Some acute infections are leading to mortality, but more commonly, mastitis leading to lactation failure, lost quarters and early culling.

With most national survey data being historical, Livestock Health Scotland (LHS) worked with 18 volunteer flocks in 2018 to map the incidence of ewe mastitis, identify the causes of infection and test their sensitivity to treatment.

The project investigation was centred on the Moredun Research Institute, with Keith Ballingall and Riccardo Tassi responsible for laboratory work and reporting.

The profiles of the 18 ewe groups were reported at the beginning of the project. Thirty-three mastitis milk samples were submitted by the partner flocks to the laboratory at Moredun for identification, and sensitivity-testing post-lambing.

The majority of flocks were upland, although two BF hill units contributed data. There was therefore a spread of breeds and crosses recorded, with Lleyns, Mules and North Country Cheviots being well represented, as were the crosses of these breeds with Texel, Suffolk and Beltex sires as well as Highlander and Aberfield.

All flocks lambed between 1 March and 25 April, although some producers operated groups of early lambers.

Scan reports ranged from 150% to 213% for the upland/lowground group and 98% and 99% for the hill sheep.

The limited amount of data captured makes analysis of system variables probably less than helpful. However, the majority of flocks lambed inside, with three operating extensive easy-care approaches and three using lambing fields. Ten flocks fed post-lambing with six moving to grass only post-lambing.

Those that reported the mastitis profile post-lambing ranged from an incidence of 0.3% to 2.4%, with the main hill flock reporting 0.15%. Some respondents noted that 2018 had been a low-risk season. The majority of affected sheep were reported to have udder symptoms and to be stiff. A minority were dull or recumbent.

Cases of mastitis in gimmers made up a large proportion of samples submitted to the laboratory.

Mastitis levels peaked in late April and at four to five weeks post-lambing.

Treatment approaches relied on antibiotic therapy. A minority also used intra-mammary tubes or anti-inflammatory therapy. Pen and strep was used by several producers, although oxytetracylines and draxxin were reported as the drug of choice by some flockmasters. On farm, all approaches appeared to deliver a positive response, with very high recovery rates.

Staphylococcus aureus was isolated as the cause of mastitis in 19 samples and was also present in two mixed infections. Two other strains of staph were identified in three samples. Mannhaemia haemolytica was the causal organism in five of the group mastitis cases.

The good news for the sheep sector was that all samples except one were sensitive to the range of antibiotics that were sensitivity-tested. One sample showed resistance to oxytetracylines. There were, however, four samples which showed intermediate resistance to oxytetracyclines and one sample which was identified as intermediate-resistant to kanamycin. Perhaps the high levels of antibiotic sensitivity are reflected in the positive rate of recovery post-treatment.

LHS is indebted to the Moredun scientists and all those on farm who took part, delivered quality samples and made the snapshot survey possible.