Veterinary RecordVolume 189, Issue 2 p. 61-65 SurveillanceFree Access Schmallenberg virus infection suspected in a calf born to an imported heifer First published: 23 July 2021 https://doi.org/10.1002/vetr.749AboutSectionsPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onEmailFacebookTwitterLinked InRedditWechat THE mean temperature in Scotland in May was 1.2°C below the long-term average, with more frosts than usual. Scotland as a whole had 130 per cent of average rainfall, with more than double the average in some eastern parts but below average in the west. Sunshine totals were 80 per cent of average. Cattle Nutritional and metabolic disorders A six-year-old Ayrshire cow became anorexic with milk drop and malaise three weeks after calving. A ketotic smell was noted and blood calcium and phosphorous levels were low, but there was little response to treatment with corticosteroids, multivitamins, calcium and phosphorous. After being relatively stable for a week the cow then deteriorated rapidly and died. Externally the cow did not appear excessively fat but postmortem examination revealed a large amount of intra-abdominal fat. The liver was swollen, greasy and pale with petechial haemorrhages on the serosa. Sections of tissue floated in water and the findings overall were consistent with a diagnosis of severe hepatic lipidosis. A vitreous humour beta-hydroxybutyrate result of 10.7 mmol/l confirmed significant acetonaemia. ABOUT THIS REPORT This monthly summary is produced for Vet Record by Scotland's Rural College Veterinary Services (SRUC VS) and is based on reports from its surveillance centres in Edinburgh, Perth, St Boswells, Ayr (Auchincruive), Dumfries, Aberdeen, Inverness and Thurso and in collaboration with the Moredun Research Institute and the University of Glasgow School of Veterinary Medicine. SRUC VS monthly reports are available online at www.sruc.ac.uk/downloads/120613/monthly_reports from the first of every month. SRUC VS DISEASE SURVEILLANCE HEADLINES, MAY 2021 Arthrogryposis and torticollis consistent with in-utero Schmallenberg virus infection in a calf born to an imported heifer Congenital goitre and alopecia in a salers calf Swaledale encephalopathy in lambs from five flocks “Findings were consistent with severe hepatic lipidosis A 25 × 12 cm diameter firm mass with a necrotic centre was detected within the fat adjacent to the pylorus. This was restricting pyloric outflow and was the likely cause of the anorexia. Histopathology confirmed that the mass was an area of fat necrosis. Parasitic diseases A group of 10 beef heifers at grass that were in poor condition after winter were reported to be losing weight and two developed profuse watery diarrhoea. Blood samples were submitted and pepsinogen results of 4.9 and 3.5 iu/l (reference range <1.5 iu/l) were consistent with a diagnosis of abomasal parasitism due to ostertagiosis. Generalised and systemic conditions A three-year-old suckler cow was submitted for investigation of sudden deaths associated with one field. Three cattle had been found dead in the month since turnout and several sheep and a donkey had also died. Inspection of the field failed to detect any potential source of toxins. The carcase was markedly autolysed despite being examined within 12 hours of death. Chemosis and vulval oedema were noted and two pale firm areas surrounded by a zone of haemorrhage were found in the liver. A fluorescent antibody test on tissue from the liver lesion proved positive for Clostridium novyi confirming a diagnosis of black disease. Clostridial vaccination and the postmortem examination of any further animals to die in this field were advised. A 10-week-old suckled calf was treated for diarrhoea but became recumbent and died. On-farm postmortem examination detected haemorrhagic intestinal contents, oedematous intestines and enlarged lymph nodes. Only 50 coccidial oocysts per gram were detected in caecal contents; however, histopathology of the large intestine identified a chronic and severe typhlocolitis with entrapped coccidial oocysts consistent with a diagnosis of coccidiosis. Prominent perivascular aggregations of lymphocytes were detected in the renal cortex, lung and brain raising the suspicion of malignant catarrhal fever. This was confirmed by PCR detection of ovine herpesvirus 2 DNA in kidney tissue. The calf had been housed since birth and, as this period coincided with lambing time, periparturient ewes were considered to be a potential source of infection. Alimentary tract disorders A one-week-old suckled calf became lethargic and died one week later after failing to respond to treatment with antibiotics, vitamins and corticosteroids. Small nodular lesions overlying ulcers were found in the distal oesophagus. The rumen contained grey liquid digesta with a pH of 4.4, and areas of ulceration were present on both the rumen and abomasal mucosae (Fig 1). Fig 1Open in figure viewerPowerPoint Fungal abomasitis in a 10-day-old suckled calf Histopathology confirmed a fungal rumenitis and abomasitis and Candida albicans was cultured from the oesophagus. The dam was described as highly strung and a zinc sulfate turbidity test result of 3 units (reference range >20 units) indicated a failure of maternal colostral antibody transfer. The primary problem was not clear in this case. Ruminal acidosis secondary to rumen drinking will predispose to fungal infection; however, fungal infection secondary to antimicrobial therapy would be an alternative explanation. The lesions will have impaired the functioning of the oesophageal groove, perpetuating rumen drinking and ensuring a terminal outcome. Reproductive tract conditions A dairy farm imported 12 heifers from Germany in mid-April. One month later an assisted calving produced a calf with clinical signs of torticollis and arthrogryposis. An on-farm postmortem examination was performed and samples were submitted to SRUC VS. Seroconversion to Schmallenberg virus (SBV) was demonstrated in the dam. Histopathology of the calf brain and spinal cord identified micromyelia with a marked reduction in the number of ventral horn neurones and multifocal absence of ependyma, including within the mesencephalic aqueduct, with gliosis in the subventricular neuroparenchyma. These lesions are typical of the consequences of in-utero teratogenic orthobunyaviral (Schmallenberg) infection towards the end of the risk period of 30 to 150 days gestation. SBV RNA was not detected in the unfixed central nervous system (cerebellar) sample submitted but this does not preclude the diagnosis.1 The dam of the affected calf would likely have been infected with SBV between September 2020 and January 2021 and would not have been viraemic at the time of importation. In addition, April was considered to fall within the vector-free period with lower than average temperatures. Overall the importation of these heifers was considered to represent a negligible risk of introducing SBV to the area. Screening of blood samples from the remainder of the imported group revealed the presence of antibodies to SBV in a further two animals, one of which originated from the same holding as the dam of the deformed calf. Musculoskeletal conditions A dairy herd reported ongoing issues with lameness in four- to six-week-old calves most of which recovered after a prolonged course of antibiotics. The herd had a history of Mycoplasma bovis infection and there had been a recent increase in pneumonia cases. A six-week-old Aberdeen Angus-cross bull calf was euthanased for investigation of the problem. It had been lame for three days and treated only with non-steroidal anti-inflammatory drugs. Septic arthritis was confirmed in the left shoulder (Fig 2) along with evidence of pneumonia. A pure growth of Streptococcus ruminantium (previously Streptococcus suis serotype 33) was isolated from the joint. This has been reported as a cause of septic arthritis in calves and has also been isolated from cases of pneumonia and endocarditis.2 Fig 2Open in figure viewerPowerPoint Septic arthritis due to Streptococcus ruminantium in a six-week-old calf PERFORATED ABOMASAL ULCERS IN SUCKLED CALVES SRUC VS recorded 102 diagnoses of perforated abomasal ulcers in suckled calves between January 2011 and June 2021. Cases were most commonly seen between May and July and in calves between one and two months of age (Figs A, B; data for dairy calves included for comparison). There is no evidence of a second peak following autumn calving. Fig AOpen in figure viewerPowerPoint SRUC VS diagnoses of perforated abomasal ulcers in calves up to six months of age, 2011 to 2021 Fig BOpen in figure viewerPowerPoint Age of calves diagnosed with perforated abomasal ulcers, 2011 to 2021 Only 2 per cent of the calves were described as thin, and 80.4 per cent were in good body condition. Males were slightly over-represented accounting for 56.7 per cent of cases. Losses due to perforated abomasal ulcers are usually isolated incidents and the majority of affected calves are found dead (Fig C). The diagnosis is straightforward but the aetiology is not understood. Suggested risk factors are listed below but, even when identified, proving cause and effect is difficult. Fig COpen in figure viewerPowerPoint Ruptured abomasal ulcer in a four-week-old suckler calf Concurrent disease or stress. Mechanical trauma due to abnormal contents such as grit/sand or hair balls. Viral infection such as bovine viral diarrhoea (BVD). Trace element deficiencies including vitamin E, selenium and copper. Bacterial or fungal infection. Hyperacidity. Further review of postmortem examination reports found that seven of the calves had pneumonia (described as mild/incidental in four), and five had evidence of navel ill and/or liver abscesses. Hair balls were detected in six and the presence of sand/silt was noted in the abomasal contents of four. Twenty-four calves were screened for BVD virus with negative results. These findings suggest that these proposed risk factors are of minimal or no importance. Liver trace element analysis was rarely carried out but, of the five calves tested, selenium results were low in all cases. These numbers are too small to draw any conclusions, but further investigation may be warranted. It has been suggested that clostridial species bacteria have a role in the pathogenesis of abomasal ulceration and perforation. Bacteriology and/or fluorescent antibody testing was carried out in around two-thirds of cases and results do not support any link between the two. In addition, histopathology failed to detect any evidence of clostridial abomasitis in the 41 cases examined. A primary bacterial abomasitis was suspected in two cases, implying that infection is also of little importance overall. Sarcina species bacteria were observed histologically in 15 cases, indicating an abnormal abomasal bacterial flora. Sarcina species proliferate when there is an excess of fermentable carbohydrate within the abomasum. This could result if a degree of tympany develops following ingestion of a large volume of milk. Sarcina species ferment sugars, producing carbon dioxide, which can prolong tympany, potentially reducing mucosal perfusion. Other products of fermentation such as acetate, hydrogen and ethanol can cause chemical damage to the mucosa and may reduce the pH, which further slows abomasal emptying. It is hypothesised that a repeated cycle of mucosal damage triggered by large intakes of milk may predispose to abomasal ulceration and perforation. Providing advice on how to reduce the wastage caused by this condition is problematic as the initiating cause remains unclear in many cases. Lung cultures were sterile and histopathology confirmed chronic bacterial pneumonia; however, no evidence of infection with M bovis was detected. As S ruminantium can be isolated from the tonsils of healthy cattle, focusing on the hygiene of stomach tubes and feeding equipment was suggested as a means of trying to prevent further cases. Skin diseases A neonatal shorthorn cross calf was euthanased and submitted to investigate areas of hair loss over the dorsum, distal limbs and head (Fig 3). A similar calf had been born in 2020 but no testing was carried out. Fig 3Open in figure viewerPowerPoint Epidermolysis bullosa in a neonatal calf Epidermolysis bullosa was suspected and confirmed on histopathology. This revealed extensive absence of epidermis often associated with haematoidin and haemosiderin pigments in the dermis indicating previous episodes of haemorrhage linked to separation of overlying epidermis. In sections where epidermis remained there was multifocal separation from the dermis. The epithelia of the tongue and oesophagus were also affected. Further history is being sought regarding the breeding of the calf. A 140-cow suckler herd submitted a stillborn three-quarter salers cross calf to investigate the cause of congenital alopecia. A similar calf had been born to a different cow two years previously. The calf was believed to be full term but weighed only 16 kg with a crown-rump length of 71 cm. Hair was only present around the eyes and on the tail, ears, forehead and distal limbs. The thyroid was enlarged (30 g) and oedematous (Fig 4). Fig 4Open in figure viewerPowerPoint Hyperplastic goitre in a salers calf with congenital hypothyroidism Histopathology confirmed diffuse hyperplastic goitre with no colloid present and the thyroid iodine content was very low at 70 mg/kg dry matter (DM) (reference range >1200 mg/kg DM). Hair follicles were present in usual numbers but were underdeveloped without hair shaft formation. Similar cases have been recorded in salers cattle whereby they fail to synthesise thyroid hormones despite adequate dietary iodine.3 Hypothyroidism can also delay myelination and hypomyelination was an additional finding in this case. Small ruminants Nutritional and metabolic disorders A three-week-old Texel cross lamb was noted to be off colour before being found dead the next day. Postmortem examination revealed free blood in the abdomen originating from a 9 cm tear in the liver. The liver appeared large and pale and histopathology detected diffuse macro- and microvesicular hepatic vacuolation consistent with widespread lipid accumulation. Ovine white liver disease was considered as a differential diagnosis but the lamb was unusually young and ceroid pigment was not detected. Despite this, liver analysis confirmed low cobalt levels; <0.02 mg/kg DM (reference range ≥0.06 mg/kg DM). Other differential diagnoses included toxicity, which was deemed unlikely, a metabolic defect or a congenital enzyme deficiency. Generalised and systemic conditions A flock reported the death of 15 lambs from a group of 60 over a short period and the carcase of a three- to four-week-old Texel lamb was submitted for investigation of the problem. A fibrinous pleurisy, pericarditis and peritonitis were detected on postmortem examination. An organism suspected to be a non-haemolytic strain of Mannheimia haemolytica was isolated and considered to be the cause of death. Concentrate feed had been introduced one week earlier, the rumen pH was 4 and this was considered to have predisposed to the outbreak. A flock of Shetland sheep reported ataxia and neurological signs in neonatal lambs with 30 per cent of the lamb crop dying at one to two days of age. Lambs appeared healthy at birth and colostrum management was good. Postmortem examination of a typical case revealed a pericardial effusion containing a fibrin clot but no other abnormality. Epsilon toxin was detected in small intestinal contents and histopathological examination of kidney and brain confirmed lesions consistent with a diagnosis of neonatal pulpy kidney (clostridial enterotoxaemia type D). This condition is preventable by clostridial vaccination of ewes, which was advised for the future. Nervous system disorders Swaledale encephalopathy was suspected as the cause of neurological signs in two-week-old Swaledale lambs from five separate flocks. Affected lambs were reported to be ataxic with rapid clinical deterioration. There were no significant findings on postmortem examination. Screening for border disease virus and louping ill virus was carried out in one flock and proved negative. Neuropathology revealed a polioencephalopathy/interface encephalopathy typical of Swaledale encephalopathy in all cases.4 In one flock all the affected lambs were known to have been sired by a new tup. Information on breeding history was not available for all flocks; however, this condition is believed to be hereditary. Pigs Generalised systemic diseases The carcases of three eight- to 10-day-old piglets from different litters were submitted to investigate an ongoing problem with a low level of sudden deaths in neonatal piglets from a 560-sow herd. Postmortem examination findings included marked distention of the small and large intestines with liquid yellow contents but no evidence of diarrhoea. A suspect isolate of Clostridium difficile cultured from the small intestines of one piglet was tentatively identified as such by MALDI-TOF (matrix-assisted laser desorption ionization-time of flight mass spectrometry). C difficile antigen was detected by ELISA in the faeces of two piglets. Histopathology identified widespread acute bacterial necrotising colitis in one case. When considered in combination, the findings were highly suggestive of enterotoxaemia associated with C difficile. No other neonatal enteropathogens were identified; however, one piglet was diagnosed with secondary septicaemia due to Mannheimia varigena, an organism occasionally associated with disease in cattle and pigs. C difficile-associated disease is most common in neonatal piglets between one and seven days of age and spores shed in sow faeces are the primary source of infection. Good colostrum management and a clean environment are essential in preventing this condition. All piglets in this herd received an injection of tulathromycin as a prophylactic measure against joint ill. However, such antimicrobial prophylaxis may encourage overgrowth of C difficile by disrupting the natural gut flora. The client was encouraged to submit further cases with an emphasis on culturing C difficile on selective media for potential autogenous vaccine production. Birds A dead buzzard (Buteo buteo) submitted for routine avian influenza screening was found to be thin with a prominent keel and no fat stores. Multiple spherical creamy-white abscesses up to 0.5 cm in diameter were found scattered throughout the liver (Fig 5). Fig 5Open in figure viewerPowerPoint Avian tuberculosis lesions in the liver of a buzzard A Ziehl-Neelsen stained impression smear of liver tissue revealed acid-fast bacilli supporting a diagnosis of avian tuberculosis. Avian tuberculosis affects a wide range of bird species and was also confirmed as the cause of chronic wasting in a backyard khaki Campbell duck. Postmortem examination findings in this case were atypical and included multiple abdominal masses of varying colour, size and shape plus countless, dark, 1 mm oval structures attached to the ovary by a cord of fibrous tissue. Adenocarcinoma of the oviduct was suspected, but histopathology revealed multiple granulomatous lesions with prominent epithelioid macrophages and giant cells consistent with tuberculosis. Miscellaneous species Wild animals A female mountain hare (Lepus timidus) was submitted after being found moribund before death. The carcase was thin and numerous ticks and lice were present. The strongyle egg count was high (10,950 eggs per gram) and considered significant. DISEASE ALERTS The following conditions were reported by SRUC VS disease surveillance centres in August 2020. Given similar climatic and production conditions, they could also be important this year. Parasitic pneumonia in cattle Purchased cattle, unvaccinated calves in their first grazing season and older cattle with a limited previous grazing history are at highest risk of parasitic pneumonia. Any outbreaks where the response to treatment is poor should be investigated further and discussed with the relevant pharmaceutical company. Underdosing can be an issue especially when treating heavier cattle. Spironucleosis in pheasant poults Outbreaks of disease can occur shortly after the transfer of birds from rearing to release pens and are triggered by the stress of handling, transportation and introduction to a new environment. Pens that have been used in previous years are higher risk. Affected birds are dull, diarrhoeic and can lose weight rapidly. There was no evidence of louping ill and histopathological examination of tissues found only mild changes in the liver and kidneys suspected to be secondary to the intestinal parasitism. References 1De Regge N, van den Berg T, Georges L, Cay B. Diagnosis of Schmallenberg virus infection in malformed lambs and calves and first indications for virus clearance in the fetus. Vet Microbiol 2013; 162: 595– 600CrossrefCASPubMedWeb of Science®Google Scholar 2Okura M, Maruyama F, Ota A, et al. Genotypic diversity of Streptococcus suis and the S suis-like bacterium Streptococcus ruminantium in ruminants. Vet Res 2019; 50: 94– 109CrossrefPubMedWeb of Science®Google Scholar 3Watson PJ, Scholes SF. Congenital goitre and alopecia in pedigree Salers cattle. Vet Rec 2010; 166: 29– 30Wiley Online LibraryCASPubMedWeb of Science®Google Scholar 4Scholes SFE, Higgins RJ, Holliman A, et al. Subacute symmetrical necrotising encephalopathy in young lambs. Vet Rec 2007; 160: 775Wiley Online LibraryCASPubMedWeb of Science®Google Scholar CONTACTING SRUC VS SRUC Veterinary Services can be contacted by telephone on 0131 535 3130 or by email: vcedinburgh@sac.co.uk Contact details for local SRUC VS disease surveillance centres are available at www.sruc.ac.uk/contactvetservices Volume189, Issue224/31 July 2021Pages 61-65 FiguresReferencesRelatedInformation