Two mortality events in sea-caged yellowtail kingfish Seriola lalandi Valenciennes, 1833 (Nannopercidae) from Western Australia

In November 2008 a commercial sea-cage operator farming yellowtail kingfish, Seriola lalandi, in Western Australia reported more than 70% mortality of the sea-caged fish. Several parasites and potentially pathogenic bacteria were isolated from the fish, but despite a detailed laboratory investigation the cause of the mortality event was never ascertained. That episode of deaths was followed in January 2009 by a smaller mortality event in fish in a sea cage that had been stocked several weeks earlier. Pathogens similar to those seen in the first mortality event were isolated, but again a single causative agent could not be identified. Multiple stress factors resulting in immunosuppression may have precipitated the mortality events.     

Infection with Photobacterium damselae subspecies damselae and Vibrio harveyi in snapper, Pagrus auratus with bloat

OBJECTIVE: To diagnose the cause of chronic, low mortality associated with bloat in tanks of snapper at an aquaculture facility. DESIGN: A clinical, pathological and microbiological investigation into the cause of a low number of ongoing mortalities associated with bloat in snapper at an aquaculture facility is outlined. Necropsy, histology, microbiology and a comparison of haematology and water analysis from affected and unaffected fish and holding tanks, respectively were conducted. RESULTS: Affected moribund fish were found in lateral or dorsal recumbency floating on the water surface within 24 hours of death. Photobacterium damselae subspecies damselae was isolated from intestinal contents and Vibrio harveyi from the blood of affected fish and both were isolated from culture water. Both V harveyi and P damselae subspecies damselae isolates were sensitive to tetracycline, ciprofloxacin and sulphamethoxazole plus trimethoprim. Environmental parameters such as pH and dissolved oxygen were similar in tanks of affected and unaffected fish. Affected fish had gas distended swimbladders, anaemia, and the intestines were diffusely distended with a clear, pale yellowish fluid. Livers were mottled tan and green in a zonal pattern. Histologically the intestines of fish from tanks suffering mortality had a moderate granulocytic enteritis with oedema and infiltrations with eosinophilic granule cells that were also present as an infiltrate in the gills. There were elevated numbers of melanomacrophage centres and haemosiderin deposits in the spleen, kidney and liver of affected fish. CONCLUSION: Vibrio harveyi and Photobacterium damselae subspecies damselae infection should be recognised as potential pathogens of snapper held in water of less than optimal quality.     

Microsporidia (Encephalitozoon cuniculi) in wild rabbits in Australia

Objective To determine the prevalence of infection with Encephalitozoon cuniculi i n wild rabbit populations in Western Australia, and to isolate the organism from seropositive rabbits.
Design Serological screening of wild and clinically affected domestic rabbit populations.
Sample population Eighty-one wild rabbits from southwestern Western Australia and 29 laboratory rabbits.
Procedure Indirect immunofluorescence antibody technique and in-vitro amplification of parasite isolates in fibroblast cultures.
Results Of the 81 wild rabbits and 29 laboratory rabbits, 20 and 22 respectively, had antibodies to E cuniculi . E cuniculi from the urine of one seropositive laboratory rabbit and from brain and kidney tissues of eight and five seropositive laboratory and wild rabbits respectively were isolated in fibroblast cultures.
Conclusion E cuniculi infection has been shown for the first time to be prevalent in wild rabbits in Australia. Techniques have been developed for the isolation and culture of the causative agent. Comparative studies can now be undertaken to determine risk factors for clinical disease in domestic rabbits and the relationship among E cuniculi isolates from wild and domestic rabbits.     

Caligus sclerotinosus (Copepoda: Caligidae), a serious pest of cultured red seabream Pagrus major (Sparidae) in Korea

Caligid copepods (Crustacea) known as sea lice are pests of cultured fish, causing serious diseases and economic losses in fish aquaculture worldwide. One species, Caligus sclerotinosus Roubal, Armitage & Rohde, 1983 (Caligidae), is considered a serious pest of the highly prized red seabream Pagrus major (Temminck and Schlegel, 1843) (Sparidae) cultured in Japan. Recently, in neighboring Korea, red seabream culture has intensified and almost replaced yellow tail culture. However, until now, there have been no reports on infection of this sea louse from red seabream in Korea. We surveyed 120 (20 fish per month) P. major from a sea ranched Tongyeong Marine Research Center aquaculture facility, Gyeongsangnamdo, Korea for six months in 2011 (June to November). We recorded severe infection by the sea louse C. sclerotinosus on the skin of P. major. Prevalence was 100%, mean intensity 7.06, maximum intensity 49, and minimum intensity 2. Adult females (624), males (219) and few chalimi (5) were observed and identified by their morphology. As an average of all our collections, less than 0.6% of individuals were chalimi. We suggest, therefore, that adults of C. sclerotinosus undergo ontogenetic host switching after their final moult. No infection of C. sclerotinosus was found on wild P. major collected from Tongyeong and Yeosu fish markets on the southern coast of Korea. Severe infection by this sea louse may cause secondary infections of the host. This copepod is already reported from Australia and Japan and hence, this is the first report from Korea. We expect this pest to have an impact on Korean red seabream fisheries equally serious to that being experienced in Japan.     

Artificial reproduction of wild and cultured barbel (Barbus barbus, Cyprinidae) under controlled conditions

The aim of this work was to compare the effects of controlled reproduction of cultured and wild common barbel, Barbus barbus (L.). Preparations containing different GnRH analogues and dopamine receptor antagonists (Ovopel, Ovaprim) as well as human chorionic gonadotropin (hCG) (in the case of cultured fish) were applied and their influence on ovulation, spermiation and quality of gametes obtained was determined. No differences in the qualitative or quantitative parameters of semen were found between fish stimulated with different hormonal preparations and those not receiving hormonal stimulation. The high suitability of Ovaprim for ovulation induction in (cultured and wild) barbel was confirmed. The highest synchronisation of ovulation was obtained after the application of Ovopel (18 ± 3 h), but the best results of controlled reproduction (expressed as the percentage of ovulations and survival of embryos) were obtained by applying Ovaprim (83.2 ± 4.1). A significantly higher percentage of ovulation was obtained in cultured fish (80-90%) than in wild fish (< 25%).     

Polycystic kidney disease in goldfish (Cusrassius auratus)

Abstract Thirty percent of 60 goldfish in an outside pond showed progressive development of swollen abdomens and floatation problems. The occasional fish was found dead. Necropsy of an affected fish showed an abdomen almost filled with a large bilobed ventral mass comprised of masses of cysts filled with clear fluid. On histopathological examination, this mass appeared to be composed of large cystic spaces lined by a single flattened epithelium. Occasional remnants of normal kidney tissue were seen withen the mass.     

Polycystic kidney disease in goldfish (Cusrassius auratus)

Thirty percent of 60 goldfish in an outside pond showed progressive development of swollen abdomens and floatation problems. The occasional fish was found dead.

Necropsy of an affected fish showed an abdomen almost filled with a large bilobed ventral mass comprised of masses of cysts filled with clear fluid. On histopathological examination, this mass appeared to be composed of large cystic spaces lined by a single flattened epithelium. Occasional remnants of normal kidney tissue were seen withen the mass.     

Hereditary hydrocephalus in laboratory-reared golden hamsters (Mesocricetus auratus)

A colony of golden hamsters had an ongoing problem with hydrocephalus. In an attempt to clear the colony of the problem, new breeders from another supplier had been purchased. At termination of a behavioral study, the brain was collected from 35 animals (four of which had died with hydrocephalus during the study) and was examined macroscopically and by light microscopy. Although no animals manifested obvious behavioral changes, 31 of 35 (88.6%, 13/15 males and 18/20 females in control and manipulated groups) had hydrocephalus. Twenty-five animals had macroscopically identifiable hydrocephalus, and six had hydrocephalus identified microscopically. Neither teratogenic concentrations of metals nor mycotoxins were detected in tissues or food, and sera from breeders tested negative for antibodies to Sendai virus, reovirus 3, and lymphocytic choriomeningitis virus. Trial matings of breeders expected to produce hydrocephalic offspring resulted in affected offspring, and mating of breeders expected to produce normal offspring resulted in normal or less-affected offspring. Hydrocephalus was confirmed retrospectively in some breeders. Hereditary hydrocephalus appears to be widespread in hamster stocks in Central Europe. Affected animals do not manifest signs of disease and usually die without obvious premonitory signs. Despite severe hydrocephalus, the animals can breed, and animal handlers do not identify motor deficits or abnormal behavioral activity. This entity is unlike the previously described, hereditary hydrocephalus of hamsters that is phenotypically identifiable and usually is lethal before they attain breeding age.     

Rudimentary Coronary Artery in Syrian Hamsters (Mesocricetus auratus)

Congenital underdevelopment of one or more main branches of the coronary arteries has been reported in man, but not in non-human mammals. In man, this defective coronary artery arrangement may cause myocardial ischaemia and even sudden death . The main goal of this study was to describe the coronary artery distribution patterns associated with the presence of a markedly underdeveloped (rudimentary) coronary artery in Syrian hamsters. Moreover, an attempt was made to explain the morphogenesis of these patterns, according to current knowledge on coronary artery development. Eleven affected hamsters belonging to a laboratory inbred family were examined by means of internal casts of the heart, great arterial trunks and coronary arteries. The aortic valve was tricuspid (normal) in seven hamsters and bicuspid in the other four. A rudimentary coronary artery arose from the right side of the aortic valve in four specimens, from the left side of the aortic valve in a further three, and from the dorsal aortic sinus in the remaining four. In all cases, a second, well-developed coronary artery provided for all the coronary blood flow. Except for the existence of a rudimentary coronary artery, the present anomalous coronary artery distribution patterns are similar to coronary artery patterns reported in Syrian hamsters, dogs and humans in association with a solitary coronary ostium in aorta. We suggest that an unusual prolonged time interval in the development of the embryonic coronary stems might be a key factor in the formation of coronary arteries displaying significantly dissimilar developmental degrees.     

Cutaneous plasmacytoma in three golden hamsters (Mesocrietus auratus)

Spontaneously occurring cutaneous tumours in three golden hamsters were characterized using histological, immunohistochemical and ultrastructural methods. Histologically, the tumours were composed of sheets of round to oval plasmacytoid cells with eccentrically placed nuclei. Tissue sections were weakly positive for anti-B lymphocyte antigen (BLA) staining. Ultrastructurally, large amounts of rough endoplasmic reticulum in the cytoplasm were observed. BLA positivity and characteristics of ultrastructure showed the plasma cell origin.     

Spontaneous uterine leiomyosarcoma in a golden hamster (Mesocrietus auratus)

Uterine leiomyosarcoma occurring spontaneously in a domestic golden hamster was examined histologically and immunohistochemically. The histological findings for this tumour were similar to those for leiomyosarcomas described in other species. Immunohistochemical examination demonstrated the positivity of neoplastic cells with alpha-smooth muscle actin and desmin. From the results mentioned above, the tumour of this case was revealed to be of smooth muscle origin. To our knowledge, this is the first report of a uterine leiomyosarcoma in domestic golden hamsters.     

Cycad (zamia) poisoning in Australia

The Cycads belong to an ancient family of plants and were the cause of the first well documented plant poisoning in Australia when Captain Cook's men and their pigs were affected by eating them. Subsequent reports particularly by early explorers refer to toxicity of the seeds to man. One reason for this was the evidence that the natives ate them. Subsequent reports and experimental work established the toxicity to sheep and cattle. In sheep and cattle 2 syndromes occur, ataxia and liver damage. In cattle the former is the better known, the spinal cord lesion being mainly a demyelination of the sensory pathways. The liver damage is necrosis and fibrosis.