Nematodirus reminder
Cases of nematodirosis on Scottish holdings are recorded in May every year with a peak of diagnoses in June.
SRUC Veterinary Services recently diagnosed nematodirosis as the cause of death in a six-week-old lamb. This was somewhat unexpected as spring has been quite cold so far. It does highlight however how this disease can be farm, and indeed field, specific.
The weather seems to be warming up and the risk of outbreaks will increase over the next few weeks.
Under laboratory conditions the eggs require a cumulative period of seven days with an air temperature between 11.5 and 17˚C to commence hatching. A further eight to ten days of suitable temperatures are needed to complete the hatch. The emerged L3 larvae are sensitive to UV light and 80% can die over the following month.
The weather forecast for the next seven days predicts that temperatures will be within the hatching range for most of the week – even if the sun isn’t shining.
The SCOPS online Nematodirus forecast is currently indicating a range of risk levels across south-west Scotland/north-west England with some of these increasing following the warm weekend:
- Low risk (Dundrennan): Temperatures within the hatching range but hatch not imminent.
- Moderate risk (Eskdalemuir, West Freugh, Keswick, Shap, St. Bees Head, Walney): Hatching is predicted to start in the next seven to fourteen days if good weather continues
- High risk (Glasgow, Campbeltown, Islay, Carlisle): Hatching predicted to have started.
- Very high risk (Prestwick): Peak hatch.
Aspect and altitude will influence the timing with a later hatch in higher, north facing fields.
Cases of nematodirosis on Scottish holdings are recorded in May every year with a peak of diagnoses in June. Lambs aged six to twelve weeks old are most often affected with concurrent coccidiosis leading to more severe disease. Fields grazed by this age-group year-on-year are highest risk – particularly if an outbreak occurred in 2022.
Posted by SRUC Veterinary Services on 09/05/2023
