Mes: Abril 2019

Cataracts in Salmonids – Gross Pathology

Eye
by Carlos Sandoval
Atlantic salmon with cataract. Note that the opacity occupies more than 75% of the lens.

Cataracts are changes in the clarity of the lens so that it appears cloudy. Such changes are a clinical or gross diagnosis, and there may be no histopathological correlate. Nevertheless, opacity of the lens results in reduced ability to see. Cataracts may be divided into primary or secondary disease. In primary cataract, opacity of the lens is the only sign of disease in the eye, while in secondary cataract the lens changes occur as a consequence of other intraocular disease. A wide variety of causes...

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Strawberry Disease in Rainbow Trout– Histopathology

Skin
by Hugh Ferguson
Figure 1. Strawberry disease in rainbow trout in freshwater showing loss of scales, and accompanying haemorrhage into the scale pockets. Note the severity of the dermal inflammation, which is mostly mononuclear, and largely avoids the epidermis.

Strawberry Disease (SD) is a chronic, nonlethal skin condition that affects Rainbow Trout (Oncorhynchus mykiss) in the United States, several European countries (Scotland, England, Switzerland, Germany, France, among others), Chile and Peru (Sandoval 2017, unpublished report). In Europe it is also known as Red Mark Syndrome (RMS) or Cold-Water Strawberry Disease (CWSD). SD is characterized by raised, sometimes bright red inflammatory lesions that can occur in almost any size of fish bigger than fingerlings, but usually in growing or market-sized fish. The disease presents as...

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Epitheliocystis in Cobia – Histopathology

Gills and Pseudobranchs
by Carlos Sandoval
Cobia, gill: abundant lamellar basophilic inclusions are observed, consistent with severe epitheliocystis infection H&E

Aquaculture of cobia (Rachycentrum canadum) has gained popularity in the last decade, and this species is now farmed in several countries in Latin America and Asia. Epitheliocystis is a chlamydia or rickettsia-like organism infecting the gills and skin of a variety of species in both fresh and saltwater. The disease has been reported in at least 90 species of marine and freshwater fish in both the southern and northern hemispheres. At least four bacterial species may be involved in this condition: Candidatus Piscichlamydia salmonis (Salvelinus...

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Strawberry Disease in Rainbow trout – Gross Pathology

Skin
by Hugh Ferguson
Rainbow trout with SD, showing characteristic bright-red lesions on the skin, and scale loss.

Strawberry Disease (SD) is a chronic, nonlethal skin condition that affects Rainbow Trout (Oncorhynchus mykiss) in the United States, several European countries (Scotland, England, Switzerland, Germany, France, among others), Chile and Peru (Sandoval 2017, unpublished report). In Europe it is also known as Red Mark Syndrome (RMS) or Cold-Water Strawberry Disease. The severity of the skin lesions suggests a hypersensitivity response, but hypersensitivity to what?  Affected fish respond well to immune suppressors including corticosteroids, but also to a wide range of antibiotic treatments, suggesting that...

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