Highlights
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- Plochteach is a photosensitisation disease of lambs grazing on extensive wet pastures in North-West Europe.
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- Affected animals develop liver damage and then skin lesions.
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- The full aetiology is unknown but the plant bog asphodel (Narthecium ossifragum) is implicated.
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- We propose potential ways, including selective breeding, to reduce disease incidence.
Abstract
Photosensitisation
diseases can cause production and animal welfare losses world-wide. In
North-West Europe a photosensitisation disease complex known as
‘plochteach’, ‘yellowses’, ‘saut’ and ‘alveld’ occurs in lambs on
extensive pastures containing bog asphodel (Narthecium ossifragum).
Affected lambs develop lesions on the ears, face and sometimes the
back, with erythema, oedema, ulceration and necrosis that can be
followed by secondary infection and death. Adult sheep appear
unaffected, the incidence in lambs varies from year to year and there
are variations in susceptibility between- and within-breeds. The
definitive cause remains uncertain although ingestion of N. ossifragum,
which contains hepatotoxic saponins, has been implicated in the
aetiology. However, problems replicating the disease complex by feeding N. ossifragum
in a controlled environment have led to alternative hypotheses,
including possible intake of toxins from fungal spores and
cyanobacteria. Further research is required to assess the putative role
of N. ossifragum, the scale of economic and animal welfare
losses associated with the disease, how best to identify affected
animals before external clinical signs appear and the treatment and
management of clinical cases. Given the challenges involved in isolating
the causative agent(s) of plochteach, an animal breeding route may be
effective if heritability of resistance/susceptibility can be
demonstrated.
Keywords
- Lambs;
- Extensive pastures;
- Liver damage;
- Plochteach;
- Alveld;
- Secondary photosensitisation
Copyright © 2015 Elsevier Ltd. All rights reserved.
