Anemia in salmon aquaculture: Scotland as a case study.

Anemia in salmonid aquaculture is a recognized blood disorder resulting from the reduction of hemoglobin concentration and/or erythrocyte count. Because of sub-optimal oxygen supply to the tissues, as a negative impact of anemia fish will experience reduced growth and poor health. This health challenge may be linked with several factors including anthropogenic changes in the marine environment, infectious etiology (viral, bacterial, and parasitic), nutritional deficiencies, or hemorrhaging. From the mid-late summer of 2017 to 2019, Scottish salmon farming companies began to report the occurrence of anemic events in open-net marine sites. At that time, the industry had little understanding of the pathogenesis and possible mechanisms of anemia and limited the ability to formulate effective mitigation strategies. Clinical examination of fish raised suspicion of anemia and this was confirmed by generating a packed cell volume value by centrifugation of a microhematocrit tube of whole anticoagulated blood. Company health team members, including vets and biologists, reported discoloration of gills and local hemorrhages. This paper reviews various commercially significant cases and lesser-known cases of anemia in cultured salmonid species induced by various biological factors. The current methods available to assess hematology are addressed and some future methods that could be adopted in modern day fish farming are identified. An account of the most recent anemic event in Scottish farmed Atlantic salmon (Salmo salar) is presented and discussed as a case study from information provided by two major Scottish salmon producers. The percent of total marine sites (n = 80) included in this case study, that reported with suspected or clinical anemia covering the period mid-late summer 2017 to 2019, was between 1 and 13%. The findings from this case study suggest that anemia experienced in most cases was regenerative and most likely linked to blood loss from the gills.

Technical pre-analytical effects on the clinical biochemistry of Atlantic salmon (Salmo salar L.).

Clinical biochemistry has long been utilized in human and veterinary medicine as a vital diagnostic tool, but despite occasional studies showing its usefulness in monitoring health status in Atlantic salmon (Salmo salar L.), it has not yet been widely utilized within the aquaculture industry. This is due, in part, to a lack of an agreed protocol for collection and processing of blood prior to analysis. Moreover, while the analytical phase of clinical biochemistry is well controlled, there is a growing understanding that technical pre-analytical variables can influence analyte concentrations or activities. In addition, post-analytical interpretation of treatment effects is variable in the literature, thus making the true effect of sample treatment hard to evaluate. Therefore, a number of pre-analytical treatments have been investigated to examine their effect on analyte concentrations and activities. In addition, reference ranges for salmon plasma biochemical analytes have been established to inform veterinary practitioners and the aquaculture industry of the importance of clinical biochemistry in health and disease monitoring. Furthermore, a standardized protocol for blood collection has been proposed.

A pilot study of acute phase proteins as indicators of bovine mastitis caused by different pathogens.

This study analysed three acute phase proteins in milk from natural cases of bovine mastitis and compared their profiles across different pathogens causing the infection. Their ability to differentiate subclinical and clinical mastitis from normal (uninfected) milk samples was also examined. Samples from various dairy farms across Scotland submitted to the Veterinary Diagnostic Services unit of the University of Glasgow were used for this study. They were subjected to microbiological examination for mastitis pathogens, evaluation of somatic cell counts and analyses by ELISAs for haptoglobin, C-reactive protein and mammary associated serum amyloid A3. Each acute phase protein (APP) was compared across pathogens and form of mastitis. Significant differences (P = 0.000) were observed for each APP between causative pathogen and form of mastitis. There were significant correlations between the pathogen and the form of mastitis and the 3 APP showed similar profile for the different pathogen type and forms of mastitis. It can be concluded that the aetiological pathogen of mastitis to a large extent influences the clinical form of the disease, this, ultimately being reflected in the degree and course of secretions of the acute phase proteins; Hp, M-SAA3 and CRP into milk during mastitis. Variations of which, show correspondent patterns with related pathogen/form-of-mastitis.

Evaluation of the modified Glasgow Prognostic Score to predict outcome in dogs with newly diagnosed lymphoma.

The modified Glasgow Prognostic Score (mGPS) assigns a numerical value (0-2) from pre-treatment serum concentrations of C-reactive protein (CRP) and albumin to predict patient outcome. CRP and albumin were evaluated in 77 untreated dogs with lymphoma to determine the relationship of mGPS to clinicopathological parameters and whether it could predict progression-free (PFS) and overall survival (OS) in treated dogs. mGPS distribution was significantly associated with clinical stage, substage b, weight loss, gastrointestinal disturbances and lethargy at presentation. On univariate analysis, mGPS was significantly associated with OS and PFS, with shorter median survival times for mGPS 2 compared to mGPS 0 and 1 combined. Hypoalbuminaemia significantly reduced OS and PFS, however increased CRP had no effect. Only clinical stage was significantly associated with OS and PFS on both univariate and multivariate analysis. mGPS has potential prognostic value for canine lymphoma , but further studies are needed.

Assessment of the incidence of GDV following splenectomy in dogs.

OBJECTIVE: To establish if splenectomy increases the incidence of gastric dilatation and volvulus (GDV) in dogs. METHODS: Two case-series studies of cases and controls were performed. Records of dogs that had undergone splenectomy (37 cases) were compared with records of dogs that had undergone other abdominal surgery (43 cases). Records of dogs that presented for non-elective gastropexy (33 cases) were compared with records of dogs presented to the hospital for unrelated reasons (39 cases). Survival following splenectomy and development of GDV in the first 12 months following surgery were retrieved from the clinical records and by questionnaire-based canvassing of the referring clinician. The incidence of GDV following splenectomy was established and the association between a current episode of GDV and previous splenectomy was assessed. RESULTS: There was no evidence that splenectomy was associated with an increased incidence of subsequent GDV (P=0.469). No association between a current episode of GDV and previous splenectomy was found. CLINICAL SIGNIFICANCE: Splenectomy is not associated with an increase in the incidence of GDV.

Renal dysplasia and nephrosclerosis in calves.

Renal dysplasia and nephrosclerosis in six calves, which were aged three to six months and from different farms in western Scotland and north-west England, was characterised clinically by stunted growth and renal failure with uraemia. Affected animals were depressed and one case exhibited severe neurological signs. Reduced erythrocyte counts were evident in three of four animals from which blood samples were submitted for haematology. At postmortem examination, the kidneys were bilaterally small, pale and firm, with marked fibrosis and sometimes contraction of the capsule. Histologically, affected calves had disorganised atrophic glomeruli, dilatation of tubules, loss of nephrons, areas of undifferentiated mesenchyme and diffuse interstitial and periglomerular fibrosis. There was minimal inflammation. Renal dysplasia and nephrosclerosis is a form of juvenile nephropathy of unknown aetiology that occurs sporadically in calves in the UK.