GI Nematodes of Small Animals Flashcards
what are the Ascarids (3)
- Toxocara canus (dog and fox)
- toxocara cati (cat)
- toxascaris leonina (dog and cat)
what are the routes of infection of toxocara canis in the dog (3)
- oral (direct) - L3 in egg
- transplacental**
- transmammary
what is the most important route of infection of Toxocara canis
transplacental
100% of pups will be infected
what is the outcome of Toxocara canis in puppies <3 months old
adult worms develop in SI which results in adult worms producing eggs
what is the outcome of infection of Toxocara canis in dogs >3-6 months old
larvae tend to arrest in tissues
no adults, arrested larval development
ALD consequence of immune response in older animal
how long does transmammary transmission occur in Toxocara canis in the dog
~5 weeks
at what age is the highest level of infection of Toxocara canis in puppies
<6 months old
when are worms expelled in puppies in Toxocara canis
expelled by 6-8 months of age
when are Toxocara canis not susceptible to anthelmintics
arrested L3
what are the clinical signs of Toxocara canis infection in puppies
enteral phase:
- pot bellied pups
- failure to thrive (starved, stunted)
what is the main principle of Toxocara canis treatment
prevent environmental contamination with eggs
what is the PPP of Toxocara canis
min 16 days
when would you start treatment of Toxocara canis
start before parasite lays eggs and continue to remove milk acquired infection (5 weeks)
treat at around 2 week period before eggs are laid into environment
treat bitch at the same time
when and what would you treat a bitch with Toxocara canis
high dose fenbendazole
3 weeks pre partum and 2 days post partum
what is the PPP of toxocara cati
~8 weeks
what are the routes of infection of toxocara cati
- transmammary
- direct route – migration
- paratenic route (rodents ingested)
is there transplacental infection with toxocara cati
no
which is infective –> embryonated, unembryonated and larvated toxocara cati and canis eggs
embryonated and larvated egg is infective
how do toxocara cati and canis eggs persist in the environment
sticky and resistent
survive years in environment
are toxocara canis and cati eggs diagnostic
yes
sculptured egg shell
are toxocara cati and canis zoonotic
yes can infect humans
eggs hatch and migrating larvae cause ocular and visceral disease
how is toxascaris leonina transmitted
direct, egg containing L3
is there a migratory phase in toxascaris leionina
no
how can toxascaris leonina be distinguished from T. canis
toxascaris leonina is smooth shelled
what is the PPP of toxascaris leonina
~11 weeks
what are strongyloidea
hookworms
what are the hookworms (4)
- ancylostoma caninum (dog)
- a. braziliense (dog and cat)
- a. tubaeforme (cat)
- uncinaria stenocephala (dog, cat and fox in UK)
what are the physical features of hookworms
1-3cm, stout, hooked
where is the predilection site of hookworms
small intestine
what stage are hookworms infective
L3
taken up from environment (ingested or migrate into lower limbs)
what is the lifecycle of ancylostoma caninum
- immature worms swallowed or immature worms penetrate skin, ALD immature worms can remain dormant in skeletal muscle
- immature worms migrate to mammary glands and infect puppies through milk
- adults present as male and females –> produce eggs which are excreted into feces
- eggs in feces from 2-4 weeks after infection
- immature worms developing in eggs
- development of egg through emergence of infective larva takes about 1 week
what is the PPP of ancyclostoma caninum
14-21 days
how long does it take for ancylostoma caninum to develop from L1-L3 in the environment
5 days
how does arrested larval development ALD
larvae that migrate via the lungs can arrest as L3 in skeletal muscle
can emerge from arrest after infection when immunocompromised or stressed
is the there transplacental infection of a. caninum
no
transmammary is most important
what is the pathogenesis of A. caninum
simple hemorrhage
immature and adult worms feed
each female worm ~50-`00 ul blood per day
worms change feeding sites up to 6 times per day
what are the clinical signs of A. caninum in young animals
severe acute hemorrhagic anemia (maybe bloody diarrhea)
what are the clinical signs of A. caninum in older animals
chronic hemorrhagic anemia
respiratory signs due to larval damage
where do A. caninum develop
warmer climates (larval development requirement)
what are the two sources of A. caninum
- transmammary
- percutaneous/oral from environemt
how are A. caninum diagnosed (3)
- clinical signs
- history
- fecal egg count (pathogenic in prepatent phase) fecund (typical strongyle egg)
is this egg diagnostically significant
no its not
a. caninum
can’t tell what species
how is A. caninum controlled (2)
- chemotherapy (3 monthly)
- benzimidazoles
- ivermectin/moxidectin
- fenbendazole in pregnant bitch - clean dry bedding, earth or grass runs support survival of L3
how does the vaccine against hookworms work
stimulate an antibodh response to nematodes digestive enzymes
Ab bind to microvillar surface of worm gut
inhibits digestion of blood
worms starve – less fecund, shorter, reduce anemia in host
how is uncinaria stenocephala transmitted
oral infection (sheated L3)
no percutaneous or transmammary infection
what is the pathology of uncinaria stenocephala (3)
- not a voracious blood sucker: protein losing enteropathy
- skin infection not effective: L3 penetrate skin but die
- hypersensitivity responseL pedal dermatitis
how is uncinaria stenocephala diagnosed
eggs in feces
similar to Ancylostoma but slightly larger
differential diagnosis requires larval culture
how can Ancylostoma and Uncinaria adults be distinguished
Ancylostoma has teeth
uncinaria has cutting plates
where is uncinaria stenocephala most prevelant
in working dogs (farm dogs)
what are whipworms
trichuroidea
trichuris
what is the life cycle of trichuris (10)
- eggs consumed
- adults embedded into wall of dog’s cecum and colon
- adult release eggs
- egg in feces 74-90 days after infection
- L1 developing in egg – resistant
- ingested
- plugs digested L1 released
- penetrates mucosal glands
- larvae develops inside egg in topsoil (taking 9-26 days to become infective) –> L2 –> L3 –> L4
- adult worms in intestine
what is the pathology of trichuris vulpis (3)
- usually asymptomatic
- occasionally diptheritic enteritis and hemorrhagic colitis
- watery diarrhea +/- blood
how is trichuris vulpis diagnosed
eggs in feces
diagnostically significant
lemon shaped eggs with polar plugs at ends
what is the PPP of trichuris
6-12 weeks
how is trichuris treated
benzimidazoles
probenzimidazoles
how is trichuris controlled
clean, dry, bedding, earth or grass runs –> disinfect, heat or steam clean areas to remove long-lived eggs
