Highlights report small ruminants-April 2024

Lambs with congenital abnormalities caused by Schmallenberg virus

The Animal and Plant Health Agency (APHA) in Britain reported in January that the number of cases of congenital abnormalities in lambs caused by Schmallenberg virus (SBV) had increased since the end of 2023 throughout the United Kingdom. A total of 63 cases were confirmed by APHA from 1 December 2023 to 16 January 2024. In the Netherlands as well, the Veekijker has received various notifications since the beginning of 2024 of lambs with congenital abnormalities. Pathological examination has confirmed that the malformations in the submitted lambs were the result of SBV infections. The Veekijker also receives a lot of questions about the relationship between bluetongue and abnormal foetuses.

Congenital abnormalities in lambs can have various causes, both infectious and noninfectious. In some cases, a viral infection plays a part in the complex picture. It remains important to carry out pathological examinations of lambs with congenital abnormalities, in particular because viruses occur in other countries that can cause abnormalities that bear a strong resemblance to those caused by SBV. One important example is the Cache Valley virus, which not only causes malformed lambs but is also known to be a zoonosis.

The bluetongue virus is also known to cause congenital abnormalities. Unlike SBV, bluetongue infections only lead to abnormalities of the nervous system and not skeletal malformations. Whether or not abnormalities then occur in the lambs depends on the virus’s ability to pass the

placenta. Not all bluetongue viruses are capable of infecting the unborn foetus. As yet, this has primarily been described after using a live bluetongue virus. In addition, the moment during gestation at which infection occurs determines whether the lambs develop abnormalities. For bluetongue, the majority of abnormalities are observed in lambs that are infected at 50 to 100 days’ gestation.

During the bluetongue outbreak of 2006 to 2008, the effect of the bluetongue virus on the lambing period was very limited. There were no reports at that time of abortions or abnormal lambs as a result of the virus. What the situation will be with the current bluetongue serotype 3 is unknown. Pathological examinations have detected serotype 3 bluetongue virus in a small number of aborted foetuses of both cows and sheep. No congenital abnormalities were observed in the foetuses in these cases. Pathological examination can distinguish between the various causes of congenital abnormalities in lambs. Farmers and veterinarians are asked to be alert for lambs with congenital abnormalities and to contact the Veekijker if such cases occur.

Submitting foetus and afterbirth is important for abortion diagnostics

Abortion, premature birth, stillbirth and weak born lambs or kids in small ruminants is a regularly occurring problem and examining the aborted foetus and the afterbirth is the most appropriate way of making a diagnosis. If only part of the afterbirth can be collected, it is important that this piece contains the cotyledons. The placental cotyledons are the spherical structure in the afterbirth at which the exchange of nutrients and oxygen between

the mother and the foetus takes place. If there is an infectious cause, abnormalities can often be found here. Examination of foetal membranes that do not contain cotyledons is therefore less useful. If you would like to know more about how important it is to carry out abortion diagnostics and send in the foetus and the placenta, scan the QR code and listen to the podcast.

Epididymitis in the abattoir

Epididymitis is an inflammation of the epididymis and it is an important cause of infertility in rams. Bacteria such as Actinobacillis spp., Histophilus spp. and Brucella ovis are associated with this condition. Moraxella spp., Streptococcus spp., Staphylococcus spp., Actinomyces spp. and Pasteurella spp. are also sporadically involved. Many of these bacteria are commensals in the prepuce.

In December 2023, GD was approached by an abattoir manager working for the Netherlands Food and Consumer Product Safety Authority (NVWA) after they noticed a ram with unilateral purulent epididymitis on the processing line. GD provided the NVWA

with background information. Brucella ovis has not previously been detected in the Netherlands, although the clinical aspects do not allow an infection to be excluded. In the context of food safety, additional bacteriological investigations were carried out. A culture of the spleen was negative. The carcass was approved for human consumption.

Brucella melitensis and Brucella ovis are responsible worldwide for production losses resulting from reduced fertility and abortions in sheep and are therefore important pathogens in economic terms. Additionally, Brucella melitensis is a zoonosis that causes Malta fever in humans. Brucella melitensis is

monitored annually in the Netherlands. The status of the Netherlands for B. melitensis is that it is free of this bacterium. In the Netherlands, Brucella ovis is only tested for in the case of exports. Under the Animal Health Law, B. melitensis is categorised as a class B disease and B. ovis is in class D. Suspicions of brucellosis must be reported to the NVWA.

Outbreak of E. coli on a dairy goat farm

There were contacts in January between Veekijker and a veterinarian after increased losses were observed at a dairy goat farm from the end of December onwards. Based on a pathological examination of two four-year-old animals, sepsis by E. coli was diagnosed, originating in the gastrointestinal tract. Because of ongoing problems and the concomitant loss of over fifty adult animals and abortions, animals were submitted once again that also

confirmed the clinical picture of E. coli sepsis. The antibiogram of the isolates found pointed to an antibiotic-resistant strain. The search for the origin included investigating the water source (a well). A high total viable count suggested making a culture of the drinking water. The strains found were examined further by GD to see if the coliforms found in the drinking water were the same are those from the necropsies. A cluster analysis did not show clustering.

However, the problems do seem to have stopped after switching from well water to tap water.

Ovine herpes virus type 2

Ovine herpes virus type 2 (OvHV-2) is the causative agent of malignant catarrhal fever (MCF) in cattle. Sheep can carry this virus without any symptoms. The prevalence of OvHV-2 in the sheep population is thought to be high. The virus can be transmitted from sheep to cattle over short distances via aerosols. Keeping cattle and sheep together leads to an elevated risk of transmission of the virus.

Despite the cattle and sheep being accommodated separately, two cows at a dairy farm died in November as a result of

Blindness in sheep

When several sheep in the flock are blind, pinkeye – also known as infectious keratoconjunctivitis (IKC) – will quickly be suspected. The condition has a broad bacterial aetiology, with Mycoplasma conjunctivae, Chlamydia spp., Moraxella ovis, Escherichia coli, Listeria monocytogenes and Staphylococcus aureus all capable of causing this. Irritation of the cornea by dust, grass ears, straw, hairs or entropion often precedes the bacterial infection. Recurrent infections within the same flock suggest carrier status as a possibility.

Once established in the flock, the infection spreads steadily and morbidity can reach up to 100% within 4-6 weeks. Eye inflammation caused by any of these pathogens causes oedema and swelling of the cornea, which is

MCF. The clinical progress of the disease varies but almost always leads to the death of the cow. MCF can progress very rapidly or chronically. The symptoms vary depending on which organs are affected by the virus. Bloody diarrhoea and lesions of the tip of the nose, the mouth and the eyes are some of the symptoms that can occur independently of each other. Persistent high fever is virtually always present. The virus can be present but inactive in the body for a long time. This means that the incubation period can range widely, from two weeks to nine months. The disease is usually confined

to an individual animal and outbreaks are rarely observed.

Virus diagnostics are available for sheep. Tracking down carriers of the virus in complex. Virus diagnostics tend to yield negative results either because no virus is present or as false negatives due to the absence of viraemia. A negative result therefore does not rule out carrier status and the potential for transmission. Housing sheep and cattle separately is advised to reduce the risk of MCF.

very painful. The sheep become temporarily blind and photophobic. In the acute stage, an anti-inflammatory painkiller is desirable. Using antibiotics is discouraged because of the potential for inducing carrier status and because it restricts the build-up of immunity. If the inflammation is uncomplicated, recovery occurs within a few weeks. Removing animals from fields with ditches is recommended to avoid the risk of drowning, as well as to make it easier for them to access feed and water. Controlling flies is an important element in reducing transmission.

The Veekijker Kleine Herkauwers was consulted about a flock of sheep in which infectious keratoconjunctivitis occurred. Animals had a white haze on one or both eyes, blinked

Paratuberculosis in dairy goats

Paratuberculosis remains a disease to take into account in dairy goat farming. In the early months of 2024, various pathological indications of paratuberculosis infection were found in goats at several dairy goat farms. The goats arrived for pathology with case histories that listed symptoms from reduced feed intake, emaciation, wasting, loss of production, diarrhoea and nervous system symptoms through to sudden death.

On necropsy, enlarged mesenteric lymph nodes were observed with microscopic granulomatous (purulent) lymphadenitis, both with and without mineralisation. Additionally, hyperaemia, crypt abscesses and granulomatous (necrotising) inflammation of the small intestine were observed. These are typical signs of paratuberculosis, whether or not confirmed by Ziehl-Neelsen staining. It was striking

frequently and had an extensive tear streak on the side of the affected eye. The clinical picture was complicated, involving itching on the head, alopecia, thickened skin with pus foci and ventral oedema. The picture of infectious keratoconjunctivitis failed to improve in individual animals.

One sheep was sent for pathological examination at GD. The chronic changes to the eye meant that bacteriological examination could not be carried out. However, the skin exhibited severe chronic eosinophilic dermatitis, which was most likely due to scabies. The clinical progression of scabies infections can be severe and leave a heavy mark on overall immunity. In flocks with scabies infections, numerous other syndromes can often be seen as well.

that there were also concomitant problems such as gastrointestinal disorders, ruminitis with a lot of Clostridium perfringens and one case of sepsis caused by E. coli. Paratuberculosis can upset the balance in the gut so much that other secondary problems predominate. In cases of death or wasting problems with unclear causes, it is useful to eliminate paratuberculosis as an underlying condition through pathological testing.

Animal health barometer Small Ruminants

Disease/disorder/health characteristic

Articles 2.1.a and 2.1.b of the Designation of Animal Diseases in the ‘Rules for Animal Health’/Implementing Regulation (EU) 2018/1882 of the Animal Health Law (EU) 2016/429 (Category A disease)

Infectious pleuropneumonia in goats (CCPP)

(Mycoplasma capricolum subs capripneumoniae)

Never detected in the Netherlands.

Foot and Mouth Disease (FMD) Not reported in the Netherlands since 2001.

Infection with goat plague (a.k.a. PPR, peste des petits ruminants)

Infection with Rift Valley Fever virus (RVF)

Never detected in the Netherlands.

Never detected in the Netherlands.

Sheep pox and goat pox (SGP) Multiple outbreaks detected at sheep farms in Spain from September 2022 to spring of 2023. All sheep at the affected farms were culled. Never detected in the Netherlands. The calculated risk of SGP being introduced into the Netherlands is deemed small. From October 2023 onwards, multiple outbreaks have been confirmed in Greece.

Articles 2.1.a and 2.1.b of the Designation of Animal Diseases in the ‘Rules for Animal Health’/Implementing Regulation (EU) 2018/1882 of the Animal Health Law (EU) 2016/429 (Categories B to E)

Infection with Brucella abortus, B. melitensis

The required number of samples to monitor B. melitensis were tested in 2023. All results were negative and the Netherlands therefore retains its disease-free status. GD is paying extra attention to monitoring because of the BTV-3 outbreak.

Infection with the rabies virus

Infection with the bluetongue virus (serogroups 1-24)

Epididymitis in sheep (Brucella ovis)

Infection with Mycobacterium tuberculosis complex

(M. bovis, M. caprae, M. tuberculosis)

B+D+E *

Detected very rarely in bats. B+D+E

An outbreak of BTV-3 has been ongoing since September 2023. The virus causes severe problems on sheep farms and to a lesser extent on cattle and goat farms. Clinical cases of BTV-3 have been reported in Belgium and Germany. Passive monitoring in the UK has detected BTV.

Overwintering of BTV-3 is seen as a realistic possibility. Developing a safe and effective vaccine is extremely important.

There is an outbreak of BTV-8 in France leading to more clinical complaints than the outbreak that has been ongoing since 2015. C+D+E *

Examination of rams for export purposes. Not previously confirmed in NL.

The Netherlands has been officially free of bovine tuberculosis since 1999.

Disease/disorder/health characteristic

Anthrax (Bacillus anthracis)

Paratuberculosis (Mycobacterium avium subs. paratuberculosis)

Q fever (Coxiella burnetii)

Last registered outbreak in cattle in 1993. No infections detected since then.

Regular cases, largely in goats and occasionally in sheep.

The final dairy goat farm with C. burnetii was certified free from infection in 2016.

Echinococcosis An Echinococcus cyst was detected during pathological examination of a sheep in April 2023. The specific type is not known.

Trichinellosis No known cases of trichinellosis in sheep or goats.

Article 2.1.c Designation of animal diseases in the ‘Rules for Animal Health’ of the Dutch Animals Act

Transferable TSEs (scrapie, BSE)

Hardly any cases among sheep in the past ten years. In goats, the first case of scrapie was in 2000 and the last in 2001.

Article 3a.1 Notification of zoonoses under the ‘Rules for Animal Husbandry’ of the Dutch Animals Act

Campylobacteriosis (Campylobacter spp.)

Leptospirosis (Leptospira Hardjo)

Listeriose (Listeria spp.)

Salmonellosis (Salmonella spp.)

Yersiniosis (Yersinia spp.)

Toxoplasmosis (Toxoplasma gondii )

Other OIE list diseases

Enzootic abortion (Chlamydia abortus)

Caprine arthritis encephalitis (CAE)

A few cases per year. Particularly known as a cause of abortion in small ruminants.

No cases in sheep or goats for several years.

Encephalitis caused by Listeria monocytogenes is regularly found in sheep and especially in dairy goats. Problems caused by listeriosis are reported at a few dairy goat farms each year. How long listeria bacteria are excreted into the milk for is not known. Both L. monocytogenes and L. ivanovii can cause abortion in sheep and goats.

Since 2016, there have been recurrent and large-scale losses of kids at dairy goat farms, caused by a multiresistant S. Typhimurium. There also were multiple cases of illness in humans caused by the same MLVA strain of the bacterium.

A few cases per year. Identified as a cause of diarrhoea, mortality and abortion.

Only a few confirmed cases per year but probably one of the most commonly occurring causes of abortion. High seroprevalence has previously been demonstrated in sheep and goats.

One of the main causes of abortion in goats and sheep for many years. Distribution from farm to farm is through contaminated female breeding stock. Very difficult to tackle once introduced to a flock.

Commonly occurring disease in which the pathogenic virus sometimes behaves differently depending on the size of the farm. Source of introduction not always clear.

* *Further investigation is desirable into the types found in humans and animals.

* *A further study of dairy goats is underway within the framework of public-private partnership, looking at increased sustainability of dairy goat farming.

Disease/disorder/health characteristic

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Brief description

Maedi-visna virus (MVV) A significant infectious disease at sheep farms, larger ones in particular.

Tularaemia (Francisella tularensis)

Mycoplasma agalactiae

Nairobi sheep disease

Heartwater (Ehrlichia ruminantium)

Infections with Schmallenberg virus (SBV)

Since 2011, infected hares have regularly been found in the Netherlands, as well as a small number of human tularaemia patients.

Never detected in the Netherlands.

Never detected in the Netherlands.

Never detected in the Netherlands.

There have been infections with SBV every year since 2011, resulting in congenital abnormalities in lambs. There have also been various notifications in early 2024 of lambs showing congenital abnormalities caused by SBV. Excluding other possible causes of such congenital abnormalities in lambs remains important for early detection of the introduction of other viruses from the Bunyaviridae group. The UK reported elevated incidences of SBV early in 2024.

From monitoring

Abortion in small ruminants

During the early months of 2024, various infectious agents were detected that cause abortions in sheep and goats. Many causes of abortions are also zoonoses.

Milk fever in sheep Milk fever is regularly seen in sheep during mild winters. It is recommended that pregnant sheep should be given additional feed in good time.

1 Quiet: no action required or action is not expected to result in a clear improvement.

2 Increased attention: alert to an anomaly.

3 Further investigation: further investigation is ongoing or required.

Animal health monitoring

Royal GD has been responsible for animal health monitoring in the Netherlands since 2002, in close collaboration with the veterinary sectors, the business community, the Ministry of Agriculture, Nature and Food Quality, veterinarians and farmers. The information used for the surveillance programme is gathered in various ways, whereby the initiative comes in part from vets and farmers, and partly from Royal GD. This information is fully interpreted to achieve the objectives of the surveillance programme – rapid identification of health issues on the one hand and monitoring trends and developments on the other. Together, we team up for animal health, in the interests of animals, their owners and society at large.