Download Anemia, Thrombocytes, and Blood Parasites

Anemia, Thrombocytes,
and Blood Parasites
Clinical Pathology
Autoimmune Hemolytic Anemia
(AIHA)
• Antibodies directed against RBC membrane
antigens and Ab- coated RBC’s are removed from
circulation.
• Hemolytic process results in varying degrees of
anemia depending on antibody type, speed of
development, and duration of the disease process.
• Female dogs are more commonly affected than
males.
• Certain breed predispositions include: Poodles,
Cocker Spaniels, Terriers, Old English Sheepdogs,
Lhasa Apsos, and Shih Tzus.
• Rare in cats, usually associated with FeLv or
Hemobartonella.
AIHA continued
• The spleen is the primary site for removal
of RBC’s coated with IgG while the liver
removes RBC’s coated with IgM.
• Onset of anemia may be acute or gradual.
• Complications:
• DIC
• Pulmonary Thromboembolism
Causes of AIHA
• Primary AIHA: autoantibodies directed
against RBC’s with no underlying disorder,
most common.
• May occur in association with immune
mediated thrombocytopenia.
• Secondary AIHA: Ab production initiated
by drugs, vaccines, infectious diseases
and neoplastic disorders.
Diagnosis
• History and Physical Exam
• CBC
• Regeneration
• Spherocytes
• Autoagglutination
• Anemia (PCV<20%)
• Coombs Test
• Splenomegaly and Hepatomegaly seen on
radiographs.
Therapy for AIHA
• Corticosteriods:
• Reduces clearance of Ab coated RBC’s by
inhibiting function of macrophages in the spleen
and liver.
• Prednisone at dose of 2 mg/kg/day divided
BID.
• Blood transfusions in life-threatening situations.
• Other immunosuppressive drugs
• Cyclophosamide
• Azathioprine
• Cyclosporine
• Splenectomy
• Indicated if anemia is nonresponsive to
immunosuppressive drugs.
Classification of Nonregenerative
Anemia
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Primary failure of erythropoiesis
Secondary failure of erythropoiesis
Nuclear maturation defects
Hemoglobin synthesis defects
Aplastic anemia
Marrow infiltration
Primary Failure of Erythropoiesis
• Patient stops producing red blood cells
• Circulating blood has few reticulocytes,
normocytic, normochromatic RBC’s.
• Bone marrow normal except for hypoplasia
of erythroblasts.
• May be immune-related or caused by
certain drugs or neoplasia.
Secondary Failure of
Erythropoiesis
• Caused by a chronic disorder such as
renal failure, liver disease, inflammatory
disease, neoplasia, and endocrine
disorders.
• Bone marrow is normal or has slight
erythroid hypoplasia.
Nuclear Maturation Defects
• Associated with folate and B12 deficiency
(rare).
• Macrocytic, normochromic anemia due to
a defect in DNA synthesis.
• Megablastic erythroblasts in bone marrow.
• Check serum folate and supplementation
is the cure.
Hemoglobin Synthesis Defect
• Primary associated with iron deficiency.
• Microcytic, hypochromic anemia due to decrease Hb
production in individual cells.
• Iron deficiency can result from a poor diet, poor
absorption, and following an incident of marked blood
loss.
Aplastic Anemia
• Bone marrow failure due to marrow necrosis and/or
inflammation.
• Bone marrow is acellular or hypocellular resulting
in anemia, thrombocytopenia, and leukopenia.
• Causes:
• Ehrlichia canis
• FeLv
• Parvovirus
• Estrogen
• Phenylbutazone
• Radiation
• Chemotherapy
Marrow Infiltration
• Neoplasia: crowding of marrow elements
with neoplastic cells.
• Myelofibrosis: hypoplasia of marrow
elements with replacement by collagen
(sequel to damaged marrow).
• Osteopetrosis: inherited disorder with
increased bone density.
Thrombocyte = Platelets
• Platelets are produced by fragmentation of
megakaryocytes in bone marrow
• 150-200 platelets are formed from one
megakaryocyte.
• Lifespan: 7-10 days
• Normal count: 200,000 – 500,000/mm3
• Thrombocytopenia- most common cause of
bleeding in dogs.
• Normal hemostatis depends on adequate platelet
number and function
• Important role in primary hemostatis involving
interaction between injured blood vessel wall and
platelets
When Thrombocytopenia is found
• Make sure you had a good stick, if not recollect
sample from a large peripheral vein.
• If yes, perform coagulation test, CBC, tick panel.
• If those are normal, then check bone marrow
Immune Mediated
Thrombocytocenia
• Most common in middle-aged female
dogs, less common in cats.
• May be primary cause similar to AIHA.
• Secondary causes are drugs, viruses,
immune complexed, infectious disease,
etc.
Coagulopathy
• Test platelets
• Platelet count
• Bleeding time
• Test Coagulation Factors
• Activated Clotting Time (ACT)
• Activated Partial Thromboplastin Time
(PTT)
• Prothrombin Time (PT)
Disorders of Blood Coagulation
Factors
• Von Willebrand disease (vWD): factor VIII
decreased.
• An additional portion of the molecule which is
important in platelet function is decreased or
absent.
• Abnormal platelet function.
• Increased mucosal surface bleeding time.
• Excessive surgical bleeding.
• Chronic, low grade bleeding possible.
• PTT may be mildly prolonged
• Antigen test
Buccal Mucosal Bleeding Time
• Normal clotting time 2-4 minutes
• Platelet dysfunction at 10-12 minutes
• Begin timing immediately after making cut.
Wound should not be wiped or disturbed
until it has clotted.
Cuticle Bleeding Time
• Normal time is 2-8 minutes
• Begin timing at the time the nail is cut.
Discrete drops of blood should fall from
wound. A steady stream indicates that the
wound is too far in the cuticle.
Equine Infectious Anemia (EIA)
• Contagious and potentially fatal viral disease in
horses.
• No vaccine or treatment exists.
• Transmitted by biting insects such as horseflies
and deerflies.
• Can also be transmitted by dirty needles.
• Also called Swamp Fever
• Two stages:
• Acute
• Develops severe, acute signs within 2-3
weeks. Signs occur rapidly and cause only a
slight increase in temperature, 30% of
horses die at this stage
• Chronic
• Temperature > 105˚ F
Clinical Signs of EIA
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Petechial hemorrhage
Depression
Weight loss
Edema in legs and abdomen
Anemia
Coggins Test
• Checks for antibodies to the
virus
• Positive Test Options
• 1. Retest
• 2. Euthanize
• 3. Sale for immediate
slaughter
• 4. Lifetime Quarantine
Texas Law and Reactors
• Retest in 30 days at TVMDL
• Official reactors are permanently marked
by using a National Uniforms Code
branded on the left shoulder or neck.
• Quarantine should be at least 200 years
from other equine
• All exposed equines must be tested
Common Blood Parasites you should know
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Ehrlichia platys
• Brown dog tick transmits
Erhlichia canis
• Common in TX
• Transmitted by Brown dog tick
• 3 stages of disease
• (acute, subclinical, and chronic)
Hemobartonella felis
• FIA (feline infectious anemia)
• Rickettsial organism
• Transmitted by fleas, ticks, blood transfusions, queen to kitten.
Hemobartonella canis
• Rarely seen in dogs
Cytauxzoon felis
• Fatal disease characterized by anemia
• Thought to be transmitted by ticks
Anaplasma marginale
• Rickettsial organism
• Transmitted mechanically through equipment
Babesia bigemina
• Reportable in cattle
• Texas fever, Redwater fever, Cattle tick fever
Babesia canis
Babesia Gibsoni