Diagnosis of HemiLymphatic,

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Diagnosis of Hemi-Lymphatic, Eye, Urinary and
Integumentary Parasites of Dogs and Cats
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HEMIC-LYMPHATIC
Differential characteristics of Dirofilaria vs.
Dipetalonema (Knotts). Using the Knotts test
Dirofilaria is differentiated from Dipetalonema
by the traits shown. Length, width and shape of
the head are the most valuable characteristics.
Motility is checked on with a direct smear.
According to an LVMA report, Dipetalonema
incidence is low in Louisiana, on the order of 2
of microfilaria positive dogs. On filter tests
(eg .Difil), morphologic characters are similar
but a different fixation media is used than the
Knotts test and measurements are not the same.
The Knotts test is used routinely by LSU
Diagnostic Services. The Knotts test (.02) is
about 1/10 to 1/20 the cost of filter tests to
run. Blood taken in late afternoon is preferable
because of nocturnal periodicity .
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Dirofilaria microfilaria Note the slightly
tapering head (a hemisphere on a cone) and the
straight tail.
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Dipetalonema microfilaria Note the blunt head
(a hemisphere on a cylinder) and the button hook
tail (present only 1/3 of the time).
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D. Immitis and Dipetalonema microfilaria Compar
e the anterior ends and the larger size of
Dirofllaria.
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Dipetalonema anterior end -close up.
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Dipetalonema tail. Close up of buttonhook
tail.
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Dirofilaria in situ right heart In about 25 of
the cases, Dirofilaria is present but
microfilaria are not found (occult filariasis).
Radiography and clinical pathology findings are
used to diagnose such infections.
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Dirofilaria male worm. Male worms are
distinguished by their smaller size and cork
screw tail tail.
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Babesia canis. Babesiasis occurs sporadically
in dogs in Florida and other southern states
and in tropical areas in the world, but
diagnosis is difficult because organisms are
seldom detectable except in acute cases or after
splenectomy. Serology is a more accurate
diagnostic method.
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Babesia characteristics. Note that B. cania is
transmitted by the brown dog tick (a 2-3 month
L.C.). clinically affects puppies and young dogs
mainly. and causes classic haemolytic disease.
Parasitemia is notoriously low ( lt 1 RBC.s) in
acute cases. Treatment with Diaminamine aceturate
( Ganaseg. Squibb or -Berini1. Hoechst-Roussel)
has been effective at LSU .
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Canine Visceral Leishmaniasis (Leishmania
donovani. This f1age1late parasite is diagnosed
on occasion in dogs returning from endemic areas
in the Middle East or elsewhere. The parasite is
found intracellularly in macrophages in various
organs as seen in these impression smears. Note
the nucleus and kinetoplast. The disease is
highly fatal in man but dogs develop a more
chronic disease and often have cutaneous
manifestations. Dogs act as a reservoir for
Phebotomus infection in certain endemic areas.
Imported diseases such as Leishmania will likely
increase in incidence due to greater mobility of
people and animals. Several cases have been seen
at LSU .
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Cutaneous lesions in a poodle returned from
Greece. Biopsy smears may reveal organisms from
skin lesions or other organs. Serologic tests are
available at CDC through state health
departments.
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Trypanosoma cruzi This disease is endemic in
South America and Mexico where the dog often
serves as reservoir for infections in man.
Intracellular amastigotes are present in various
tissues (especially cardiac. CNS) Trypomastigotes
(seen here) may be found in the blood during the
acute disease. but seldom in chronic infections.
Giesma stain is best for blood protozoa.
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Amastigotes in cardiac musculature T. cruzi
histosection. Note nest of organisms with
distinct nucleus and kinetoplast.
16
T. cruzi distribution in U.S. A non-pathogenic
strain of T. cruzi has been recognized in
wildlife in the U.S. for some time (in the shaded
areas). Clinical cases of acute canine T. cruzi
have been reported in the Southeast since 1972.
Young animals (2 months -2 years) are presented
with acute heart failure (apparently due to
cardiac involvement) and die acutely without
treatment. An experimental Nitrofuran (Bayer) can
be tried for treatment. but 90 of cases are
fatal.
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T. cruz.i characteristics
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Hepatozoon Recent cases have been reported from
Texas. The brown dog tick vector is ingested.
Lameness (periosteal inflammation) is the often
presenting sign in chronic cases.  
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Eye Cytauxozoon Recent cases in the
Southeast of febrile hemolytic disease in cats.
RBC trophozoites, WBC schizonts. Unknown vector
(ticks?), probably Ixodes.
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Thelazia califomiemis. This eyeworm is
endemic in mountainous areas of the Western U.S.
Residing under the eyelids and in conjunctival
sac, it causes surprisingly little damage.
Eyeworms are often hidden under lids and
occasionally appear on the surface. Surgical
removal under anesthesia is indicated (20) .
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Thelazia characteristics
22
Urinary Parasites Dioctophyma renale (Giant
kidney worm) occurs in dogs and is diagnosed by
finding eggs in urine sediment . The parasite is
often unilateral on the right kidney and
literally consumes the kidney parenchyma,
entirely filling the capsule.
Ova
In situ
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Dioctophvma characteristics.
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Capillaria plica egg This non-pathogenic
nematode of the urinary bladder is sometimes
found incidentally in urine sediment.
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Capillaria plica characteristics.
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Integumentary Parasites Dracunculus insignis
This parasite is similar to Dracunculus
medenensis the fiery serpent. of man in the
Middle East. It is found in raccoons in a
sylvatic environment and rarely may infest dogs.
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Dracunculus characteristics.
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Linguatula serrats This pentastome inhabits the
nasal passages and sinuses of dogs on rare
occasion and is included here for convenience. It
attaches by anterior hooks to the mucosa and
sucks blood. Surgical removal is indicated but
spontaneous cure will occur after about 2 years.
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L. serrata adult and young adults. Note
annulated, flat appearance.  
30
Pneumonyssoides caninum. This large nasal mite is
relatively innocuous and occurs in the nasal
passages of dogs and is sometimes first noted
when crawling out around the nostrils. Ether or
other noxious chemicals may stimulate movement.
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Demodex. This is the causative agent of
Demodectic or .red. mange of dogs found in hair
follicles. Deep scrapings with a scalpel are
needed for a mineral oil or KOH preparation.
Mineral oil is easier but KOH clears debris for
easier mite identification
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Demodectic mange lesions. Dry scaley lesions
with alopecia initially start on the face around
the lips and eyes and often clears up on its own
without treatment at this stage. If the disease
progresses, a greater facial area is covered and
leg lesions may be present. Generalized mange
becomes pustular in certain individuals (immune
defect?) and is often very resistant to
treatment.
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Sarcoptes scabei var canis. Causative agent of
sarcoptic mange. Inhabit tunnels in the stratum
corneum and deep scrapings are imperative for
diagnosis. Often multiple scrapings from several
areas must be before the mite is found. Sarcoptes
is more common in Louisiana than other states.
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Sarcoptic mange lesions. Sarcoptic mange begins
on hairless areas such as the axilla or inguinal
area the callous of the elbow or the tips of the
ears. Untreated, it is quite pruritic (unlike
Demodex) and may eventually generalize (seen
here). Dog often inflict self-trauma for relief
of itching.
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Notoedres. This is the head mange mite of cats
and resembles Sarcoptes a great deal in
morphology and life history .Note the smaller
nymphal stages near the adult. Eggs may be
recovered from scrapings also, as with other
mites.
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Notoedres lesions -feline. This mite has a
predilection for the ears and head, leading to
crusty , grey alopecic lesions in the head area.
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Chyletiella lesions in a cat. This mite of dogs
and cats causes flaky dry lesions
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Chvletiella mite. Scrapings reveal a
characteristic mite with strong chewing
mouthparts
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Otodectes cyanotis The ear mite of dogs and
cats is very common. Cats get an external otitis
usually with black, dry crusty debris in the ear
.Dogs tend to have a blackish, more moist
exudate. An ear swab (wet with mineral oil) or an
ear loop is used to recover material to examine
for mites.
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Fleas Ctenocephalides felis Fleas are not
highly host specific. C. felis, ,C. canis, Pulex
irritans and even Echidnophaga of poultry may be
found on dogs or cats. Keys may be used for
identification
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Flea dermatitis lesions. Fleas can be diagnosed
by finding adults and/or flea debris (black fecal
flakes) on the skin, particularly on the tail,
head and neck areas. Certain dogs become
sensitized (as do people) and develop a
dermatitis secondary to flea bites and subsequent
scratching.
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Lice Lice are rare in dogs and cats and are
essentially a disease of neglect, in poorly
nourished, debilataed animals
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Linognathus setosus . This sucking louse is one
of three species of lice found in dogs
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Heterodoxus spininger A chewing
(biting) louse of dogs. A slide of Trichodectes
canis is not available. It is also a chewing
louse
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Canine pediculosis Lice and the nits that
attach to hairs often occur in very large numbers
on infested dogs but seldom cause serious
dermatitis lesions.
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Felicola subrostrata This is the only louse
(chewing) of cats and is rare because of cats
self-grooming. Note the groove used to attach to
hair shafts.
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Hard Ticks Heavy tick infection in a dog
(Dermacentor variabilis). Note the engorged
females (light grey) versus the engorged males
which retain their shape and color .
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Five species of hard tick are common to dogs in
the Southeastern USA as follows. Ticks often
found around the ears. Rhipicephalus
sanguineus The brown dog tick requires only
dogs for its life -f cycle. It often establishes
tenacious infestations in kennels, inside homes
or in areas frequented by dogs outside if warm
weather is present. Note the short mouthparts,
the angle in the basis capitulum and the plain
brown color of both sexes.  
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Dermacentor variabilis( The American Dog Tick)
is widespread in the Eastern US as a wood tick.
Adults parasitize dogs primarily, small animal as
larvae and nymphs. Note the characteristic ornate
scutum pattern of males and females and the
short rectangular mouth parts. Vector of Rocky
Mountain spotted fever .
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Ixodes scapularis The black-legged shoulder
tick parasitizes cattle in the adult stage but
may also attack dogs and cats. It is also a .wood
tick. acquired in field or brush. Note the very
long mouthparts, the inornate scutum. Black legs
are generally clearly visible in contrast to a
yellowish or reddish body. Vector of Lyme
disease
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Ambylomma americanum (The Lone Star Tick ) is
widespread in the Southeast in wooded, brushy
areas and often also attacks large animals or
man. Note the long mouth parts, the single ornate
spot on the female scutum and the more diffuse
ornate male markings
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Ambylomma maculatum( The Gulf Coast Tick)
occurs along the Gulf Coast and southeast
atlantic states. Note the more diffuse ornate
markings on the female scutum as compared to A.
americanum and the long mouthparts.
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Soft Ticks
Otobius megnini ( The spinous ear tick
) occurs mainly in stabled cattle and
horses in the area South West (West of Central
Texas) but may also attack dogs. Unilateral
infections are common, are extremely
irritating, and may cause severe head
shaking and tortucollis
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THE END