Histopathology of vitamin C deficiency in a cichlid, Cichlasoma urophthalmus (Günther)

Abstract. This paper describes the histopathological changes observed in the Mexican native cichlid Cichlasoma urophthalmus (Günther) when try with an initial weight of between 160 and 170 mg were fed with diets deficient in vitamin C for 90 days. The epidermis showed an extensive inflammatory response, with spongiosis and also degenerative changes in the basal cells. Muscle showed a range of pathological changes including inflammation, changes in the number and position of the nuclei, vacuolation and necrosis, granular degeneration, and fibre loss. Gills showed thickening of the primary lamellae, oedema, hyperplasia, telangiectasis and atrophy of the bony supporting structures. Ganglia and neurones of nervous tissue were abnormal with changes which ranged from slight inflammation to central chromatolysis. The hepalopanereas was also affected and focal necrosis of the hepatocytes was frequently observed. The pancreas showed major changes with shrinkage of the acinar cells and reduction of zymogen granule content. Fish fed diets containing 0 and 40 mg vitamin C kg^-1 of diet were infected with Mycobacterium sp. and miliary tuberculosis was found affecting kidney, spleen, choroid gland, stomach, heart and muscle. The association between fish tuberculosis and vitamin C deficiency is discussed.     

Frequency and distribution patterns of Saprolegnia infection in wild and hatchery-reared brown trout Salmo trutta L. and char Salvelinus alpinus (L.)

Abstract. Fungal infection of sexually mature brown trout and char was associated with a particular type of Saprolegnia exhibiting a low degree of homothallic sexuality. Hatchery-reared brown trout were more severely infected (in terms of the % area of the body covered with the fungus) than were wild fish. The fins of hatchery-reared fish were particularly prone to Saprolegnia infection regardless of sex. In wild brown trout, a sexual difference in the pattern of infection was demonstrated. The flanks of the male fish appeared to be more prone to infection when compared with the female and there was a greater susceptibility of the caudal and ventral fin of the female when compared with the male. Evidence is presented which suggests that the incidence of infection in mature male salmonid fish prior to spawning is significantly greater than in the females. This difference may not be apparent in spent fish after spawning. These findings are discussed in relation to the background concentration of fungal spores in the water, the behavioural characteristics of spawning fish and differences in epidermal structure.     

The histopathology of acute and chronic infections of rainbow trout Salmo gairdneri Richardson with eye flukes, Diplostomum spp.

Abstract. A histopathological study was carried out on rainbow trout suffering from acute and chronic diplostomiasis. Clinical signs were few in acutely infected fish but in chronic cases fish were blind, exophthalmic and emaciated. Acute infections resulted in subcapsular cataract formation with varying capsular change. Chronically infected fish frequently showed lens dislocation, capsular rupture or duplication and the formation of Elschnig's pearls and Wedl cells. Phacogenic uveitis was seen in many fish with capsular rupture and retinal detachment frequently occurred as a sequal to vitreous detachment.     

Evidence that superficial branchial colonies on the gills of Salmo salar L. are not Aeromonas salmonicida

Abstract. The indirect immunoperoxidase technique (IPT) was used to examine specific superficial colonies of organisms observed on the gills of salmonids. The evidence obtained suggested that the superficial colonies were not a form of Aeromonas salmonicida , the causative agent of furunculosis. Application of the IPT to bacterial smears and previously stained histological sections from a case of furunculosis, confirmed the sensitivity of the technique and suggested the presence of common antigens between A. salmonicida and members of the Vibrionaceae, Pseudomonaceae and Enterobacteriaceae.     

Further consideration of the haematology of proliferative kidney disease (PKD) in rainbow trout, Salmo gairdneri Richardson

Abstract. A study of selected haematological parameters in rainbow trout, Salmo gairdneri Richardson, exposed to proliferative kidney disease (PKD) under field conditions is described. Changes in the blood picture are related to kidney pathology at different stages of the disease. As extensive renal vascular pathology, haemoglobin crystallization and inflammatory lesions developed, there were progressive decreases in haemoglobin and packed cell volume values, erythrocyte numbers declined to less than 50% of those in control fish, and numbers of misshapen erythrocytes increased. Leucopenia, neutrophilia and thrombocytopenia developed, especially in oedematous fish. With recovery, most values were similar to those of control fish. In recovered, re-challenged fish, erythrocyte counts, packed cell volume and haemoglobin values decreased in infected fish compared with uninfected fish. The results of the study are compared with those of other authors and the type of anaemia in PKD is discussed.     

Distribution of lesions in ovine salmonellosis

SUMMARY Four forms of salmonellosis were recognised in feedlots and during transport by sea: septicaemic, and acute, subacute and chronic enteric. The severity and distribution of lesions in the enteric forms varied according to the progression of the pathological process. The acute disease involved the abomasum and small intestine whereas the subacute disease centred on the lower small intestine and upper large intestine. Chronic disease involved considerable mucosal repair in the ileum, caecum and proximal colon. Septicaemic salmoneiiosis was often accompanied by acute enteritis and occasionally by cholecystitis. S typhimurium was the most frequently encountered serotype.