Comparative Medicine 2

General features of fish skin

Scales under epithelium → creates osmotic barrier that is easily disrupted

Skin condition is a good indicator of general health of the fish

What is a cuticle

Mucus layer with antimicrobial properties

How do skin lesions of the fish occur

common and easily reognized, thus frequent complaint

Lesions from disruption of osmotic barrier

Water moves into fish causing osmo-regulatory distubrances and tissue necrosis

Features of fish gills

Gill is delicate with one or two cells separating water from blood

Allows efficient O2 exchange

Any epithelial damage can cause significant disease with few visible signs

What does a fish kideny look like

Often paired in higher teleosts, but in salmonids, single (fused)

Always retroperitoneal

Is a filtering organ, great to sample for bacterial cultures

What is the swim bladder of a fish

Present in most fish, lies ventral to the kidney

Involved in buoyancy

Abnormalities produce fish that cannot swim/float properly in the water column

Features of the fish liver

Not a true filtering organ, is generally poor choice for bacterial culture

→ kidney does more of the “filtering” function than the liver in mammals

What are the features of a fish spleen

Is a major filtration and secondary lymphoid organ

Features of fish spleen that show bacteremia

Enlarged, covered in fibrin

Fish and their lymphatic system

No lymph nodes, no lymphatics

What are the features of a fish heart and its components

Low pressure, single circulatory system

Three chambered heart with phagocytic endothelial cells

Is commonly involved in infectious diseases than mammals

Components: sinus venosus, atrium, ventricle (3 chambers), bulbus arteriosus

What are the features of fih eyes

Eye abnormalities common (like exopthalmos)

Choroid rete behind the eye traps bacteria, air bubbles

What is the lateral line in fish

Canal embedded in modified scales, lined by a sensory epithelium called neuromasts

Cells are important in funcctioning to sense pressure changes

What commonly kills fish more than any diseases combined

Overfeeding, overstocking, lackof impropper maintenance and management problems and water quality

What are required water test kits for fish aquariums (salt and fresh water)

Fresh water → ammonia, or nitrite

Salt water → ammonia, nitrite, pH, salinity

Nitrogen cycle in the water in fish aquariums

Ammonia (NH3) oxidized to nitrite (NO2), then oxidized to nitrate (No3)

Nitrate accumulation requires water changes

Oxidation is performed by gram-negative bacteria in the biofilter

What causes methemoglobin in blood/chocolate blood disease

Hemoglobin oxidized to methemoglobin, impairing ability to carry oxygen, leads to dark brown blood and reduce oxygen delivery to tissue

From suboptimal nitrogen cycle management → leads to debility, death, immunosuppression

Filtration can be simple and still work → commercial aids not necessary

Features of the temperature control of the water

Each species has preferred range

Extremes are where toxicity/morbidity occurs

Temperature stress can be induced by continual variation

Oxygen requirements of the fish

Movement at water/air interface allows gas exchange, and aeration provides gaseous exchange

Bacteria that oxidizes ammonia etc. requires oxygen

What are some signs of hypoxia in fish

Piping (going to the top for air)

Arrowhead profile (gills expanded)

What does the filtration system in aquarium do

Oxidation of ammonia into nitrates

Nitrates then removed by water changes

How is salinity of an aquarium measured

Expressed as parts per thousand, or specific graity

Use of chlorine in water

Common treatment for city water supplies

Pre-treating water with sodium thiosulfate (or similar) removes chlorine

Chlorine compounds are acutely toxic to fish, causes branchial necrosis

Use of light in housing fish

Measured in lux

Not often considered to affect fish health

Can be a significant cause of retinal damage → causes blindness

What are 3 bacterial disases important for aquarium fish

Aeromonas hydrophila

Mycobacteria

Columnaris → flavobacterium columnare

Protazoan and Metazoan diseases (1 of each) important for aquarium fish

Ichthyophthirius multifillis/cryptocaryon → protazoan

monogenes → metazoan

Fungal disease important for aquarium fish

Saprolegnia

What are features of aeromonas hydrophila in fish

gram negative, commonly found in fresh water

Causes hemorrhagic septicemia in freshwater fish, associated with water temperature rising

Particularly a problem in koi/goldfish in spring, when water temperature rises

Zoonotic concern

What sort of clinical signs does aeromonas hydrophila cause in fish

Ulcerative

Reddening at the base of fins and scale pockets → typical of fish with bacterial septicemia of any kind

Appear dark, may have acute signs of ascites, lethargy, increased resp

Internal petechial hemorrhage swelling of kidney/spleen also common

How is aeromonas hydrophila treated in fish

abx, like oxytetracycline or florfenicol

Antibiotic resistance is an increasing concern

Features of mycobacteriosis in fish/aquariums

M. marinum, fortuitum, chelonae

Any chronic ulcerative or proliferative lesion that does not heal despite treatment is likely mycobacteriosis

Should assume all tanks are infected

Causes granulomas, usually numerous acid-fast rods with lesions

Zoonosis → “fish finger”

What is columnaris disease in fish

Causative agent = flavobacterium columnare, gram-negative bacterium

Common disease above 15C

What sort of clinical signs does columnaris disease cause

Sometimes seen to stak on top of one another to produce columns when viewing wet mount

“Cotton wool” appearance, or ulcerative/necrotic lesions most typical

Oral lesions can be slight, but cause death

If there are large numbers of organisms, they can be visible intertwined among collagen fibres of dermis

How is columnaris disease diagnosed and treated

Wet mounts of skin/gill most effective way to make fast diagnosis

Timely antibiotic treatment / bath treatment → required to save the fish and prevent spread to tankmates

What causes ich/white spot in fish

Ichthyophthirius multifiliis → cryptocaryon irritans is marine equivalent

What clinical signs does ich/white spot cause

Rupture of epithelium is primary cause of morbidity/mortality → break in osmotic integrity of the tissue

Can be damaging if large numbers of parasites emerge at the same time

Gills/skin most common sites, but eyes/nares/mouth all suseptible

Fish showing signs of irritation and flick themselves off sides of tanks, ponds

How is Ich treated

Life cycle is direct and temperature dependent

topical treatment not effective against mature parasite under epithelium

Immature stage in aquarium is responsive to treatment with topical agents → multiple rounds of bath treatment required

Increase water temp to 30C for 3 days can kill free-swimming ich

Combination of frequent water changes, fish transfers and increased temperature

Is the exception to “treat the fish, not the tank” rule

What does ich look like

So large that it can be seen grossly

Thernt has horseshoe shaped macronucleus, immature tomite is nondescript

Tomite stage encysted in tank environment → susceptible to treatment

Cryptocaryon disease in fish

Same principles as ich

Most protazoa limited to either fresh or salt water → not both

Features of monogenes in fish

Monogenietic trematodes in large numbers causes skin damage, death

They have fearsome haptor to hang on with mouth parts at opposite end to graze epithelium

What is black spot disease in fish

Digenean trematode larvae

harmless to fish, seen in pond fish or those in the wild

Black pigment = melanin

What are features of saprolengia in fish

Several types of fungi can produce lesions as primary pathogens

Can be invasive, therefore difficult to treat

Bath treatment using formalin, salt, hydrogen peroxide, etc.

What is lymphocytstis

most commonly recognized virus in fish, from iridovirus

Causes white proliferative growth on fins → are from massive cytomegaly of fibroblasts

Self limiting infection in most cases → is only clinically relevant when biologic functions are physically compromised

Cataracts as a form of nutritional deficiency in fish

Zinc and riboflavin deficiency is causing this

Cloudy eyes also due to corneal opacity

Spinal issues from nutritional deficiency in fish

Flatfish can get kyphosis and scoliosis due to nutritional deficiency

What causes bloat/dropsy in fish

Various causes

Has abdominal swelling, raised scales like a pinecone, lethargy, increased respiration

Fish struggle with buoyancy due to fluid accumulation

Polycystic kidney disease (PDK) in goldfish

Genetic disorder

Abdominal swelling occurs due to cysts in kidneys causing fluid retention, with poor growth and weight loss

Renal failure, ascites can occur

Neoplasias in fish

Sporadic, but familial/strain disposition can be common

Infectious causes in aquarium species not documented

Respect if possible

What is the general understanding of fish mortality

Mortality of marine fish atrocious

From caught, held, transported to wholesaler, held, mixed, rebagged, treated, etc.

Survival rate is poor

10 golden rules for disease prevention in aquaria

Minimize stress

Water quality → monitor, maintain

Cleanliness/disinfection

Stocking density (don’t overstock)

Feeding practices (don’t overfeed)

Minimizing fluctuations → particularly environmental

Quarantine all new fish

Prophylactic prescription regime → fresh/saltwater, formalin, abx, treatment tank

Record keeping

Disease resistant fish/population → based on species, strain, population mix

what are some examples of instruments that can be used to maintain water quality

Ozonizer

Ozonizer and protein skimmer

Algal scrubbers, Co2 injectors, ultraiolet systems, fluidized bed filters, etc.

6 golden rules in treating fish

Treat the fish, not the tank

Exception where agent is in the tank → ich/cryptocaryon, amyloodinium, monogenes

Doses quoted are always approximate

Species variation

Recommend commercial medications for which active ingredient is on the label

Do not harm

What are some examples of topicas/baths for aquariua species

Dylox and similar chemicals → hydrogen peroxide

Copper sulphate

Formaldehyde/formalin

Potassium permanganate

NO antibiotics

What are some recommended procedures for topical treatment for aquariua

Volume of water accurately calculated

Monitor fish throughout treatment period, be prepared to remove fish

Aerate water

Try a test fish

Why is systemic therapeutants designed for water in fish not very effective

Freshwater fish don’t drink, do not take up eough water across gills to be effective in most cases

Saltwater fish drink, but not enough for drug delivery

Many drugs precipitate in hard/salt water, require higher doses if used in a bath

Oral/parenteral routes preferred

What is integrated pest management

Broad based, and involved a multi-pronged approach

Limiting risk of resistance development

Need to preserve the tools we have by using them effectively, resonsibly

What are some food fish antibiotic treatment options

Florfenicol

Oxytetracycline

Sulfadimethoxine and Ormetoprim

Considerations for oral systemic antibiotic treatment

Incorporated in feed

Top dress, or mixedat manufacture

Palatability

GIT absorption variable

Excretion poorly understood

Exact dosage difficult

But BEST CHOICE

What are some things that need to be done to make a medicated feed for fish

Chosen drug treatment product

Volume of water, total amount to be fed, total biomass of fish, etc

Slurry is made, pellets will expand and take up drug → flake food doesn’t work as well, but can be used

Can be stored

Set amount of feed fed daily → there is generally a daily feed rate range that can be effectively fed ensuring minimum therapeutic dose

Considerations for parenteral systemic antibiotic treatment

IP or IM

Useful for single, or few fish

Many sick fish dont eat

Potential for tissue damage

Generally is impractical/expensive on a large scale, but done in some situations

Features of vaccination for fish

None available for aquarium fish, potential for future (columnaris, mycobacteriosis)

Not a replacement for sound animal husbandry practices

Autogenous vaccine increasingly used in Canadian aquaculture

What are the most important taxonomies for small mammals

Scandentia → treeshrews

Rodentia → rodents

Lagomorpha → rabbites, hares, pikas

Dermoptera → flying lemur

Primates

What are some common rabbit breeds

Holland lop

Lionhead

Mini lop

Mini rex

Dutch

Flemish Giant

Netherland Dwarf

English Angora

Californian

What are some taxonomical features of the guinea pig

Cavia porcellus, a nw hystriocmorph roden

Not found in the wild,

Descended from a related native SA species

What are some breed variations found in guinea pigs

Colours → white, black, brown, red, brindle, mono/bi/tri colour

Hair coat varieties → short haired, long hair, long straight haired, medium length

Satin varieties → hollow hair shaft, recessive genes

Hairless → skinny pig OR baldwin

The varieties can interbreed

What are some common guinea pig breeds

American

Abyssinian

Peruvian

Silkie

Skinny pig

Baldwin

Taxonomy features of chinchillas

hystricomorph rodents

Family chinchillidae

2 species → short tailed chinchilla, long tailed chinchilla

Taxonomy features of the degu

Octodon degus

common degu

Hystrocomorph rodent

Taxonomy features of the rat

Rattus norvegicus domestica

Rattus norvegicus

Myomorph rodent

No distinct breeds, but they have variations

What are the variations that can be found in rats

Colour → coat, eyes

Coat → normal, rex, velveteen, satin/silky, harley

Marking → pattern, ratio of coloured hair vs. white

Body type → manx rat, dumbo rat

Taxonomy features of mice

Mus musculus domestica

Domesticated form - mus musculus

Myomorph rodent

No distinct breeds → variations in colour, coat, marking

Taxonomy features of the gerbil

Meriones unguiculatus

Myomorph rodent

Variations in colour and marking

Taxonomical features of the hamster

Myomorph rodent

Characteristics with large cheek pouches, thick bodies, short tails, excess loose skin

variation: colour, markings

What are common hamster species kept as pets

3 species of dwarf hamster → campbell’s drawf hamster, winter white dwarf, roborobski dwarf hamster

chinese hamster

Taxonomical features of the ferret

Mustela furo

Small, carnivorous

Domesticated form = mustela putorius

Variation in colour, pattern, markings

Taxonomical features of sugar gliders

Petaurus breviceps

Small omnivorous, arboreal, nocturnal

Family petauridae

Variations in colour, markings

Taxonomy features of hedgehogs

Atelerix albiventris

African pygmy hedgehog

Hybrid of white bellied and algerian hedgehog

What are some considerations regarding the anatomy and physiology of the small mammal in a clinical sense

Predator/prey?

Diet → herbivore, omnivore, carnivore

activity → diurnal, nocturnal, crepuscular

Ecosystem → forest, desert, grassland, tundra

Habitat → arboreal, terrestrial, fossorial

Which small mammal has the lowest metabolism

Sugar gliders

Features of rabbits skin

Delicate! Fine hair

Tactile vibrissae

Dewlap in tact in females → fur under the chin

No footpads = can get pododermatitis

Musculoskeletal features of the rabbit

delicate skeleton

Strong epaxial muscles, often fracture L7

Eyes of the rabbit

Large, lateral, with a panoramic field of vision

Rarely blink

Harderian gland (tear), creates milky secretion

Extensive orbital venous plexus

Nasolacrimal duct → small, narrow, close to tooth roots

Ears of the rabbit

Highly vascular, AV shunts

Vertical ear canal (called tragus)

Facial nerve → be aware of for surgery

Diet of a rabbit

Consumes lots of high fibre, abrasive, low-energy food

Teeth and oral cavity of the rabbit

Small mouth opening with a lingual prominence

Teeth = 4 upper incisors, 2 lower incisors, 28 total

Aradicular (no roots)

Hypsodont (high clinical crown)

Lophodont (transverse enamel ridges to grind food)

Elodont (continuously growing)

What is the structure of the rabbit GIT

Is a hindgut fermenter, with marked calcium absorption

Stomach, small intestine, sacculus rotundus, colon

Cecu 60% of GIT

What is the fusus coli in rabbits

Is a pacemaker to control peristalsis and contraction for excreting 2 tyes of feces rabbits produce

Large fibre = hard, dry feces (1-4h)

Small fibre = retropulsed into cecum, softer and lighter cecotrophs to be eaten later

What are the features of the liver in rabbits

Four lobes (caudate is narrow)

Secrete biliverdin not bilirubin in bile

Respiratory features of the rabbit

an obliagate nasal breather

Lymphatics of the rabbit

Large persistent thymus, can get thymomas

Spleen is small

Cardiovascular features of the rabbit

Small heart

Thin walled veins, easy for them to get hematomas

Kidney and urine features of the rabbit

Kidney → calcium excretion, ectopic glomeruli normal

Urine → is often cloudy from calcium carbonate monohydrate, and monium precipiates (orange-red)

Male vs. female urogenital of the rabbit

Male = open inguinal canal

Female = duplex uterus with 2 cervices, induced ovulator with fat in mesometrium

Skin of the guinea pig

Has androgen-dependent sebaceous gland, coccygeal gland (perineal sac, oily fluid and skin debris)

Hairless footpad

Skin of the chinchilla

Dense fur, long and layered colours

Hairless footpads

Musculoskeletal features of the guinea pig and chinchilla

GP = pelvic symphysis may ossify by 6 months, want to breed before then to prevent dystocia

Both have delicate skeletons and separate fibula/tibula

Nervous and senses of the chinchilla and guniea pig

Chinchilla - large eyes, big ear

Both are difficult to visualize the tympanic membrane

Diet of the guinea pig and chinchilla

Both need high fiber diet

GP = no L-gulonolactone oxidase and require vit C

C = also eats insects

Oral cavity of th guinea pig and chinchilla

Small mouth opening, with palatal ostium (growth on the palate)

Teeth = elodont, aradicular, hypsodont, only 1 set of upper incisors

Intubation complicated by fusion of soft palate to base of tongue

Guinea pig and chinchilla cecal size relative to the rabbit

Rabbit > guinea pig > chinchilla (23%)