Toxocara canis:

Identification of the adult

Nematode

Roundworm

Up to 18cm

3 prominent lips

Prominant cervical alae

Opaque, milky, rubbery

Toxocara canis:

Zoonotic potential

Visceral LM

Neural LM

Ocular LM

Kids infected by ingesting contaminated dirt/pet hair.

Ova viable up to 7 years.

Toxocara canis:

Life Cycle in pups less than 6 months old

Ova w/developed larva ingested.

Larva hatches, penetrates small bowel.

Venous circulation.

Liver

Heart

Lungs

Penetrate alveoli, develop to L-4

Migrate up airway to pharynx.

Coughed & swallowed.

Adults produce ova.

Prepatent period = 4-5wks

Toxocara canis:

Life Cycle in dogs over 6 months old

Dogs have immunity from past exposure.

Larvae pass from SI to liver & lungs.

Lodge in somatic tissue & encyst.

Stress & immunosuppression can trigger patency.

Toxocara canis:

Life Cycle in pregnant dogs

Dormant larvae activated during last 1/3 of gestation.

Travel to mom's SI and pups.

Enter pup's circulation transplacentally.

Pass through liver & lungs.

Adult worms in SI 2-3wks post-partum.

Patent 3 wks post-partum.

Transmammary transmission also.

Toxocara canis:

Clinical signs

Most light infections are asymptomatic.

Up to 85% pups infected; 4% adult dogs.

Classic signs: pot belly, rough coat, diarrhea, vomiting, obstipation, depression, seizures, coma.

Verminous pneumonia may cause death in heavily prenatally-infected pups.

Toxocara canis

fecal float ID:

rough outer shell, smooth inner surface.

Toxocara cati (mystax)

Adult Identification

Transmission

Zoonotic Potential

Nematode

Cat Roundworm

Up to 10cm

3 lips

cervical alae

NO transplacental transmission.

Parenteric hosts common: earthworm, mouse, chicken, dog, cockroach, man

Visceral Larval Migrans.

Toxocara cati (mystax):

Life Cycle

Ova ingested.

Larvae hatch, enter circulation from SI.

Liver - heart- lungs.

Develop to L-3.

Migrate up airway, swallowed.

Larvae penetrate wall of stomach, molt to L-4.

Return to lumen of stomach.

Pass to SI.

Develop to adult.

Patency in 6wks.

Toxocara cati (mystax):

Clinical signs

Light loads = asymptomatic

Classic signs: pot belly, rough coat, diarrhea, vomiting, obstipation, depression, seizures, coma, verminous pneumonia.

Toxocara cati:

Fecal float.

Rough outside, smooth inside.

Smaller than T. canis.

Toxascaris leonina:

Adult identification

Nematode

Arrowhead Worm

Hosts: canids, felids

Up to 10cm

Males abursate

3 lips, cervical alae

Toxascaris leonina:

Life Cycle

Ova passed unembryonated in feces.

Develop into L-3

Ingested parenteric host (w/ova/larva)

Larva penetrate wall of SI

Molt

Prepatent in 7-10wks.

NO transmammary, transplacental transmission.

Toxascaris leonina:

Clinical signs

Least pathogenic ascarid of pets.

Limited larval migrans

No transplacental/transmammary transmission.

Moderate infections may cause intestinal pain/irritation.

Superinfections unusual, can cause acute death.

Toxascaris leonina:

Fecal float.

Sooth outside, rough inside.

Baylisascaris procyonis:

General facts

Baylisascaris procyonis:

Nematode

Raccoon = very common host.

Rodents = parentenic hosts.

Dog, squirrels, man = aberrant hosts.

Most common cause of clinical larval migrans (neural, visceral, ocular).

Baylisascaris procyonis:

Zoonotic potential

OLM, VLM, NLM.

Most common clinical cause of LM.

Baylisascaris procyonis:

Fecal float.

Ellipsoidal, brown, contain large single-celled embryo.

Thick shell w/finely granular surface.

Smaller than Toxocara spp.

Ancylostoma caninum

Ancylostoma tubaeforme

Ancylostoma braziliense

Uncinaria Spp.

General Info:

Nematode

Hookworm

Prefers tropical/subtropical/warm temperate zones.

6-12mm long

Large, wide buccal capsule w/cutting plates/teeth.

Uncinaria approaching distinction - less robust life cycle + anthelminthics.

Ancylostoma:

Zoonotic Potential

CLM (creeping eruptions).

Eosinophilic enteritis.

Ancylostoma:

Clinical Signs

Severe anemia in pups/kittens.

Pale gums, weakness, dark tarry stool, low PCV/HCT.

Death.

Ancylostoma:

Free-Living Phase

Typical Strongyle Ova (TSO) in feces.

Hatch in hours to days.

L-1 have rhabditiform esophagus; feeds on organic material & bacteria.

Molts to L-2, L-3.

L-3 infective, no longer feeds outdoors.

Infection by ingestion or skin penetration.

Ancylostoma:

Parasitic Phase

ORAL

Ingestion of L-3.

Travels to SI, enters mucosal crypts.

Molts to L-4, enter lumen; forms buccal capsule & feeds.

Molts to L-5, reproduce.

Ova in feces.

PERCUTANEOUS

L-3 penetrates skin.

Burrows to venules, through right heart, to lungs.

Break into alveoli.

Migrate up airway; swallowed.

Molt to L-5, reproduce.

Ova in feces.

Ancylostoma:

More Parasitic possibilities

SOMATIC Larva - linger in somatic tissues (arrested).

PRENATAL Route - dormant larvae in mom activated by pregnancy. Transplacental.

TRANSMAMMARY Route - A. caninum.

INTESTINAL Repopulation - arrested larvae in tissues activated by clearing of intestines by anthelminthics, migrate to SI to repopulate.

Ancylostoma:

Fecal float or direct smear.

TSO

Trichuris vulpis:

General Info

Whipworm

Slender neck, thick posterior end.

Adult = 45-75mm

Have a mouth spear to slash tissue with as is weave itself in.

Feeds on blood & mucosa.

Trichuris vulpis:

Clinical Signs

Trichuris vulpis:

Fecal float

Trichuris vulpis:

Life Cycle

Adults live in SI.

Oviparous ova.

Ova passed in feces (survive months to years)

Develop to larva within ova.

Ingested by dog.

Digestive fluids in dog digest end plug, free larvae.

Larvae enter crypts of Lieberkuhn.

Migrate to liver, molt 3x to L-3, then adult.

prepatent period = 70-107 days.

Strongyloides:

General info

Dog & man - S. stercoralis.

Dog - S. canis.

Cat - S. tumefaciens.

Intestinal Threadworm.

Nematode.

Prefers warm, humid climates, but common in kennels/pet stores.

Small - 2.2 mm.

NO parasitic male.

Baermann Funnel

For collecting nematodes from soil samples.

Strongyloides:

Genetics

Parasitic female is triploid.

She produces triploid, diploid, haploid offspring:

Parasitic female = triploid.

Free-living females = diploid.

Free-living males = haploid.

Male + free-living female = triploid parasitic offspring.

Parasitic females don't need males to reproduce.

Strongyloides:

Life Cycle

Vertebrate hosts infected mostly by skin penetration by L-3 triploid females.

Larvae penetrate a venule, carried to lungs, alveoli. 

Migrate up pharynx, swallowed, pass to SI.

Develop to adult parasitic females.

Triploid females produce haploid male & diploid female ovoviviparous ova, passed in feces.

In dogs only: ova hatch to L-1 before being passed.

Strongyloides:

Clinical Signs

Other Info

Clinical Signs: pruritis, coughing, anorexia, weight loss, conjunctivitis, watery diarrhea w/blood and mucus.

Verminous pneumonia.

Rash at site of skin penetration.

Autoinfection possible in man, but only possible in immunocompromised dogs.

NO prenatal infection in dog or cat, but yes in other species.

Strongyloides:

Fresh fecal float (larva in dog, ova in other species).

Baermann Funnel to collect larvae.

Dirofilaria immitis:

General Info

Filarial Nematode.

Heartworm.

Definitive host: DOG

rarely vats, walruses, man.

Adults live in right heart & pulmonary artery.

Females 9-12 inches.

Males 6-7.5 inches; abursate, corkscrew tail, w/spicules.

Gram-negative, Rickettsia-like organism that lives intracellularly in all stages of filarial nematode life cycles (inc. dirofilaria).

Treating bacteria can slow/stop female worm reproduction.

Allows early diagnosis (blood seriologic tests) & treatment.

Dirofilaria immitis:

Life Cycle

Adults in right ventricle & right pulmonary artery.

Females give birth to viviparous L-1 (microfilaria).

Microfilaria must be ingested by intermediate host (mosquito - 14 known vectors) & develop from L-1 to L-3 in the mosquito's malpighian tubules.

L-3's deposited on skin when mosquito feeds, crawl into wound.

Molt to L-4, migrate to heart. 

Molt to L-5 in pulmonary artery.

Patency = 190 days (4-month migration).

Dirofilaria immitis:

Clinical signs

Congestive Heart Failure:

Fainting

Weakness

Shortness of breath

Abdominal enlargement w/fluid

Coughing

Vomiting

Weight loss

Wasting.

Fewer than 25 worms often asymptomatic.

Dirofilaria immitis:

Diagnosis Techniques

KNOTT's Test: mix blood + formalin, spin, pour off sup, mix w/New Methylene Blue, put on slide, read at 100x looking for L-1.

MILLIPORE FILTER: mix blood + sodium citrate lysing solution, force through a filter, stain w/New Methylene Blue, examine filter under microscope for L-1.

FRESH BLOOD SMEAR: good if L-1 numbers are high, easy, quick - drop of blood + coverslip, look for motile L-1 or RBC.

BUFFY COAT EXAM: microhematocrit tube spun, examine white buffy coat btwn plasma & RBC for "medusa's head" w/wiggling worms waving in plasma.

ANTIGEN tests: measure reproductive antigens of females - very specific, but not very sensitive - must have more than 4-5 worms, may not detect male worms, will test positive for dogs that have cleared a hwt infection.

BEST: use both Knott's test & antigen test to get most accurate results.

Dirofilaria immitis:

Other diagnostic tests

Radiographs

ECG & echocardiogram

Lab

Ultrasound

MRI

Dirofilaria immitis:

Control Measures

Keep mosquitos away from dog.

Keep dog away from mosquitos.

Prevent infection w/drugs.

Dirofilaria immitis:

incidence in cats

Only common in endemic areas.

Cat = aberrant host.

Result - 

Heartworm Associated Respiratory Disease (HARD):

Respiratory signs w/asthma or vomiting.

Cats & man not patent - can't give L-1 back to mosquito to complete the life cycle.

Dipetalonema:

General Info

Filarial nematode like Dirofilaria.

NON-PATHOGENIC.

Small adults - female = 1 inch, male = 1/2 inch.

Live in SQ space.

Intermediate host = flea.

Definitive host = dog - microfilaria in blood - must be differentiated from dirofilaria.

Spirocerca lupi:

General Info

Esophogeal Worm.

Intermediate host = dung beetle.

Definitive host = dog.

Found in anterior GI tract.  1.25-3.5 inches long, red in color.

May cause cancer from chronic infections.

Spirocerca lupi:

Life Cycle

Larva develop to L-3 in dung beetle.

Beetle eaten by dog or chicken (transport host).

Dog infected by eating beetle or chicken.

Larva penetrates into gastric artery, migrates to aorta, lodges in esophagus, develops to adult.

May cause esophageal obstruction/stricture or cancer.

Spirocera lupi:

Difficult diagnosis - adults pass few ova, ova don't float in fecal solutions.

Canine lungworm.

Coyotes have osleri; dogs have hirthi.

Osleri make granulomas in trachea/in lung tissue, causes difficulty breathing.

Hirthi found in lung tissue, is fairly common.  Rarely causes clinical signs.

Prepatent period = 4 months.

Filaroides:

Life Cycle

Adults live in nodules near tracheal bifurcation. 

L-1 larva passed in tracheal secretions, coughed up, regurgitated up, passed in feces.

L-1 INFECTIVE to dogs.

Filaroides:

ZnSO4 fecal float.

Bronchoscopy exam.

Tracheal secretion collection.

Capillaria aerophila

Capillaria plica:

General Info

Parentenic host - earthworm.

Hosts - dog, cat, fox eat earthworm.

Lives in tracheal mucus membranes (aerophila) or urinary bladder (plica).

Ova passed in feces or airway secretions (aerophia) or in urine (plica).

Capillaria:

Bipolar, asymmetrical, golden ova that looks like Trichuris in feces, secretions, urine.

Aleurostrongylus:

General Info

Nematode

Feline Lungworm

Commonly seen in PNW, esp. along the coast/rivers.

Mouse/bird = paratenic hosts.

Intermediate host = snail, slug.

Cat = definitive host, eats snail, slug, mouse, bird.

Aleurostrongylus:

Life Cycle

L-1 passed in feces/saliva.

ingested by snail/slug.

Develops to L-3.

Cat eats snail/slug.

Cat eats bird/mouse that has eaten snail/slug.

Prepatent period = 5-6 wks.

Aleurostrongylus:

Fecal float - crooked tail L-1.

Baermann Funnel Test.

Saliva sample.

Feces can look clay-like & gray.

Control - keep cats from preying on mice, birds, snails, slugs.

Dioctophyme renale:

General info

Giant Kidney Worm

Definitive hosts: dog, swine, sometimes man.

Intermediate host: annelid worm (ext parasite of crayfish).

Paratenic hosts: crayfish w/annelid worm, catfish that has eaten crayfish/annelid worm.

Female 1 meter long, male 10 inches long.

Male has bell-shaped bursa & 1 spicule.

Dioctophyme renale:

Life Cycle

Ova passed in urine in/near water.

Ingested by annelid worm.

Molts to L-3.

Annelid worm/worm + crayfish/catfish that ate them ingested by definitive host.

Adult found in renal pelvis or free in abdomen.

1 worm in each kidney will destroy both kidneys, kill host in 3-4 months.

Dioctophyme renale:

Diagnosis & control

Find brown, thick-shelled ova w/bipolar plugs in urine, find worm in necrotic kidney.

Tx = removal of the affected kidney.

Control = don't feed/allow consumption of raw/undercooked fish.

Thelazia californiensis:

General Info

Nematode

Eyelid worm

LIves under 3rd eyelid/nictitans.

Seen along Pacific coast.

Reservoir host - deer

Intermediate host - face flies.

Tx = anesthetize eye, remove worms w/forceps.

Dracunculus insignis:

General info

Nematode

Intermediate host = copepod (micro water insect)

Definitive host = raccoons, dogs

Migrates to foot/distal extremity, creates open sore. Lesion burns.  Host puts foot in cool water.  Dracunculus pokes head out of wound & spews ova (vulva near head) into water.

Copepod ingests ova.

Dog, raccoon ingest copepod when drinking water.

Develops SQ, migrates to extremity.

Like DRACUNCULUS MEDIENSIS - human guinea worm.

Physaloptera sp.:

General info

Stomach worm.

Intermediate host - beetle.

Definitive host - dog, cat, wild canids & felids.

Larvated ova shed in feces.

Causes gastritis, vomiting.

Physaloptera sp.

Fecal float

ID of adults in vomitus

Nanophyetus salmincola:

General Info

Trematode - rickettsia

Salmon Poisoning of Dogs (SPD)

Intermediate host = water snail

Transport host = salmonids

Definitive host = dog, coyote, bear, fox, mink, raccoon.

Limited by range of water snail - N. California to S. British Columbia.

Cooking kills fluke & rickettsia, but smoking, drying, curing might not.

Nanophyetus salmincola:

Life Cycle

Operculate fluke ova passed in feces near water.

Develop ~3mo. in water.

Miracidium hatches, swims by cilia to water snail.

penetrates snail, moves to green gland.

Develops to sporocyst.

Develops to redia.

Asexually form many cercaria.

Cercaria released, penetrate salmonid fish, encyst as metacercaria (can survive death of the fish).

Fish ingested.

Adults sexually reproduce, pass ova in feces.

Nanophyetus salmincola:

Clinical signs

Incubation period = 5-21 days.

Fever to 107 degrees; may drop later in disease to below normal.

Vomiting, diarrhea that is profuse, malodorous, w/bloody metallic smell.

Lymph node enlargement.

Depression.

Anorexia.

Shock.

Death in 2 wks in untreated.

WILD host show few, if any, signs.

Nanophyetus salmincola:

Find ova in feces - direct fecal, stained w/New Methylene Blue.

Operculate, reticulate, golden colored.  Don't float.

Cytology of lymph node.

Most diagnoses made on basis of characteristic clinical signs & response to therapy.

Tetracycline:

Dangers in Tx of SPD

Animals must be older than 6mo to treat w/tetracycline.

Causes permanent staining & pitting of developing enamel on permanent teeth.

Dipilidium caninum:

General Info

Cestode

Flea Tapeworm

Intermediate host = flea, sometimes dog louse. Cysticercoids in arthropod.

Definitive host = dog, cat, man (aberrant)

Nonpathogenic in moderate numbers.

Pepatent period = 4 wks.

Dipylidium caninum:

Life Cycle

Proglottids w/ova packed in egg packets passed in feces.

Proglottid breaks up over time.

Larval flea feeds on organic debris & ingests ova.

Hexacanth larvae penetrate midgut of flea, forms cysticercoid in body cavity.

Flea matures.

Dog/cat ingests flea/flea part.

Immature tape attaches to SI, matures to adulthood.

Gravid proglottids break free & pass in feces.

Dipylidium caninum:

Fecal floats don't yield proglottids or ova packets.

Dx based on seeing proglottids in feces.

Control - treat for fleas (pet + env.)

Taenia pisiformis:

General Info

Cestode

Rabbit Tapeworm

Intermediate host = rabbit

Definitive host = dogs & canids

6-10 inches, up to 30 inches long.

Asymptomatic

Taenia pisiformis:

Life Cycle

Adults in SI of dog.  Pass proglittods w/ova in feces.

Ova ingested by rabbits.

Larva migrates from intestine to liver, forms cysticercus (bladder worm).

Causes condemnation of rabbit carcass if found on inspection of meat.

Dog ingests rabbit w/cysticercus.

Patent in 2 months.

Taenia pisiformis:

Ova look like Echinococcus granulosus.  All taenia infections MUST be considered possible publich health hazards.

Ova have 3 pr of hooks.

Echinococcus granulosus:

General Info

Cestode

Hydatid disease/hydatid worm.

Intermediate host = herbivore (sheep, caribou, moose, deer, man (aberrant)

Definitive host = carnivore (dog, coyote, fox, wolf)

Hydatid cyst grows large, causing space-occupying symptoms.  

Tx = surgical removal.

Rupture can cause anaphylaxis.

Cysts usually in liver, brain, lung, bone, kidneys, etc.

Echinococcus:

Life Cycle

Small adult lives in SI of carnivore.

Ova passed in feces.

Ova ingested by grazing sheep.

Hexacanth larva hatches & migrates to liver & lungs.

Develops into hydatid cyst in 4-5 months.

Cyst ingested by carnivore by predation.

Patent in 2 wks.

Man infected by petting dog w/ova on hair, eating contaminated veggies/water, other unsanitary means.

Echinococcus:

Identical to Taenia ova.

Diagnosis - administer purgative and inspect worms.  Echinococcus is very small.  Shape & distribution of suckers can be used to ID.

Casoni test can be used in people to test for hydatid disease - inject small amount of hydatid fluid and measure reaction.

Giardia canis:

General Info

Protozoa.

Montezuma's Revenge.

Hosts - dog, cat. man, beaver, calves, goats, caged birds, rodents.

Intermittent bouts of prolonged diarrhea common. 

Colitis common.

Can be asymptomatic carrier; stress triggers disease.

Giardia:

Life Cycle

Direct life cycle.

Feeding stage = trophozoite - tear-drop shape w/concave ventrum to form sucker.

Divides by binary fission.

Resistant cyst stage as it passes into bowel.

Giardia:

Clinical Signs

Irritation of SI lining.

Gathers & covers absorptive surface of the bowel, preventing food from being digested properly.

Undigested fats & carbs flow into colon - bacteria here bloom b/c so much to feed on.  Causes light colored, pasty, fetid feces.

SIgns similar to colitis: straining to defecate, flatulence, scant & frequent stools, blood & mucus in stools, fluid & protein loss, weakness, vomiting, depression.

Giardia cyst:

ZnSO4 w/Lugol's iodine = best screen for giardia. 65% accurate w/1 test.  Need 3 separate tests for good accuracy.

Giardia ELISA has good accuracy.  Good to confirm ZnSO4 diagnosis.

Cystisospora sp.:

General Info

Protozoa

Coccidia/Coccidiosis

Hosts - dog, cat.

Species-specific.

Not a Zoonosis.

Usually seen w/ crowding/filthy conditions.

Oocysts resistant in environment.

Cystisospora:

Life Cycle

Direct life cycle.

Epithelial cells in gut invaded by schizonts.  Sexual & asexual repro.  Gut cell ruptures after sexual repro.

Unsporulated oocyst passes with feces.

Sporulates over 1-5 days.

3-11 days to patency.

Cystisospora:

Clinical signs

Pathology caused by ruptured gut cells in host.

Amount of disease influenced by:

The level of villus involved.

The # of asexual generations.

Host's health, age, immune status, presence of other parasites/disease processes.

Signs:

tan/mucoid/bloody diarrhea.

Can cause prolapsed rectum in pups & kittens.

Cystisospora:

Fecal float

Smaller oocysts more pathogenic.

Trichomonas foetus:

General Info

Newly emerging protozoan in cattery cats, abyssinians, purebreds.

Identical to T. suis (swine) and GIT (cattle).

Carriers common.

Trichomonas foetus:

Wet Mount: look for motile organisms.

Pouch test: plastic pouch w/media to grow thrichomonas.

Trichomonas PCR: Antech/Idexx.  Expensive, time-consuming.  

Sarcocystis spp.:

General Info

Usuall nonpathogenic.

Intermediate host = herbivore (eosinophilic myositis in food animals)

Definitive host = rarely dogs & cats.

Sarcocystis spp.

Banana-shaped sporocysts on fecal float.

Can be caused by raw meat diets.

Cryptosporidium parvum:

General Info

Common cause of diarrhea in young ruminants.

Sometimes causes diarrhea in dogs & cats, man.

Oocysts sporulated in feces.

Autoinfection possible.

Feces infective right away.

Cryptosporidium parvum:

Easily overlooked on fecal float b/c they're so small.

Sheather's Sugar Solution gives oocysts a reddish color.

ELISA snap test available.

Toxoplasma gondii:

General info

Definitive host/Reservoir host = cat.

Most warm blooded animals can be intermediate host.

Obligate intracellular parasite.

Usually subclinical - animals don't get sick.

ZOONOSIS - abortion, still-birth, birth defects, retardation in human & animal hosts.

Toxoplasma gondii:

Life Cycle

Cat eats raw meat infected with tissue cysts.

Intestinal Phase

Extraintestinal Phase - cysts may occur in brain, muscles, heart, visceral organs, etc.

Transplacental Phase - can cause placentitis & fetal infection.

Main means of transmission = handling raw meat.

Avoid raw meat & cat feces especially when pregnant.

Toxoplasma oocysts:

Finding oocysts in feces is rare.

Serologic tests using paired serum most accurate.

***Any oocyst in cat feces that is 10-12 microns should be treated as if toxoplasma***

Babesia canis:

General Info

Canine Piroplasmosis.

Seen in racing grayhounds in the south.

Signs: high fever, anemia, jaundice, depression.

Life Cycle: protozoan RBC parasite.  Transmitted by brown dog tick, other ticks.

Trophozoites infect RBCs, replicate, infect other RBCs.

Recovered dogs are persistant carriers.

Neospora caninum:

General Info

Tissue systs, tachyzoites, oocysts in the dog.

Transmitted transplacentally & orally.

May cause ascending paralyisis & rigid contraction of muscles, necrosis, inflammation, encephalomyelitis, hepatitis, myocarditis, myositis, etc.

Diagnosis = clinical signs & histology.

Definitive host = dog.