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Aquaculture > Lecture 9 > Flashcards

Lecture 9 Flashcards

1
Q

Where does nephrocalcinosis occur

A
  • Intensively farmed salmon
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2
Q

What is nephrocalcinosis associated with

A
  • High ambient free CO2 levels and/or nutritional aspects involving magnesium deficiency or selenium toxicity
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3
Q

Signs of fish with nephrocalcinosis

A
  • Abdominal swelling
  • Exophalmia
  • Ventral haemorrhage
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4
Q

What is diagnosis of nephrocalcinosis based on

A
  • Gross lesions
  • Histopathological changes showing edposits in the collecting ducts which typically stain dark blue in HandE sections and black with von Kossa stain
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5
Q

What is furunculosis

A
  • Infection with the bacterium Aeromonas salmonicidia subsp. salmonicida
  • Intracellular so can avoid host immune defences
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6
Q

When do outbreaks of furunculosis occur

A
  • Temperatures above 10 degrees
  • In young fish: 2-4 degrees
  • Endogenous stressor and exogenous stressors
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7
Q

How does horizintal transmission occur with furunculosis

A

Via water column

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8
Q

Where have furunculosis been detected

A

Surface of fertilised eggs

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9
Q

How is vertical transmission with furunculosis prevented

A

Iodine

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10
Q

Why are fish that survive furunculosis a problem

A

They are carriers

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11
Q

What is the gross pathology of furunculosis

A
  • Mortalities withouy any clinical signs other than darkening of skin can occur in peracute infections, particularly in juvenile salmon
  • Depends on water temperature, fish age and virulence of the agent
  • During the chronic stages the fish show lethargy, inappetence and darkening of the skin, which is similar to most bacterial septicaemias
  • Ventral haemorrhage is common
  • Liquefactive, haemorrhagic furuncles involving skin and or musc;e, progressing to crater lesions are seen in subacute or chronic pt salmon
  • Furuncles not alwyas present and are not a diagnostic deature
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12
Q

Histopathology if furunculosis

A
  • Dense aggregates of bacteria in organs such as heart, kidney, spleen, muscle and gills almost pathogenic
  • Mural thrombi
  • There is remarkably little tissue reaction around agregates of bacteria in early stages of the disease, but tissue necrosis and liquefaction may become extensive in late chronic stages
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13
Q

Aeromonas salmonicida atypical is a biovar for what

A

Acheron is a new typical strains recently described in Tasmaia causing MAS in Atlantic Salmon

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14
Q

What is enteric redmouth disease caused by

A

Yersinia ruckeri - hagerman strain

Virulent form is endemic in australia

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15
Q

What does enteric redmouth disease produce in salmon

A

Produces septicaemic conditions known as yersiniosis

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16
Q

What does enteric redmouth disease cause

A
  • Hyperaemia of the oral cavity and jaw as a result f congestion of the submucosa, is not alwyas evident
17
Q

Transmission of enteric redmouth disease

A

Horizontally and many species of asymptomatic carriers as wellas birds being reservoirs of infection

18
Q

Common signs of Yersiniosis in salmon

A
  • Development of a marked unilateral or bilateral exophtalmos often with frank patces of harmorrhagic congestion o the iris of the eye, a characteristic that gave rise to the epithet salmoinid blood disease
  • Vaccination is used
  • Subcutaneous haemorrhage in the mouth and throat
19
Q

Waht do fish in Australa with Y.ruckeri cause

A
  • Petechiation on the pyloric caecae
  • Hypertrophy of the spleen
  • Peritonitis
  • GIT must be empty
  • Agressive form
    • Erythema around the meninges may also be seen
  • Bacteria are readily detected free in the blood and in circulating and sequestered macrophages
  • Ascites, exophthalmia, cutaneous petehiae and localisation of haemorrhage
20
Q

What is seen with Yersiniosis at necropsy

A
  • Gneral congestion
  • Intestinal haemorrhage
  • Petechiae on serosa membranes
  • Swollen kidney
  • Splenomegaly
21
Q

What is the proper name for sea lice

A

Lepeophtheirus salmonis

22
Q

What is the most NB ectoparasite in salmon farming

A

sea lice

23
Q

How to treat sea lice

A
  • Bay
  • Tidal done
  • Water catchment
24
Q

No. development stages in sea lice

A

10

25
Q

What in the infective free living stage of sea lice called

A
  • Copepodid - found on ventral surface
    • N when doing counts
    • Adults located in scaleless areas
26
Q

Gross pathology with sea lice

A
  • Damage as lic graze on host tissue
  • Skin ulcerations
  • Petechiae
  • Hyperpigmentation
  • Resultant ulcers break the osmotic barrier and are consequently sites for secondary infection
27
Q

treatment of sea lice

A
  • Organophosphates
  • Evamectin benzoate in feed
  • Hydrogen peroxide
28
Q

What are the Caligus spp

A
  • Non-host specific
  • Smaller and ligether than salmon
  • 8 stage lifecycle
    *
29
Q

What is whirling disease

A
  • Myxobolus cerebralisis the causal agent of a persistent and economical important condition termed ‘whirling disease’
    *
30
Q

CS of whirling disease

A
  • Spiralling
  • Darkening of the caudal region and severe skeletal deformities of the cranial area, jaw and opercula
  • Errosion of cartilage surrounding auditory organ causes it - pressure on the caudal nerve
31
Q

What are multifunctional gills

A

Responsible for a number of critical function in addition to respiration, including osmoregulation, excretion of nitrogenous waste, pH regulation and hormone production

32
Q

Proliferative gill inflammatin

A

Describes recurrent gill disease outbreaks that occur in autumn in salmon farms in Norway

33
Q

Proliferative gill disease

A

Occurs in the same season as norway

Called this due to the proliferative histological features and uncertain aetiology and with probably less infection

34
Q

Complex gill disease

A

Used to refer to this varied syndrome of probable multifactorial aetiology and variable histopathology anf the term encompasses the syndromes referred to as PGI or PGD

Aquaculture (11 decks)

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