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CVSOH 4 > Fish Medicine > Flashcards

Fish Medicine Flashcards

1
Q

What are the stocking densities used for fish?

A
  • 2.5cm of fish for every 72cm2 of water surface area
  • 2kg of fish per 1000 litres
  • area available for oxygen exchange
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2
Q

What is energy used for in fish?

A

Not expended to maintain body temperature - used to maintain osmoregulation, pumping water out of the body that has entered by osmosis

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3
Q

What does it mean that fish are poikilothermic?

A

Their body temperature is dependent on that of the surrounding environment.

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4
Q

What does water temperature effect?

A

Metabolic rates and hence growth and immune response

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5
Q

What is the effect of a change in water temperature?

A

Rapid changes in temperature (over a couple of degrees) are potentially harmful to the fish

For many cold water fish their immune response is impaired below 12oC

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6
Q

What is water hardness?

A

Water hardness is a measure of the divalent metal ions present in the water, mainly Magnesium and calcium. Water Hardness will stabilise the pH acting as a buffer

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7
Q

What ratio will be a well buffered pond?

A

A hardness over 100mg/l CaCO2

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8
Q

What are the forms of nitrogen in ponds and tanks?

A
  • In its ionised form, ammonium NH4+, it is relatively non toxic, but in the form of ammonia it is highly toxic
  • Bacteria such as nitrosomonas in the water and on the surface of the filters metabolise ammonia oxidising it to nitrite, this too is toxic to fish
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9
Q

What is the effect of high nitrite on fish?

A

Skin irritation
Lethargy
Difficulty breathing

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10
Q

How is water treated to prevent or remove excess nitrite?

A

Partial water changes, adding salt to the water will reduce the toxic effects of nitrite

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11
Q

How are fish anaesthetised?

A
  • Anaesthetic agent in aqueous solution.
  • The fish is placed into the solution and this acts as an inhalational anaesthetic passing into the blood stream through the gills and in turn into the CNS
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12
Q

How are fish recovered from anaesthetic?

A

Recovery is brought about by placing the fish back into fresh water where then anaesthetic is excreted back into the water via the gills and to a lesser extent the kidneys

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13
Q

What is the anaesthetic agent used in fish?

A

Phenoxethanol

Or MS222 (Tricaine methane) a highly soluble white crystalline powder

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14
Q

How long can be fish be kept out of the water for clinical examination and procedures?

A

Up to 5 minutes

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15
Q

Describe stage 1 of anaesthesia.

A

Light sedation - slight loss of reactivity

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16
Q

Describe stage 2 of anaesthesia.

A

Deep sedation - total loss of reactivity except to strong pressure, equilibrium normal

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17
Q

Describe stage 3 of anaesthesia.

A

Partial loss of equilibrium - erratic swimming, increased gill movements

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18
Q

Describe stage 4 of anaesthesia.

A

Total loss of equilibrium - reactivity only to deep pressure stimuli

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19
Q

Describe stage 5 of anaesthesia.

A

Loss of reflex activity - total loss of reactivity, very shallow opercular movements

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20
Q

Describe stage 6 of anaesthesia.

A

Medullary - gasping followed by gill movements

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21
Q

What is assessed when observing the fish in its own environment in clinical examination?

A

-Where are the fish in the water? Are they near the filter trying to get oxygen?
- Are they swimming normally?
- Are they collecting round fountain, water aerators etc? (a sign of hypoxia)
- Are they rubbing against objects or the surface of the water? Parasites?
- Are there any gross lesions visible? Ulcers are the most common

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22
Q

What is assessed upon clinical examination of the eyes?

A

The size and shape of the globes
Corneal damage

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23
Q

What are the species variations in mouths?

A

Some (marine) species of fish have hard beak like teeth which may over grow and stop the fish eating, as this is worn down by biting coral in the wild

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24
Q

How should the gills appear in clinical examination?

A

Should be liver pink, but shouldn’t be pale or grey

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25
What is assessed upon clinical examination of the skin?
Oedema Haemorrhage Abrasion or ulceration noted Mucus samples should be taken Pink blush to fins or other parts of the skin is a sign of septicaemia in fish
26
What is assessed upon clinical examination of the fins?
Parasites and damage to the fin membrane
27
What is assessed upon clinical examination of the anus?
For patency
28
What is assessed upon clinical examination of the abdomen?
Palpated for any abnormal swelling; masses or fluid may be identified
29
What are the diagnostic tests available for fish?
- Mucus scraping - Gill and fin preparations - Bacteriology - Blood sampling - Radiography - Ultrasonography - Post mortem
30
How is blood sampling done in fish?
1. A ventral approach inserting the needle into the ventral midline caudal to the anal fin 2. The needle is advanced until it hits the vertebral column then withdrawn slightly 3. Alternatively a lateral approach entering just below the lateral line may be used
31
What are the routes of medication administration for fish?
- In water meds - antiparasitics, fungal drugs - In food meds - Gavage – place medications down the back of the throat but either large crop tube or syringe - Injection - Topical – to form a seal over ulcers to prevent fluid loss and to enable healing
32
What is the problem with in water medications?
It is not really appropriate for antibiotic administration as it will damage any bacterial filter systems. Many antibiotics are also inactivated by hard water
33
What is the problem with in food medications?
Antibiotics in the fish world there is often resistance to the antibiotics that can be provided in this form
34
How are fish injected?
1. Caught and sedated to administer 2. Injections are generally given intramuscularly, the preferred site being in the midline just in front of the dorsal fin 3. An alternative site is into the flank lateral to the dorsal fin
35
Why is caution taken with antibiotic use in fish?
- Some drugs are chelated by hard water - Care adding to water as will destroy the bacteria in filters - Over use in the fish trade has led to resistance - Ideally base antibiotic use on culture and sensitivity
36
What is the problem with trimethoprim-sulpha antibiotics?
Resistance not uncommon
37
What is the use of ceftazadime/fortum in fish?
Good against gram negatives
38
What is the use of chloramine T in fish?
Use for protozoa and flukes
39
What is the use of formalin in fish?
Ectoparasites, some fish very sensitive. Do not use with salt
40
What is the use of malachite green in fish?
Protozoal infections and antifungal toxic to some fish
41
What is the use of metronidazole in fish?
Poor solubility in water, used for flagellates such as hexamita
42
What is the use of salt in fish?
Antiparasitic, anti-stress and antibacterial Buffers fish to reduce osmotic pressure on fish, antibacterial, cannot combine with formalin in water. Until water is changed, this will not change salinity
43
What is the use of benzalkonium chloride in fish?
Bacterial infections and gill disease
44
What is the use of zeolite in fish?
Removal of ammonia from water
45
How are fish euthanised?
Anaesthesia (MS222 or phenoxyethanol) followed by pentobarbitone injection or severing spinal cord behind gill cover
46
What are the first aid protocols for fish?
1. Test water quality 2. Quarantine affected fish 3. Change 30% water 4. Add salt at the rate of 2g/l to reduce physiological stress. (Care if owner used formalin) 5. Stop feeding temporarily. (this will reduce waste excretion) 6. Improve aeration 7. Do not add medications indiscriminately
47
What are the species affected and the clinical signs of koi herpesvirus disease/cyprinid herpes III?
Common carp - Lethargy or erratic behaviour - Loss of balance - Sunken eyes - Necrotic patches in the gills
48
What are the species affected and the clinical signs of spring viraemia of carp/rhabodivirus carpio?
Carp and other coarse fish species - Darkening of the skin - Protruding eyes - Abdominal swelling - Pale gills - Trailing faecal casts - Protrusion of the anus
49
What are the species affected and the clinical signs of infectious haematopoietic necrosis?
Salmon and trout - Lethargy with period of frenzy - Darkening of skin - Pale gills - Distended abdomen - Protruding eyes
50
What are the species affected and the clinical signs of viral haemorrhagic septicaemia?
Rainbow trout - Haemorrhaging - Protruding eyes - Anaemia - Spiral swimming behaviour
51
What are the species affected and the clinical signs of epizootic haematopoietic necrosis?
Rainbow trout and perch - Abdominal distension - Darkening of the body - Reddening fin bases - Skin ulcers
52
What are the species affected and the clinical signs of infectious salmon anaemia?
Farmed salmon. - Pale gills - Distended abdomen - Lethargy - Lack of appetite - Protruding eyes - Gasping at water surface
53
What are the species affected and the clinical signs of bacterial kidney disease/renibacterium salmoninarum?
Salmonid species - Lethargy - Skin darkening - Protruding eyes - Blood-filled blisters on the flanks
54
What are the species affected and the clinical signs of epizootic ulcerative syndrome/aphanomyces invadans?
Farmed and wild fish in fresh and brackish waters - Red spots - Blackish burn-like marks - Deep ulcers at the base of fins and over the body
55
What are the species affected and the clinical signs of gyrodactylus salaris/fluke?
Atlantic salmon Fish have a white or grey appearance often with secondary fungal infections
56
What are the clinical signs of mycobacterium species/fish TB?
- Local no healing ulcers - Reduced appetite, weight loss, body deformities - Zoonosis
57
How is mycobacterium species/fish TB managed?
Quarantine new fish for 2 months Cull affected individuals
58
List the common problems seen in fish.
Ulcer disease Furunculosis – aeromonas salmonicida Aeromonas species and pseudomonas External parasites – flashing, slime disease Dropsy Respiratory disease Swimbladder problems Carp pox Lymphocysis – iridovirus Fungal – fish fungus/saprolegnia
59
List the external parasites in fish.
Trichodina species White spot – ichthyophthirius multifillis Flukes Fish lice – argulus species Sea lice – Lepeoptheirus salmonis, Caligus elongatus
60
What is dropsy?
Dropsy is a symptom not a disease, it is used to describe any coelomic swelling
61
What is a possible cause of large ulcers on the side of the face and sides?
Poor water quality, bacterial infection, parasites, trauma
62
If a swab was taken from the ulcer which organism would be most likely to be found?
Aeromonas hydrophila
63
What are the characteristics of aeromonas species and pseudomonas?
- Motile aeromonads and pseudomonads are ubiquitous in soil and water - Rarely primary cause problem but very common secondary invaders and will often mask primary cause - A. Hydrophila most commonly found - Often demonstrate antibiotic resistance
64
What are the acute and chronic clinical signs of aeromonas salmonicida/furunculosis?
Acute – sudden death Chronic – darker colour, lethargic and anorexic and reddening at base of fins
65
How is aeromonas salmonicida/furunculosis treated?
Antibiotics
66
How would you treat ulcers?
Debride and clean with iodine, pack with waterproof gel and inject antibiotics. (Suture will not work as skin is not elastic, will never close this)
67
What is ulcer disease secondary to?
Septicaemia or trauma
68
How is ulcer disease treated?
- GA, debride - Clean with iodine and pack - Inject antibiotics - Correct underlying problem – parasites, water quality
69
What are the characteristics of trichodina species?
- Protozoal parasite - Affect all species - Fresh and marine water - Direct lifecycle - Skin and fin damage
70
How are trichodina species treated?
Formalin, malachite green
71
What are 3 flukes affecting fish?
Dactylogyrus/gill flukes – freshwater Gyrodactylus/skin flukes – fresh and marine Metazoal parasites
72
How are flukes treated?
Praziquantel Chloroamine T
73
How are fish lice/argulus species treated?
- Difficult to kill, will rip fish to shreds - Emamectin – lice solve - 2% salt water baths kill juveniles but okay for adults - Placing branches into pond as a site for egg laying then removing and drying out
74
What are sea lice?
Lepepptheirus salmonis and caligus elongatus Naturally occurring crustaceans that live on fishes skin and cause a lot of damage Affects – L. salmonis – salmonids, Caligus elongates – most marine fish
75
How are sea lice treated?
Husbandry, medications, biological control (Ballen wrasse), looking at vaccines and other interventions
76
What is reddening fins a sign of?
Septicaemia
77
What is the most likely cause of ascites?
Dropsy and pine coning caused by septicaemia and kidney failure by failure to regulate fluid in the body.
78
How is dropsy treated?
Salt water bath, antibiotics may not be unreasonable if signs of septicaemia, reality that euthanasia is the best option if fluid in the abdomen
79
Name 3 causes of dropsy.
Liver/kidney failure Septicaemia Tumours
80
What is a sign of swimbaldder problems?
It is floating upside down at the top of the tank and doesn’t seem able to right itself
81
What initial treatment might you suggest to try and help swimbladder problems?
Warm up the water by a couple of degrees. Pneumonocystic duct connects swim bladder to the gut. Increased water warmth with increase solubility of oxygen in the water.
82
What are the causes of swim bladder diseases?
Temperature fluctuations Bacterial infection Space occupying lesions
83
How are swim bladder diseases treated?
Starve for 48 hours, salt, increase water temperature crushed peas
84
What are the differential diagnoses for raised white patches on the body?
Lymphocytsisic, white spot/ichthycophirius multifillis, mycobacterial, fungus, koi herpes virus
85
How is white spot/ichthyophthirius multifillis treated?
Formalin, chloramine T
86
What are the characteristics of lymphocystitis?
- Iridovirus - Benign disease causing nodular swelling on body and fins - Virus infected dermal fibroblasts (individual cells) causing them to hypertrophy up to 100,000 times - No treatment - Some fish may recover spontaneously
87
How is a fish with saprolegnia treated?
Cull the fish, potentially contagious. Could treat formalin and malachite for other fish and tank Minimise stress, formalin, bronopol – neither that effective, cull severely affected fish
88
What is saprolegnia?
Chronic superficial fungal infection Affects all fish and there eggs, primarily in freshwater
89
What are the clinical signs of saprolegnia?
Cotton wool like tufts on skin and gills, secondary to other problems

CVSOH 4 (35 decks)

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