Transcript RBC Morphology

Platelets, and RBC Blood
Parasites
Platelets
• Non nucleated, disk shaped elements released into blood system by
cells in bone marrow. Smaller than RBCs, large thromobocytes may
indicate disease Platelets are important in hemostasis (blood clotting)
RBC Blood Parasites
• Drying artifacts
• Refractile
• Dirofilaria immitis
• Mycoplasma haemofelis –
feline
• Hemobartonellosis or feline
infectious anemia
• Small, coccoid, rod-shaped or
ringlike, and dark
• Periphery of RBCs
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Mycoplasma hemofelis
(formerly Haemobartonella felis) is an epicellular bacterial
parasite of feline red cells that can cause hemolytic anemia. In
blood smears stained with polychrome stains, the organisms are
recognized as small blue cocci, rings, or rods on the edges or
across the faces of red cells. Stain precipitate is often mistaken
for organisms, resulting in unnecessary tetracycline
administration.
Mycoplasma hemofelis cont:
The hemolytic anemia caused by M. haemofelis is called feline
infectious anemia (FIA) and is usually regenerative in nature
(unless underlying disease suppresses the regenerative
response, e.g. Feline Leukemia Virus infection). Therefore, a
non-regenerative anemia in a cat with H. felis should not be
attributed only to M. haemofelis infection and the cat should
be further evaluated for another disease process
Parasites (cont.)
• Cytauxzoon
• Feline
Definitive microscopic diagnosis of C. felis infection relies on
identification of piroplasms in circulating erythrocytes on blood
smear; identification of large schizonts in splenic, lymph node, or
bone marrow aspirates; or identification of large schizonts on
impression smears from these organs or from the lung at necropsy.
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Babesia canis
•B. canis is endemic in southern Florida, sporadic elsewhere, especially
in the southern states; Large, pleomorphic organisms in RBC are
typical; classic paired pyriform bodies (below) are rare in this species.
• B. gibsoni is rarely seen in the USA and is found in dogs from Asian
enzootic areas; small, singular annular bodies in RBC are typical
Babesia canis
• Pups, young dogs are more susceptible
than adults, especially kennels
• Major strain differences in pathogenicity
• Rhipicephalus sanguineus transmits
transovarially, transstadially
• Incubation period 10 days-3 weeks;
transmission possible by ticks,
transplacentally or by transfusion
A three week old puppy
presented with anemia, icterus
after several littermates died
• Often concurrent with Ehrlichia canis
in a greyhound kennel
• Signs and pathogenesis are referable to regenerative hemolytic anemia.
In clinical cases, aggregates of parasitized RBC-fibrin  sludging of
capillary beds  tissue anoxia, vascular damage, especially brain, heart,
kidneys, intestines acidosis, DIC  shock and death
Diagnosis of Babesia
• Spleen, liver impression smears
of a littermate that had died. RBC
with organisms become ‘sticky’
and are taken out of circulation.
Note multiple parasites in some
RBC’s.
• Organisms were found in <1% RBC
at ‘feathered tip’ of thin smears of
capillary blood. Giemsa stain is best
• Coomb’s test is +
• Serology: IFA of > 1:40 is diagnostic
of current or previous clinical disease
Heartworm Disease
Heartworm disease or dirofilariasis is a serious and potentially
fatal disease. It is caused by a blood-borne parasite known as
Dirofilaria immitis.
Adult heartworms are found in the heart and adjacent large blood
vessels of infected dogs. Rarely, worms may be found in other
parts of the circulatory system. The female worm is 6 - 14" long
(15 - 36cm) and 1/8" wide (5mm). The male is about half the size
of the female. One dog may have as many as 300 worms present
when diagnosed.
Heartworm Disease Lifecycle
Transmission
Since transmission requires the mosquito as an intermediate host,
the disease is not spread directly from dog to dog. Spread of the
disease therefore coincides with mosquito season, which can last
year-round in many parts of the United States. The number of dogs
infected and the length of the mosquito season are directly
correlated with the incidence of heartworm disease in any given
area.
The mosquito usually bites the dog where the hair coat is thinnest.
However, having long hair certainly does not prevent a dog from
getting heartworms.
Heartworm Disease in Cats
Heartworm disease in the cat may involve some or all of the following:
Pulmonary arterial, bronchial, and alveolar disease—Heartworm Associated
Respiratory Disease (HARD)—is associated with the death of developing juvenile
worms. Cats may present with cough, dyspnea, and/or wheezing.
Death of adult heartworms (if present) can potentiate HARD signs. Sudden death
occurs in approximately 10 to 20% of diagnosed cases. Pathogenesis is unclear, but a
condition (similar to acute respiratory distress syndrome [ARDS]) caused by the release
of antigenic moieties from injured or dying adult worms is suspected.
Vomiting unrelated to eating may be present.
Pulmonary thromboemboli (fragments from dead adult worms) may cause acute
vascular and interstitial inflammatory events that lead to dyspnea and death.
Hematological abnormalities may include anemia, hyperglobulinemia, basophilia, and
eosinophilia.
Neurological signs may indicate aberrant migration of the worm to the brain, eye, or
spinal cord.
Lifecycle in Cats
Summary
• Quantifying morphologic changes
• Morphologic abnormalities
• RBCs
• Inclusions
• Parasites
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