Puffy skin disease (PSD) in rainbow trout, Oncorhynchus mykiss (Walbaum): a case definition.
Puffy skin disease (PSD) is a disease that causes skin pathology in rainbow trout, Oncorhynchus mykiss (Walbaum). Incidence of PSD in UK fish farms and fisheries has increased sharply in the last decade, with growing concern from both industry sectors. This paper provides the first comprehensive case definition of PSD, combining clinical and pathological observations of diseased rainbow trout from both fish farms and fisheries. The defining features of PSD, as summarized in the case definition, were focal lateral flank skin lesions that appeared as cutaneous swelling with pigment loss and petechiae. These were associated with lethargy, poor body condition, inappetance and low level mortality. Epidermal hyperplasia and spongiosis, oedema of the dermis stratum spongiosum and a mild diffuse inflammatory cellularity were typical in histopathology of skin. A specific pathogen or aetiology was not identified. Prevalence and severity of skin lesions was greatest during late summer and autumn, with the highest prevalence being 95%. Atypical lesions seen in winter and spring were suggestive of clinical resolution. PSD holds important implications for both trout aquaculture and still water trout fisheries. This case definition will aid future diagnosis, help avoid confusion with other skin conditions and promote prompt and consistent reporting.
Institute of Aquaculture, Stirling University, Stirling, UK.
C E
CE
Maddocks
Environment Agency, Brampton, UK.
E T
ET
Nolan
Centre for Environment, Fisheries and Aquaculture Science (Cefas), Weymouth laboratory, Weymouth, UK.
S W
SW
Feist
Institute of Aquaculture, Stirling University, Stirling, UK.
M
M
Crumlish
Institute of Aquaculture, Stirling University, Stirling, UK.
R H
RH
Richards
Environment Agency, Brampton, UK.
C F
CF
Williams
D000818:Animals; D005393:Fish Diseases / Q000453:epidemiology* / Q000473:pathology*; D046529:Microscopy, Electron, Transmission; D017686:Oncorhynchus mykiss / Q000502:physiology*; D015995:Prevalence; D012867:Skin / Q000473:pathology / Q000648:ultrastructure; D012871:Skin Diseases / Q000453:epidemiology / Q000473:pathology / Q000662:veterinary*; D006113:United Kingdom
aquaculture; case definition; disease; pathology; skin; trout