Fish (KP) Flashcards
Skin response to Bacterial injury?
- Aeromonas & Vibrio → dermal localization → ulceration
- Flavobacterium → Yellow pigmented bacteria → ulceration, yellow skin
Which fish tissues are capable of extreme regeneration w/ little to no scarring?
TQ
Cariac
Muscle
Retina
Skin
CNS
How much of the Gills do you have to lose before you see clinical signs?
(TQ)
50%
What are the gills responsible for & can be effected during gill insult?
(TQ)
- Gas Exchange
- Acid/base balance
- Osmoregulation
- Excretion of ammonia & carbon dioxide
How do gills respond to chronic injury?
TQ
Hypertrophy of the epthelial cells & fusion of the lamaelli →
increases gas diffusion distance & turbulence over the gills
Where does inflammation occur in the gills?
Mostly in the central venous sinuses b/c of large # of inflammatory cells
What is a Chaetoceros?
How does it harm the gills?
TQ
- Filamentous diatom with backward pointing spines
- act like burrs & fish can’t remove on it’s own
- Cause physical damage & severe acute bronchitis
What is a common bacterial gill disease?
Where does it cause infection?
What drugs help?
- Flavobacterium branchiophilum
- Superficial infection of the surface of gills
- NSAIDs - b/c prostaglandin-mediated vasoconstriction in gills
What is the anatomy of the fish heart?
TQ
- Single chambered system
- Atrium
- Ventricle
- Bulbus arteriosus
What is the difference between fast swimming & slow swimming fish hearts?
TQ
- Fast swimming →ventricle has a compact outer layer→ coronary blood vessels ⇒ aerobic oxidative metabolism
- Slow swimming →Spongy layer only →no coronary blood vessels →glycolytic metabolism
In a fish what is CO more depenent on?
CO = SV * HR
TQ
Stoke Volume (SV)
What can cause cataracts in fish eyes?
TQ
- Toxins from bacteria
- Eye flukes - Diplostomum flexicaudatum
What are the factors that cause gas bubble disease in fish?
What does it do to the fish?
What can help prevent it?
TQ
-
Causes:
- Rapid increase in water temp or rapid decrease in pressure
- Drop in pressure experienced by blood passing across gills
- Gas bubbles cause emboli in the vessels of the gills, chorioid gland (eye), pseudobranch & elsewhere
- Prevented by aerating the water
What is most of the kidney made up of?
TQ
Hemopoietic tissue
(main hemopoietic organ)
What is different about the fish kidney as compared to mammals?
TQ
- Kidney in fish = liver in mammals
- Fish kidney has no cortex or medulla (so no LOH) → can’t concentrate urine like mammals
- Renal portal MØs → act to phagocytoses foreign substances
Which can fish tolerate better?
A rise or drop in water temp?
TQ
- Drop in water temp
Warm water holds less O2 than cold.
How can this be harmful to the fish?
TQ
- Increases in water temp → increase in metabolism → increased metabolic/developmental rate → increase in O2 demand
- Increased susceptibility to bacterial infections
- Once fish can no longer extract enough O2 ⇒ respiratory distress syndrome
What can happen to your eggs/fry kept in water that is too warm?
TQ
- Spinal abnormalities
- cardiac abnormalities
- increase suceptibility to bacterial diseases
NH3 + H2O ⇔ NH4+ + OH-
pH & Temperature determine which way this equation goes
What will increase the amount of free ammonia (NH3)?
What will increase the amount of ionized ammonia (NH4+)?
TQ
- Increases in pH shift the equation to the left = more free ammonia = danger
- Increases in Temp. shift the eqation to the left = more free ammonia = danger
But wait…gills secrete ammonia, how come it doesn’t hurt the fish?
Gills also secrete CO2
- CO2 +H2O → H2CO3 (carbonic acid) → Lowers pH = protective mechanism
Is an increased amount of ammonia secreted by the gills damaging to the fish?
Nope
Is an increase in ammonia in the body damaging to the fish?
Yep = interference with neurtransmitters = coma
What is the nitrification cycle?
How is it accomplished?
- Ammonium → Nitrite → Nitrate
- Bacteria in the environment
- Nitrosomonas converts Ammonium → Nitrite
- Nitrobactor converts Nitrite →Nitrate
What is the impact of too much CO2?
TQ
- Impacts the carbonic anhydrase system → metabolic acidosis → impacts gas excretion into swim bladder (distention) and eye (exophthalmos)
- STOP FEEDING THE GOLDFISH!!!
What is hemorrhagic septicemia and in what fish would you find it?
- Acute gram neg bacterial dz associated with high water temps
- Bacteria have long filamentous structure
- Fresh water fish
What will you see in a fish
with hemorrhagic septicemia?
- Hemorrhagic necrosis of hematopoetic tissue, kidney, spleen & intestinal mucosa
- Congestion at base of fins & around vent
- Intussesception
- Swollen soft kidney & spleen
What 3 things are responsible for hemorrhagic septicemia?
- Aeromonas hydrophilia → Zoonotic, FWF
-
Aeromonas samonicida
- Furunculosis in salmonids & goldfish
- Pasteurellosis→ “Yellow tail” in Japan
What bacteria is responsible for atypical bacterial dz in fish?
Why is it atypical?
Pseudomonas
Atypical because
- hemorrhagic septicemia more common in marine environment and low temps
- does not have long filamentous structures
- Causes lethargy, sleepiness & stumpy gills
Yellow pigmented bacterial Dz or myxobacterial dz is caused by what types of gram negative bacteria?
- Flavobacterium columnare (columnaris Dz)→ fresh water
- Tenacibaculum → saltwater (jellyfish mouths)
- Flavobacterium branchiophilum → Bacterial gill Dz
- Flavobacterium psychrophilum → BacT Cold water Dz
What is the most important yellow pigmented bacterial Dz of fish?
Columnaris Dz (Flavobacterium columnare)
- Necrotizing dermatitis @ > 18*C
- Saddle patch lesion around dorsal fin
- Cotton-wool mouth
- Gills
What is peduncle Dz?
- bacteral cold water Dz caused by flavobacterium psychropilum
- Tail rot
- loss of scales & severe dermis erosions on peduncle
- necrotic myositis
What gram positive bacteria casue bacterial kidney dz in fish?
- Renibacterium salmoniarum → kidney & liver→spawning rash
- Streptococcus iniae → Caribbean → ZOONOTIC
- Vibrio
-
Tuberculosis→acid fast Mycobacterium marinum→ ZOONOTIC
- Skin lesions = miliary granulomas (TQ)
- Francisella (not tularenis)
- Edwardsiella → Enteric Septicemia
What causes Tuberculosis in fish
what does it look like?
How can it be diagnosed how?
What do you have to be careful off?
TQ
- Mycobaterium marinum
- Very common in freshwater fish
- scales stand up & fish cannot get rid of water →ranal insuffeciency
- Impression smears & acid fast staining
- ZOONOTIC → skin lesions → Miliary granulomas
What causes white spot dz in vietnamese catfish and what are the lesions?
- Edwardiella ictaluri (enteric septicemia)
- Multifocal granulomas
What viruses does the OIE recoginse as important?
- Infectious hematopoietic necrosis (IHN)
- Viral hemorrhagic septicemia (VHS)
- Spring Viremia of Carp (SVP)
What 7 viral Dz of fish are notifiable according to the OIE?
(Know the US ones)
- Infectious Hemoatopoietic Necrosis (IHN) - Pacific Northwest
- Spring Viremia of Carp (SVC) - Great Lakes
- Infectious Salmon Anemia (ISA)
- Viral Hemorrhagic Septicemia (VHS)- USA great lakes
- Epizootic Hematopoietic Necrosis (EHN) - Down Unda
- Oncorhynchus masou virus (Herpes salmonis serotype2) - Oncogenic
- Koi herpesvirus (CH3)
What does Infectious Pancreatic Necrosis (IPN) do to fish?
- Catarrhal enteritis
- Exocrine pancreatic necrosis
- Hepatic necrosis esp. in young fish
What are the Rhabdoviruses important in fish?
- Infectious hematopoietic necrosis - N. America, Europe
- Severe necrosis of melanomacrophage in renal interstitial hematopoietic tissue
- Viral Hemorrhagic Speticemia - European version of IHN
- hemorrhage
- Spring Viremia of Carp
WHat are the Cyprinid Herpeis viruses? (3)
- Cyprind herpes 1 → Carp Pox (not a pox virus since its listed under herpes duh)
- Cyprind herpes 2 → Goldfish herpes virus
- Cyprind herpes 3 → Koi herpes virus
What do the Cyprinid herpesviruses do to fishes?
- Targest skin & gills
- Causes inclusion bodies
- HIGH MORTALITY
- Secondary Columnaris disease - koi- dz of gills
What is Lymphocystis and what are the two types?
Iridovirus Infection
- Superficial → dermal infection targeting fibroblasts = become massively enlarged
- Mainly skin - especially fins
- causes cytomegaly of skin cells
- doesn’t kill fish
- Systemic
- Causes cytomegalic cells
What dz causes chronic fatigue syndrome in fishes?
- Alphavirus
- Salmon - Pancreas Dz
- Trout - Sleeping Dz
- rhabdomyopathy: lesions starting in heart & skeletal (striated & red mm)
- Especially severe in trout - cant maintain position in water
- muscle will repair & regenerate itself
What virus causes Infectious Salmon Anemia & what does it do to fish?
- Orthomyxovirus
- Necrosis of liver
- Most blood pools in liver - “lacking blood”
- pale gills
What are the 3 viral Dz where there are heart lesions?
-
HSMI - Heart & Skeletal Muscle Inflammation
- Peritoneal cavity w/ blood tinged fluid, patchy pallor in liver, skeletal mm lesions, NO pancreatic involvment
-
Cardiomyopathy Syndrome
- Rupture of atrium or complete CVS failure - lesions in spongy myocardium
- Totiviridae in big fat healthy fish NO pancreatic involvment
- Pancrease Dz
What virus causes Viral Encephalopathy & retinoopathy (VER)?
- Nodavirus aka vacuolating encephalopathy aka spongiform encephalopathy
- vacuolar degeration of brain & retina
- comon in farmed fish
- pigmentation with clinical signs of abnormal swimming
What causes walleye dermal fibrosarcoma?
Retrovirus associated dermal fibrosis
What species would you see retrovirus associated lymphoma?
Pike and muskiesrus
What is the only example of a metastatic fish tumor?
Aflatoxin induced hepatic carcinoma
What type of fish are most suseptible to alflatoxin induced hepatic carcinomas and what fugal infection does it result from?
- Salmonids & hybridized fish
- Aspergillus flavus
What is not a tumor but could be confused as one?
Goiters - thyroid is not encapsulated (most spp) so with hyperplasia you will find follicles all over the place
What is “ich” ichthyophthirius multifiliis?
- A parasite of fish that causes white spots that appear superficial but are below the epidermis
- coffee-ground-like cytoplasm with horseshoe shaped micronucleus
- can be costly and dangerous in koi- flagellated
What do colonial parasistes indicate?
They are commensals and indicate low water quality
What parasite can cause protein losing enteropathy in fish?
- Heamita, spironucleus
- 4 pair flagella
- can go systemic
- can get 2º bacT infections
What are myxozoa what do they cause and how are they classified?
- White muscle lesions
- Extracellular parasites
- classified by spores
- Hitozoic = within tissue = more damaging
- Coelozoic = with in caviites
What is a notifiable parasitic dz or fish?
Whirling Dz of trout - Myxobolus cerebralis
What is the IH of myxobolus cerebralis and what are the lesions?
- IH = oligochaete worm Tubifex
- Targets cartilage of head adn spine
- mostly yound=g fish
What causes Proliferative Kidney Dz?
The pre-spore stage of a myxosporean
What are the lesions of proliferative kidney disease and when does it occur?
IH?
- Kidney swells & fish die of myelopthisis like anemia
- parasites are in the hematopoietic tissue of kidney & spleen
- Occurs at 15*C and above
- IH bryozoa
What tiny intracellular parasite is acid fast?
Microsporidia
What are the two classes of flukes that infect fish and what do they cause?
- Class Monogenea
- Move around vigorousley
- Class Digenea
- Larval digeneans - black spot dz- host melanin response
- Diplostomum spathaceum -eye fluke- larval stage
What is a zoonotic roundworm (nematode) that fish get?
- Codworm
- causes gastric granulomas - cooking/freezing kills it
What type of parasite is the most devastating of freshwater fish?
How do you TX?
- Crustation parasistes - O. copepoda (Anchor worm)
- mature female is usually seen attached to fish
- Infeed Ivermectin, organophospates or pick off w/ tweezers
Which type of fish have thicker epidermis?
TQ
Scaleless fish
Where do the lateral line sensory canales join with those on the head?
Supra and infra optic areas
How do gills effeciently extract O2 from the water?
Via counter current exchange between water flow over gills and blood flow
What part of the gills does most of the blood go through?
TQ
Central venous sinus
What do diffuse change in the gills indicate?
Most likely a toxic issue and indicates poor water quality
What typically causes infarction in the gills?
TQ
Fungl infections or bacterial infarctions
Can clubbing of the gills be seen with the naked eye?
What can cause it?
TQ
- Yes → multifocal lesions
- Cochiopodium (an amoeba)
What is the major type of fish farming?
TQ
Cage culture
What are fish important?
TQ
- pets
- monitors of environmental health
- lab animals
Fish dont have eyelids so how do they control light coming into eye?
TQ
- By using melanin from RPE is pumped up and around the photoreceptors
- takes 30min-1hr
- Daytime - photoreceptors contracted into RPA
- Nightime - melanin contricted back into RPE
What are the clinical signs of Orange chomide iridovirus?
- congestion around head
- purple color enlarged cells in microscope
What causes Strawberry Dz?
What lesions do you see?
- 2°ary Crycropalum infection
- Full thickness, non-neutrophilic dermatitis
What 2 bacteria have vaccines available to protect fish?
- V. anguillarum
- V. somonicida
