Results
All cases were diagnosed as AMC based on their state of congenital
generalized arthrogryposis (Figure 1). Generally, the cervical spine had
torticollis, while the thoracic spine showed either scoliosis or
kyphoscoliosis associated with aberrant course of the ribs. This had let
to narrowing of the thoracic cavity and consequently pulmonary
hypoplasia and abnormal shape of the heart. The skeletal muscles had
undergone lipomatous atrophy, especially affecting muscles of the limbs,
pelvis and axis. The joints of the limbs had various combinations of
flexure and extension and both bilateral symmetric and asymmetric
arthrogryposis was found (Figure 1). All cases had reduced body weight
but normal amount of fat depots thus reflecting the severe muscular
atrophy. Mild to severe hydrocephalus was observed in four cases. The
mesencephalic duct was malformed in two (Figure 2) and the cerebellum
grossly hypoplastic in one case. Additional malformations were present
in some calves (Supplementary table S1). None of the calves had received
colostrum.
Real-time RT-PCR and ELISA analyses revealed that one case was positive
for SBV viral RNA (case 1), one case was positive for both viral RNA and
fetal anti-SBV antibodies (case 2) and five cases were positive only for
fetal anti-SBV antibodies. The pleural effusion fluid of one calf scored
in the doubtful measuring range of the antibody ELISA (case 7). All dams
were seropositive for SBV (Table 1). Indication of other concomitant
viral infections were not found.
The cases originated from 7 herds located in South-West of the Jutlandic
peninsula (Figure 3) and within a distance of less than 150 km. Five
cases clustered within a radius of only around 20 km (Figure 3). Two
cases originated from Holstein dairy herds while five cases were beef
cattle breeds. An insemination date was recorded for four cows and
ranged from July 17th to August 7th2020, while the other three females were mated naturally during summer
grazing. Additional case data are shown in Supplementary table S1.