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Pathological manifestations in rainbow trout (Oncorhynchus mykiss) following experimental waterborne infection with Yersinia ruckeri serotype O1 biotype 2 (strain 07111224) were investigated. Rainbow trout were exposed to 8 × 10 7  CFU/ml of Y. ruckeri by bath for 6 hr, and mortality was then monitored for 22 days post-infection (dpi). Organs were sampled at 3 dpi and also from moribund fish showing signs of severe systemic infection such as bleeding, exophthalmia or erratic swimming behaviour. Y. ruckeri was observed in the meninges and diencephalon of the brain, and lamina propria of olfactory organ at 3 dpi. At 12 dpi, Y. ruckeri had spread throughout the brain including cranial connective tissues and ventricles and the infection was associated with haemorrhages and an infiltration with leucocytes. Y. ruckeri infection and associated with leucocyte infiltration were observed at 13 dpi. In conclusion, Y. ruckeri strain 07111224 causes encephalitis in the acute phase of infection, which could explain why Y. ruckeri-affected fish show exophthalmia and erratic swimming known as signs of ERM., (© 2017 John Wiley & Sons Ltd.)

Severe clinical mycobacteriosis with consistent ocular lesion localization was diagnosed in a population of 800 juvenile tank-reared Cobia (Rachycentron canadum) which experienced a sudden increase in mortality approximately 5 months after arriving into Trinidad and Tobago from Florida, USA. Moderate daily mortality (15-20 animals per day) persisted for just over 1 month. Moribund fish displayed circling behaviour and had an open-mouth gape upon death. Fish consistently presented with bilateral exophthalmia, corneal cloudiness and hyphema. Non-branching acid-fast rods were detected in aqueous humour touch preparations. Histological analysis revealed severe bilateral intra-ocular granulomatous responses in all specimens. Mycobacterium sp. was identified using a real-time PCR assay detecting the RNA polymerase β-subunit (rpoB) gene in different tissue samples. Specimens did not present with characteristic granulomatous responses usually seen in viscera. To the best of our knowledge, this represents only the third documentation of piscine mycobacterial infection presenting with only localized ocular lesions, and the second documented case of mycobacteriosis in cobia. It is, however, the first documentation of an ocular presentation of mycobacteriosis in a marine species and is the first documentation of such a presentation in cobia., (© 2017 John Wiley & Sons Ltd.)

Capture-based aquaculture (CBA) of Atlantic cod (Gadus morhua) has become increasingly important in recent years, and increased attention is being paid to animal welfare issues linked to these activities. Earlier studies showed that some cod develop secondary exophthalmia in captivity. This study investigated the development of secondary exophthalmia in two groups of wild-caught cod, one of which was exposed to rapid decompression causing acute barotrauma (treatment group) while the other was not (control group). Photographs and radiographs before and up to 33 days after barotrauma revealed a significant increase in overall eye protrusion caused by an accumulation of gas in the orbita in the treatment group, first observed on day 9 after decompression, while no protrusions were observed in the control group. Barotrauma was thus identified as an important trigger for the development of secondary uni- or bilateral exophthalmia of wild-caught cod. Two underlying mechanisms are suggested, where the more likely is residual swim bladder gas taking the route of least resistance, while the less likely is the exsolution of gas from the blood. Our results have implications for a wide range of contexts in which cod are rapidly brought to the surface from great depth., (© 2016 John Wiley & Sons Ltd.)

A five-year-old, castrated, male chinchilla rabbit was presented for evaluation of recurrent bilateral exophthalmos. Besides a transient and stress-related exophthalmos with protrusion of both third eyelids, the ophthalmological examination was unremarkable. Plain radiography of the thorax revealed a large precardial mass of soft tissue density. Cytological preparations from the thoracic mass were dominated by small, mature lymphocytes with approximately 10 to 20 per cent lymphoblasts. Computed tomography of the head showed a symmetrical laterodorsal deviation of both eyes without evidence of retrobulbar masses. On necropsy a large cystic mass was present in the cranial thorax associated with severe hydrothorax, hydropericardium and ascites. Histology identified the precardial mass as thymic carcinoma with metastases in the kidneys. This case illustrates the difficulty of diagnosing thymic tumours based on cytological or histological features of the primary tumour alone. To the authors' knowledge, this is the first case of recurrent bilateral exophthalmos associated with a metastatic thymic carcinoma in a pet rabbit.