5/6/2024: 

Since the start of the BTV serotype 3 outbreak in the Netherlands, the NWVA (Food and Consumer Products Safety Authority) has received 1,575 reports of clinical suspicions of infection with BTV-3 and 4,421 positive PCR test results (reference date 08-Jan-2024). The clinical appearence observed in individual animals is variable and the severity of the symptoms also varies from farm to farm. In addition to laesions in the mouth and on the tip of the nose and the udder, fever, conjunctivitis, red mucous membranes and lame animals with swollen coronary bands of the claws, regurgitation and loss of the claw capsule have also been reported. The symptoms reported also include drops in milk production and increased mortality. Pathological examinations of cattle suspected of having BTV-3 showed mostly erosions and ulcerations of the mucocutaneous transitions at the edge of the lips and the tip of the nose, ulcerations and petechiae in the oral cavity and pharynx, petechiae on the heart, the pulmonary artery and the aorta. Acute muscle degeneration was seen in various animals in the oesophagus, ruminal pillars and/or cardiac muscle. The muscular degeneration seen in the oesophagus in several animals may possibly explain the clinical observations of problems swallowing and regurgitation. The pathological findings also gave the first clear evidence of vertical transmission of BTV-3, with the virus being detected in the spleen of three premature or full-term aborted calves.

On instructions from LNV (the Ministry of Agriculture, Nature and Food Quality), GD launched a project for further investigation of the clinical appearence of BTV-3 and its impact on cattle and sheep farms, which included five cattle farms. The aim is to determine the prevalence within a herd and to find out if there are subclinically infected animals. Additionally, an initial descriptive analysis of the effect of the BTV-3 outbreak on milk production and cattle mortality was carried out at the end of the third quarter of 2023 for the Animal Health Monitor for Cattle. During the bluetongue outbreak in 2023, milk production per cow per day fell at all groups of farms for which livestock health had been affected to a greater or lesser degree by BTV-3. The largest drop in milk production was seen on farms that reported clinical symptoms to the NVWA. From the time of reporting and for nine weeks thereafter, milk production at these farms fell by an average of almost one kilogram per cow with respect to the same period in previous years (2020-2022). In terms of the location and time, cattle mortality seemed to correspond to the presence of a BTV-3 infection, with the greatest increases in mortality being among adult cattle (older than 2 years) at dairy farms. Mortality levels remained higher for a long time both at farms in an infected area that had not reported BTV-3 cases (up to 1.5x higher than in 2020-2022) and at farms that reported clinical symptoms (up to nearly 3.5x more deaths than in 2020-2022). Analyses will be carried out in the first half of 2024 looking at this in greater depth to give further interpretations of the findings. Read the full article

More information from the Highlights report cattle

• Deformed calves from the same breeding bull at two dairy farms
• Update on the insensitivity of bacteria in material from animals from non-dairy farms
• Increase in the number of diagnoses of excessive keratinisation cornification of the rumen
• Increase in the number of diagnoses of respiratory inflammations or pneumonia
• Increase in the number of diagnoses of lungworm
• Animal health of cattle in the Netherlands, fourth quarter of 2023

 

Read the Highlights report cattle (April 2024)