absorb nutrients from the diet as well as leaking proteins from the blood. Classically affected animals start to show weight loss with ‘pea-soup’ diarrhoea often with bubbles in it. Any stressful event can bring on the signs of disease quicker eg calving, movement, concurrent disease and poor nutrition. Other signs that affected animals may exhibit are ‘bottle jaw’ where fluid accumulates under the chin, loss of coat pigment and reduced milk yield.

In beef herds this disease is a problem due to earlier culling of affected cows and in dairy reduced milk yields even in the early stages of disease as well as an increased culling rate. Making a diagnosis of Johnes in a cow showing signs of disease is much easier then trying to identify cows infected with MAP that are still looking healthy as the tests available are much more likely to find either the MAP organism or other signs of its presence when cows are showing signs of disease. Tests available include faecal sample, (cheap/simple), blood sample and biopsy. By taking both a faecal and blood sample we are increasing our chances of finding the organism if it is present.

 

 

Control options

1. Test and Cull

If you want Johnes free accreditation this is the only option involving testing of all breeding stock more than 24 months old, annually. Positive animals and their progeny are culled/fattened. As the tests are not perfect some infected animals will not be detected on a test, so it takes at least 2 years of finding no positives before eradication can not be proved (i.e. 3 annual tests which show the whole herd to be negative).

 

2. Control
  • Calving Hygiene clean calving boxes and sheds
  • Dairy units removal of the calf before suckling and feeding ‘clean colostrum’ ie from an older cow who has had at least 2 negative tests for Johne’s if she is in good condition and has no scour
  • Prevent faecal contamination of feed and water
  • Don’t spread slurry and muck on grazing fields
  • Cull any positive animals or those who look like they have the disease and don’t keep their offspring as breeding replacements
  • Restock only from problem free herds

 

3. Vaccination

No current UK vaccine, although a vaccine can be imported. Won’t eradicate disease but will reduce the number of clinically affected animals. The main problem is that vaccination may cause animals to be falsely positive at their TB test.

For more advice and an answer to any further questions you may have please contact one of the large animal vets here at Parkside.

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For advice on Johne's Disease, please get in touch with our farm vets by calling 01382 811111

Orf in Sheep

(Scabby Mouth)

 

Orf is a common viral condition that causes significant welfare and economic problems in UK sheep flocks. Orf can affect sheep of all ages, sexes and breeds. Animals can also carry the disease without symptoms and there is no specific treatment available.

Some flocks experience orf outbreaks year after year, whilst others have only odd cases infrequently. But often a farm that experiences only a few cases each year will suddenly get an explosive outbreak.

It is important to understand that the disease is difficult to treat effectively – and when you consider the condition can also affect humans with nasty and irritating sores the end result – then prevention of the disease taking hold in a flock is the aim.

The main financial losses from orf are associated with lambs, although ewes will often also show signs. Orf lesions in ewes are usually found on the udder and teats, and the discomfort caused means that the ewe will often not allow a lamb to suckle. As a result, lambs will try and steal milk from other ewes and this spreads infection further. When orf affects ewes in this way, consequences are both chronic and acute mastitis. Ewes suffering with chronic mastitis may lamb the following year with little or no milk due to damage to the teats, but in acute cases the ewe can lose at least half the udder or even die.

Lambs can also die from the disease, but even surviving animals never do as well as unaffected stock and their growth rates and market value can be significantly compromised.

Flocks that have never experienced orf should maintain disease-free status by carefully selecting replacements from known disease-free premises. But if orf does break out, you can control the problem with vaccination.

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For advice on ORF, please get in touch with our farm vets by calling 01382 811111

OPA in Sheep

OPA = Ovine Pulmonary Adenocarcinoma (Jaagseikte or Yaksie, or tea-pot disease, as we used to call it), is a contagious viral neoplastic disease of the lungs of sheep and rarely goats. A retro and/or herpes virus probably causes the adenomatous tumour, but work is still ongoing to determine this exactly. Often known from the Afrikaans name, Jaagsiekte.

Natural transmission is generally by the respiratory route. Close contact of individuals e.g. indoors or at feeding troughs may assist the spread of virus. The incubation period can be as long as 3-4 years, although cases are seen in much younger animals and early lesions are frequent at post-mortems of young sheep. The respiratory exudates are infectious to other sheep.

Signs of disease are only seen when the tumor is very large or numerous small tumors, (which affect respiratory function of the lungs), are present. The incidence of the disease can be up to 10% but deaths are sporadic. Although several sheep in a flock may be affected, usually a single sheep is showing clinical signs at any one time.

 

 

Clinical signs are severe respiratory distress with no coughing or fever. The affected individuals lose weight as the respiratory embarrassment increases. Clinical disease ends in death after days to weeks of signs being exhibited. OPA predisposes affected individuals to pasteurellosis so in the terminal stages some sheep have a fever and have a transient response to antibiotics. Any flock with a pasteurellosis problem could have OPA as a predisposing factor and individuals in a OPA infected flock, which develop pasteurellosis should be treated as though they are suffering from OPA until proven otherwise. Flocks with OPA have a much higher incidence of pasteurella deaths.

Diagnosis of the disease can only be done at post-mortem, as there is no serological test available at the moment. In an OPA infected flock diagnosis can be made on clinical signs – age of sheep, moist rales on auscultation of lung fields and evidence of abnormal volumes of respiratory fluids in afebrile (not running a fever) sheep. The ‘wheel-barrow test’ is a useful aid to diagnosis where by the individual sheep has its’ hind legs lifted up while its’ front feet are on the ground, thus their head is lower than their lungs, if large volumes (30-300ml) of clear mucus exudate pour from their nose and mouth then this is highly suggestive of OPA. NB. This exudate is infectious.

Treatment is not practical, controlling flocks in which the disease is known to occur must be based on reducing crowding and early elimination of any sheep that is thin, losing weight, or showing respiratory signs. Running a separate ‘clean flock’ of bought in disease free sheep until natural culling of the existing flock occurs is, in theory, the way to get a disease free flock, though breakdowns are not uncommon. At the moment there is no test to certify a sheep or flock is disease-free - and no prevention.

Speak to a Farm Vet

For advice on OPA, please get in touch with our farm vets by calling 01382 811111

Ringworm in Cattle

 

 What is Ringworm?

Scratching an itch may take just a few seconds, but when it’s a continual irritation, the time spent rubbing irritated skin can soon add up to a lot of time away from the food! The upshot is less time spent eating, leading to lower feed intakes and a check on an animal’s growth rates.

Ringworm is one of the most common causes of skin irritation for UK cattle. Affected replacement heifers can take that little bit longer to reach puberty, so age at first calving is delayed. Beef stock may finish later resulting in reduced throughput rates. 

What causes ringworm?

Ringworm, caused by a fungus that lives in hairy skin and causes cattle (and humans!) to scratch, is often accepted as a part of youngstock life, possibly because the accepted norm is that it is a self-limiting problem: in healthy animals, it stops being a problem as their immunity develops.

However, the skin lesions can take up to nine months to heal, and in very young or unthrifty stock, they can last even longer. A severe infection can also lead to follow-on skin infections, or prove attractive to flies in summer, leading to major problems.

Also, don’t forget the effect on humans of this zoonotic disease. There is a risk to staff, particularly as they come into more frequent contact with youngstock during winter housing. With labour shortages on farms it’s even more important to ensure staff health and safety. Furthermore, if the farm is open to visitors, there is a risk of the general public or schoolchildren catching ringworm.

How is it treated?

In-feed treatments for ringworm are no longer licensed for food producing animals. Currently, the best option is to vaccinate.

This is also particularly useful should adult cattle catch ringworm as it can treat affected animals. Once an animal has been fully vaccinated they are generally protected for the rest of their lives.

This live vaccine reduces clinical signs and the number of affected animals. It also shortens the recovery time for those already infected with the fungus. After the primary course, cattle continue to be protected without needing annual boosters.

But don’t forget that as the housing environment is a major source of the fungus, it’s important to thoroughly clean and disinfect housing between each batch of calves – which will also help reduce the recurrence of diarrhoea and pneumonia as well!

Speak to a Farm Vet

For advice on BVD, please get in touch with our farm vets by calling 01382 811111

Schmallenburg Virus

SCHMALLENBURG / ORTHOBUNYA VIRUS

As you have probably heard of late in the news there is much talk about this virus which was previously a tropical disease found in Australia and Japan, but has since gone on to infect Germany ( hence the name "Schmallenburg" where it was first seen in Europe), Belgium and the Netherlands, and now in just the last few weeks it has been found in the South of England on 74 farms to date across Norfolk, Sufolk, East Sussex and Kent with more cases coming to light every day.

Adult ruminants infected with the virus may experience a transient milk drop, temperature and diarrhoea or no clinical signs at all, but infection of cattle and sheep during pregnancy results in foetal malformations. Most notably the malformations seen include contraction of the limbs ( athrogryphosis), twisting of the neck/ spine (torticollis ) and swelling of the head due to large amounts of fluid filling the cerebral hemispheres of the brain (hydranencephaly). Affected newborns may appear to have neurological signs typical of "dummy" calves with blindness, paralysis and signs indicating lack of cerebral function, many may be so malformed that if they are born alive they may require to be euthanased on welfare grounds restulting in huge losses for affected farms.

The virus is thought to be spread by vectors such as culicoides midges, Mosquitos and ticks so it's spread may have occured due to climate changes that have resulted in favourable conditions for these vectors in the previous season. The condition is thought not to affect humans or other animals apart from cows and sheep.

Reports from June 2013 from SAC confirm 3 cases in Northern Scotland, around Aberdeen so it is thought that this will travel South, to us and cases in the South, will travel North towards us, so it looks like it is here to stay and will spread further via these biting insects.

If you think you may have any cases that meet the clinical signs mentioned above then please get in touch with us through our large animal office 01382 811111 and one of our large animal vets can advise you.

Speak to a Farm Vet

For advice on BVD, please get in touch with our farm vets by calling 01382 811111

bTB

Bovine Tuberculosis

Bovine tuberculosis (bTB) is an infectious disease of cattle and one of the biggest challenges facing the cattle farming industry today, particularly in the west and south west of England. It is caused by the bacterium Mycobacterium bovis (M. bovis), which can also infect and cause TB in badgers, deer, goats, pigs, camelids (llamas and alcapas), dogs and cats, as well as many other mammals, incuding man.

Scotland has been free for some years and testing the cattle herd has reduced as a result, although imported cattle into Scotland still undergo rigorous testing.

Bovine tuberculosis (bTB) is the disease in cattle that results from infection with M. bovis bacteria, and is one of the most complex animal health problems currently facing the farming industry in Great Britain. It is a notifiable disease and suspicion of the disease must be reported to your local Animal Health office.

Further information on M. bovis can be found on the Defra’s website.

Bovine TB is a chronic disease and it can take years to develop. M. bovis grows very slowly and only replicates every 12-20 hours. The lymph nodes in the animal’s head usually show infection first and as the disease progresses lesions will begin to develop on the surface of the lungs and chest cavity.

Due to the slow progression of infection, and the Government’s compulsory testing and slaughter programme clinical signs of bTB, such as weakness, coughing and loss of weight, are now rarely seen in cattle in GB. Cattle herds can be tested for bTB at least every four years which identifies most infected cattle before clinical signs of disease become apparent. This is much more frequent in areas where reactors are seen.

Look at tbhub.co.uk to see tips to reduce infection and protect you and your livestock.

Speak to a Farm Vet

For advice on BVD, please get in touch with our farm vets by calling 01382 811111