Parasites of Dogs
and Cats
Part 2: Arthropods and Protozoa
Insects
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Trichodectes canis (Biting louse)
Linognathus setosus (Sucking louse)
Ctenocephalides (Flea)
Cuterebra (Rodent Bot Fly)
Trichodectes canis (Biting
louse)
 Found as felicola sustratus in the cat
 Cause roughened hair coat, itching and
dermatitis
 May act as intermediate host to
Dipylidium caninum
Linognathus setosus
(Sucking louse of dogs)
 Causes skin irritation, itching, dermatitis,
alopecia, anemia, roughened hair coat
 Usually transmitted by direct contact, but
all life stages may be transmitted by
fomites
 Are species specific
Ctenocephalides (Flea)
 Infest dogs and cats
 Vector for Dipylidium caninum, tularemia,
plague, etc.
 Die at temperatures below 20 F for 48
hours or at temperatures above 120 for
several days
 Over 200 species of fleas worldwide
 Severe infestations can cause anemia
Cuterebra (Rodent Bot Fly)
 Infests rodents, companion animals and
occasionally humans
 Larval stage that infests skin
 Acts as an irritant
 Migration may be fatal
 Have a cutaneous lump with a breathing hole
 Use care when extracting as crushing larva
may result in anaphylaxis
Arachnids
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Sarcoptes scabiei (Scabies)
Demodex canis (Demodectic mange)
Otodectes cynotis (Ear mites)
Cheyletiella (Walking dander mite)
Rhipicephalus sanguineus (Brown dog tick)
Dermacentor variabilis (American Dog tick)
Amblyomma americanum (Lone Star tick)
Sarcoptes Scabiei
(Scabies)
 Found as Notoedres cati in cats
 Causes intense itching, dry and
thickened skin.
 Is contagious to humans and other pets
 Mites burrow under the skin so may be
difficult to diagnose
 Diagnose through a skin scraping
 Usually have “ventral blowout”
Demodex canis
(Demodectic Mange)
 Rare in cats
 Causes areas of alopecia on head, neck,
forelimbs.
 Can be localized or generalized.
 Diagnosed with skin scraping.
 Is not contagious
 Small numbers considered normal on skin flora
 Genetic predisposition
Otodectes cynotis (Ear
mites)
 Intense pruritis of the ear canal.
 Can be found on any area of the body
 Feed on epidermal debris and are easily
transmitted
Cheyletiella (Walking
Dander mite)
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Causes mild alopecia and pruritis
May cause dermatitis in humans
Ingest keratin debris and tissue fluids
Have enormous hook like accessory
mouthparts
 Are visible to the naked eye
Rhipicephalus sanuineus
(Brown dog tick)
 Vector for canine
babesiosis and
canine
ehrlichiosis
 May cause
anemia or tick
paralysis when
found in large
numbers
Dermacentor Variabilis
(American Dog Tick)
 Feeds on small mammals but can also
feed on dogs and humans
 Vector for Rocky Mountain Spotted
Fever, tularemia, and can cause tick
paralysis in animals and humans
Anblyomma americanum
(Lone Star tick)
 Gets name from white
spot on apex of scutum
 Feeds on animals and
humans
 May be vector for Rocky
Mountain Spotted Fever
and tularemia.
 Vector of Ehrlichia
Protozoa
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Neospora caninum (Neospora)
Isopora (Coccidia)
Giardia canis (Giardia)
Toxoplasma gondii (Toxo)
Sarcocystis (Sarcocystis)
Neospora caninum
(Neospora)
 Transmitted
transplacentally or
orally
 May cause ascending
paralysis
 A type of coccidia
Isopora (Coccidia)
 Diarrhea in kittens and puppies.
 May be fatal
 One of most commonly diagnosed
protozan disorders in puppies and
kittens.
 Rarely a problem in mature animals
 Very small in comparison to other
parasites
Toxoplasma gondii (Toxo)
 May cause
transient
diarrhea in
cats
 Highly
pathogenic
to humans,
especially
fetus in
utero
Sarcocystis
 Not very
pathogenic
in cats
 Very
pathogenic
in sheep
Giardia canis (Giardia)
 Causes diarrhea
 Occur as cysts or
trophozoites in fecal
flotation.
 May also be tested
for through a snap
test now available.