E2: Anemia Flashcards
Anemia is defined as a reduction in ____ and/or the amount of ______.
RBC number
hemoglobin
The spleen has a reserve of up to ___% of the red cell mass.
30
What drug class can cause red cell sequestration and a reduced PCV? Why/how?
Promazine tranquilizers
Splenic relaxation
Hot-blooded horses, such as TBs, typically have a ______(higher/lower) PCV than cold-blooded horses, such as Drafts.
Higher
(35-53% vs 24-44%)
How many blood group systems do horses have? Which one is the universal donor?
8
There is no universal donor in horses
Why should donkey blood not be used for horse transfusions?
Donkey factor makes donkey blood incompatible with horses
T/F: Clinical signs associated with chronic anemia are less severe than those for acute anemia.
False, acute more severe
T/F: It is not possible to assess RBC regeneration on a peripheral blood smear of the horse.
True
Which is normal in horses, agglutination or rouleaux?
Rouleaux
What is the best way to evaluate response to anemia in horses? What type of tube do you put your sample in?
Bone marrow aspiration
LTT/EDTA (purple top)
What is the most common cause of anemia in large animals?
Chronic Disease
Splenic contraction can increase measured PCV by up to ___%. The PCV in the spleen is usually around ___%.
50
80
Why are MCV and MCH not very helpful when evaluating anemia in horses?
Macrocytosis and polychromasia do not occur in horses
What is shown in this picture (overall and black arrowhead)?
Rouleaux
Howel Jolly Bodies (arrowhead)
What is a normal RDW in a horse? What can this measurement allow you to infer?
19
Regeneration if RDW > 19
What is the normal range for PCV (generally) for horses?
29-53%
In horses, what is typically the cause of iron deficiency?
Chronic blood loss (parasites, bleeding, hemostatic defects)
Horses with functional iron deficiency anemia typically have PCV less than ______%.
18-19
Where is most of the total reserves of iron in a horse? Where else is it stored?
Ciruclating RBCs (2/3 of total)
Liver, Spleen, Bone marrow
What is the carrier protein responsible for iron transport and distribution in the body? How can it be measured?
Transferrin
Measured by evaluating TIBC (total iron binding capacity)
What is the only safe parenteral preparation for iron supplementation in the horse?
Iron cacodylate
T/F: PCV varies with breed and age.
True
What patholgy and drug can cause agglutination in horses?
IMHA
Heparin
How can you evaluate regeneration in a horse, aside from interpreting RDW? What indicates regeneration?
Bone marrow aspirate for Myeloid-Erythroid Ratio
M:E < 0.5 = regeneration
>5% reticulocutes in bone marrow= regeneration
What factors affect the CS and their severity in an anemic horse?
Severity of anemia
Duration
Rapidity of anemia (if slowly progressive body can compensate)
What 3 basic pathophysiologic processes cause anemia?
Inadequate production
Increased destruction
Blood loss
What findings do you expect in a horse with anemia of chronic disease?
Concurrent disease
Increased fibrinogen (severity and chronicity)
Increased WBCs
PCV >18-19%
How is fibrinogen usually measured in horses? When does it increase due to inflammation?
Indirectly (heat precipitation)
>48 hours
What value indicates iron binding capacity?
TIBC
In horses with anemia of chronic disease (i.e. functional iron deficiency), the available iron pool (TIBC, serum iron) are _______ while iron storage (serum ferritin, marrow iron stores) are _______.
In horses with a true iron deficiency the opposite occurs.
Decreased or Increased?
(normal to) Decreased
(normal to) Increased
How can you treat anemia caused by EPO administration?
Corticoteroids +/- Transfusion
However, may not be treatable and thus fatal
What causes increased red cell destruciton in horses?
Most important: Infectious diseases
Immunologic causes
Toxins (e.g. wilted Red maple leaves)
In areas where babesiosis or piroplasmosis are endemic, why would you be concerned if an older horse develops fever, icterus and anemia following a stressful event?
May have been a carrier of these diseases and not shown CS until a stressor caused it to emerge
What is the more severe form of babesiosis caused by? What does it cause that the less severe form does not? What does this cause?
Babesia equi
Causes intravascular hemolysis (as well as extravascular, which is caused by both this and B. cabali)
Hemoglobinemia and hemoglobinuria (with B. equi but not B. cabali)
What is the preferred/most commonly used test for babesiosis? Why is it better than analyzing a blood smear?
Compliment Fixation Test (CFT)
It can identify carriers
Do you expect to see parasites on a blood smear if a horse is presenting with clinical signs of babesiosis? What clinical signs are these?
Yes
Fever, Tachycardia, Tachypnea, Weakness
Why does the treatment goal for babesiosis vary depending on whether it is endemic in that area or not?
In endemic areas, you do not want to clear the organism completely because maintaining a low level confers a certain level of immunity against the disease. So the goal is to minimize the severity of the disease and clinical symptoms.
In non-endemic areas the goal is to become seronegative for the disease
What is the treatment protocol for Babesiosis?
Imidocarb dipropionate (cholinesterase inhibitor)
Prevent diarrhea/colic by spacing out the dose (give 1/2 now and the rest 1 hour later) or by pre-treating with glycopyrrolate (or atropine, but it can cause GI issues)
+/- Buparvaquone for acute B. equi
What is “Swamp Fever”?
Equine Infectious Anemia
What vectors are associated with EIA?
Deer and Horse flies
+/- mosquitoes
How can EIA be transmitted iatrogenically?
Most common: Dental equiptment
Needles, NG tubes, gloves
What type of virus is EIA?
Retrovirus- Lentivirus
What cells does EIA affect? How does it cause anemia?
Macrophages
Immunological pathophysiology: Antigen-Antibody complex deposition -> INDIRECT destruction of RBCs -> Immune-mediated EXTRAVASCULAR hemolysis
What causes the recurrent episodic hemolytic crises in horses with EIA?
Antigenic drift/shift (Mutation) occuring in a sequential predetermined pattern
What is the recommended and USDA-accepted test for EIA? What can you use to verify this test?
Coggins Test
ELISA test
How long does it take for a horse post-EIA infection for a positive AGID test result? Which test can be used for earlier cases?
(Coggins is an AGID test)
45 days
ELISA
What are the general requirements for isolation/quarantine?
Double screening insect control in barns
Minimum of 200 yards away from closest horse, separated by double fencing pasture (due to vector behavior)
Disinfection of all instruments used on affected horses
If leave facility, must be marked with “A” on neck or shoulder
What is one example of each of the common secondary causes of IMHA: Viurs, Bacteria, Neoplasia, Drugs, Immune-Mediated disease?
Virus: EIA
Bacteria: Clostridium perfingens
Protozoa: Ehrlichia, Babesia
Neoplasia: LSA
Drugs: Penicillin, Sulfas, Phenylbutazone
Immune-mediated: Purpura hemorrhagica, SLE
What can trigger an antibody response leading to IMHA?
Alteration of the RBC membrane (direct or indirect damage)
Alertations in the immune system
Alterations in the immune system stimulation
What causes Equine Granulocytic Ehrlichoisis? What cells are infected?
Anaplasia phagocytophilia
Neutrophils and Eosinophils
What are the compensatory mechanisms when hemorrhage occurs?
Cardiac (first mechanism)- heart rate
Vascular: vasoconstriction, plasma volume increase - autotransfusion (fluid absorption from 3rd space, increase in glucose (fluid shift))
Hormonal: Vasopressin/ADH release
Why is it difficult to evaluate the extent of hemorrhage in horses?
Splenocontraction
When will a horse bottom out due to hemorrhage?
2 days
What are the criteria used to determine the need for a blood transfusion?
Absolute PCV number
+
Severity of loss: rapidity of decreasing PCV
+
Time: Acute vs Chronic
+
Clinical signs
+
Determining the problem: Volume/perfusion or O2 carrying capacity
How long do RBCs from a transfusion last?
2-4 days
When can you use crystalloids to replace blood lost through hemorrhage?
If the problem is VOLUME not O2 carrying capacity
When the blood volume loss is 15-30%
When can you use colloids to replace blood lost through hemorrhage?
Blood loss >25% causing a concern for RETAINING the fluids in the vasculature due to LOW PROTEIN
Can give Plasma +/- Hetastarch (Hetastarch is more cost-effective)
When can you use a blood transfusion to replace blood lost through hemorrhage?
Blood loss >50%
PCV <10-12% (especially if acute)
For O2 carrying capacity issues
