Equine Anemia Evaluation & Management Flashcards

1
Q

what is the difference in the lifespan between equine and canine erythrocyte

A

equine cells have a longer lifespan

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2
Q

why is it difficult to determine if anemia is regenerative in horses

A

because immature red cells are not released from bone marrow to circulation

no reticulocytes in regenerative anemia

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3
Q

what is the average lifespan of red cells

A

140-150 days

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4
Q

what red cell parameters can help determine if there is regeneration

A

the MCV and MCHC

in regeneration it is likely that the cells will be larger

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5
Q

what type of tube should you use for an accurate platelet count

A

citrate tubes

they clump (rouleaux) in EDTA tubes causing the count to be lower than it is

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6
Q

when do band neutrophils occur

A

when there is an acute inflammatory problem

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7
Q

at what platelet value should you be concerned

A

below 50

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8
Q

what are more sensitive parameters to determine if there is inflammation present besides the white cell parameters

A

acute phase proteins are more sensitive

because horses can have a number of infectious conditions but the white cell count can be normal

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9
Q

what is a normal PCV in throughobreds

A

~38-45%

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10
Q

what is a normal PCV in standardbreds

A

~38-40%

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11
Q

what is a normal PCV in warmbloods

A

~33-35%

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12
Q

what is a normal PCV in clydesdales

A

~30-33%

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13
Q

what is a normal PCV in mixed cold blood

A

~33%

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14
Q

what effect does spenic contraction have on the PCV

A

30% of red cell mass

will increase PCV in exercise/fear

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15
Q

what causes splenic relaxation and what effect does this have on the PCV

A

sedation

lowers PCV to low 20s even

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16
Q

what evironmental factors can have significant effects on the hemotology values

A

exercise

feeding

travel

stress

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17
Q

what are the general clinical signs of anemia in horses due to acute blood loss/hemolysis (3)

A
  1. tachycardia
  2. tachypnea & hyperpnea (indicative of hypovolemia and hypoxemia)
  3. mucous membrane colour depends on severity of loss
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18
Q

what are the general clinical signs of anemia in horses due to chronic blood loss/hemolysis (5)

A
  1. exercise intolerance
  2. weight loss
  3. pallor of mucous membranes only clinically evident at <20-24 l/l
  4. adaptive tachycardia at <20 l/l
  5. hemic murmur due to decreased viscosity, increased turbulence
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19
Q

at what PO2 would you start seeing cyanosis

A

60 mmHg

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20
Q

what are the features of regeneration on blood smears and hematology (3)

A
  1. howell jolly bodies
  2. increase in MCV
  3. anisocytosis more marked
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21
Q

what is the arrow showing

A

howell jolly body

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22
Q

at what rate does regeneration typically occur

A

increase of 0.32-0.42% per day (ie ~3 days to increase by 1%)

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23
Q

how long does it take for albumin to recover during regenerative anemia

A

5-10 days

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24
Q

how long does it take globulins to recover in regenerative anemia

A

3-4 weeks

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25
Q

what is the best sampling site to assess if anemia is regenerative

A

facial venous plexus

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26
Q

what can occur that you shouldn’t confuse for agglutination

A

strong red cell rouleaux formation

add adequate drops of saline

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27
Q

how do you test for genuine autoagglutination

A

in saline agglutination test 1 drop blood + 3 drops saline –> vigorous swirl

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28
Q

what are the tests for IMHA

A

in saline agglutination test

coombs test

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29
Q

what are infectious diseases that can cause anemia

A

equine infectious anemia

equine piroplasmosis

equine ehrlichiosis

equine trypanosomosis

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30
Q

how is bone marrow evaluated

A

collected from equine sternum with jamshidi needle

local anesthesia and stab incision

multiple smears made immediately

fragments of marrow used to make impression smears

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31
Q

what is the myeloid:erythroid ratio

A

normal ratio should be 0.5-2.4

if less than 0.5 M:E ratio with >5% reticulocytes indicates adequate regenerative response to anemia

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32
Q

what can a bone marrow evaluation test

A

nonresponsive vs responsive anemias (most IMHA cases are regenerative unless precursor cells targeted)

myeloproliferative disorders

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33
Q

what are the 3 categories of causes of equine anemia

A
  1. acute/chronic erythrocyte loss
  2. increased erythrocyte breakdown
  3. decreased red cell production
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34
Q

what are the reasons for acute/chronic erythrocyte loss

A

internal (hemorrhage into chest, abdomen, gut, bladder)/external hemorrhage

decreased survival in anemia of chronic disease

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35
Q

what are the types of erythrocyte breakdown

A

intra-/extra-vascular hemolysis

primary vs secondary

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36
Q

what are the 5 areas where acute blood loss can occur

A
  1. trauma or surgery: intra-abdominal, intrathoracic, arterial laceration
  2. respiratory: epistaxis, exercise induced, pulmonary artery rupture
  3. GIT: mesenteric tear, strongylus vulgaris arteritis
  4. urinary: renal hemorrhage
  5. uterine artery rupture: foaling complications
37
Q

what is the approx circulating blood volume in horses

A

80-100 ml/kg

38
Q

how much blood can a horse loose prior to collapse

A

20-30%

8-12 L for 500kg horse

39
Q

what are the clinical signs for acute hemorrhage that might indicate a transfusion is needed

A
  1. marked tachycardia
  2. variable pallor to mucous membranes
  3. preliminary signs of tachypnea & hyperpnea (hypoxia/hypercapnia)
40
Q

what are the GIT causes that can cause chronic blood loss

A
  1. gastric ulceration (particularly of glandular mucosa)
  2. severe colitis
  3. strongylus vulgaris arteritis
41
Q

what are the respiratory causes that can cause chronic blood loss

A
  1. exercise induced pulmonary hemorrhage
  2. epistaxis (ethmoidal hematoma)
42
Q

what urinary causes can lead to chronic blood loss

A
  1. renal hemorrhage
  2. bladder hemorrhage
43
Q

what coagulopathies can cause chronic blood loss

A
  1. thrombocytopenia
  2. factor VIII deficiency (heritable x-linked hemophilia, prolonged PTT, normal PT)
44
Q

how would you investigate the GIT if you suspect chronic blood loss from here

A
  1. gastroscopic exam
  2. fecal egg count
  3. fecal occult blood
45
Q

how would you investigate the resp system if you suspect chronic blood loss from here

A
  1. endoscopy
  2. cytology
46
Q

how would you test the urinary system if you suspect chronic blood loss from here

A

urine sediment cytology

47
Q

how do you assess coagulopathies

A
  1. acurate platelet count
  2. measure PT and PTT times
  3. assess hepatic funcitons
  4. assay factor VIII concentration
48
Q

how do you assess if chronic hemorrhage/loss has stopped

A

check PCV and total serum protein levels

49
Q

if the PCV and TSP remain low has the chronic hemorrhage/loss stopped

A

no

50
Q

if the PCV is stable and TSP has increased has the chronic hemorrhage/loss stopped

A

yes but no regeneration

51
Q

if the PCV has increased and TSP has increased has the chronic hemorrhage/loss stopped

A

yes and regeneration

the cells might be larger than expected and howell jolly bodies will be present

should increase by a point over 3 days or so

52
Q

what are the types of IMHA

A

primary and secondary

53
Q

what is primary IMHA

A

antibodies against erythrocytes

54
Q

what is secondary IMHA

A

immune complexes (external antigens) are attached to the erythrocytes

disease alters the RBC membrane

multiple causes

55
Q

what are the causes of secondary IMHA

A
  1. respiratory tract infections
  2. streptococcal abscesses
  3. drug induced
  4. neoplasia
56
Q

how can respiratory tract infections cause secondary IMHA

A

viruses such as EIV

deposition of antigen on erythrocyte membrane

affected cells removed by reticulo-endothelial system and continues until all affected cells are removed

subsequent regeneration

57
Q

what drugs can cause secondary IMHA

A
  1. penicillins & sulphonamide antibiotics
  2. phenothiazine tranquilizers (acepromazine)
58
Q

what neoplasia can lead to secondary IMHA

A
  1. lymphoma
  2. fibrosarcoma
59
Q

how is IMHA treated

A
  1. identify and discontinue suspected medications
  2. dexamethasone if severe hemolysis
  3. blood transfusion if clinical evidence of requirement
60
Q

what steroids can be used to treat IMHA

A

0.1 mg/kg IV dexamethasone daily, decreasing to 48h

then change to prednisolone 1 mg/kg SID if longer term treatment

61
Q

what is neonatal isoerythrolysis

A

a foal is born to a mare and stallion where the stallion has a different blood group to the mare

if the mare is negative for AA and Qa but the foal is positive on AA and Qa –> the mare might produce antibodies which can damage the foals red cells

62
Q

when does neonatal isoerythrolysis occur usually

A

most often in multiparous mares

63
Q

what are the clinical signs of neonatal isoerythrolysis

A

anemia

icterus

weakness

increased RR, HR

pale mm’s

64
Q

what is the onset of neonatal isoerythrolysis

A

onset/severity variable

but usually 2-3 days

65
Q

how do the mares antibodies destroy the foals red cells in neonatal isoerythrolysis

A

through the colosutrm

66
Q

how is neonatal isoerythrolysis diagnosed

A
  1. signs, hematology
  2. rule out DDx
  3. immunological testing
  4. foal RBCs + mare serum/colostrum to see if there is lysis
67
Q

how is neonatal isoerythrolysis treated

A
  1. supportive care (stall rest, nutrition)
  2. blood transfusion
  3. suitable colostrum donor
68
Q

how is neonatal isoerythrolysis prevented

A
  1. check compatibility of pairing particularly if mare is Aa/Qa negative (blood typing)

2. Aa/Qa negative stallions less likely to cause NIE in foals

  1. prevent nursing for 24 h (alternative source of colostrum)
69
Q

what are the causes of non regenerative anemia in horses (7)

A
  1. iron deficiency
  2. chronic disease (infection/inflammation)
  3. bone marrow failure
  4. coagulopathies
  5. admin of human EPO
  6. chronic hepatic disease
  7. chronic renal disease
70
Q

what bone marrow diseases can cause non regenerative anemia

A
  1. myelophthisis
  2. myeloproliferative disorder
  3. bone marrow toxins: PBZ, chloramphenicol
71
Q

what can cause iron deficiency

A
  1. chronic hemorrhage
  2. nutritional deficiency (rare)
72
Q

what would a non-regenerative anemia work up look like

A
  1. search for hemorrhage
  2. coagulation profile
  3. assess metabolic function
  4. is there iron deficiency?
73
Q

how would you search for a hemorrhage if you suspect non regenerative anemia (6)

A
  1. gastroscopic exam
  2. fecal egg count
  3. fecal occult blood
  4. endoscopy + cytology
  5. thorax and abdominal US exam
  6. urine sediment cytology
74
Q

what is a coagulation profile

A
  1. assess accurate platelet count
  2. measure PT and PTT times
  3. citrate blood tubes
  4. assay factor VIII concentration
75
Q

how would you assess metabolic function to tell if non regenerative anemia (4)

A
  1. assess hepatic function
  2. measure renal failure
  3. is there an inflammatory response
  4. are acute phase proteins increased
76
Q

how do you determine if there is an iron deficiency (4)

A
  1. low serum ferritin concentraion
  2. decreased % saturation of plasma transferrin
  3. increased total iron binding capacity (TIBC)
  4. increase of hypochromic erythrocytes
77
Q

what is the most likely cause of iron deficiency

A

external blood loss

78
Q

how do chronic diseases cause anemia

A
  1. shortened erythrocyte lifespan
  2. decreased release of iron
  3. decreased bone marrow response to EPO
79
Q

what chronic diseases can cause anemia

A
  1. pleuropneumonia
  2. internal abscessation
  3. peritonitis
  4. chronic parasitism
  5. neoplasia
80
Q

what are the causes of inadequate erythropoiesis

A
  1. nutritional deficiencies
  2. myelophthisic anemia
  3. bone marrow aplasia
81
Q

what nutritional deficiencies can cause inadequate erythropoiesis

A
  1. prolonged administration of sulphonamides
  2. decreased folate and vit B12 production by GIT flora
82
Q

how does bone marrow aplasia cause inadequate erythropoiesis

A

neoplastic infiltrate in bone marrow

83
Q

if there is true neoplasitc problems with red cell precursors what will likely be seen

A

other cell lines will likely be affected

84
Q

what will you likely see in bone marrow aplasia

A

likely to have pancytopenia with decreased neutrophils & decreased platelets if myeloid stem cell involved

85
Q

what is the least common cause of non regenerative anemia

A

bone marrow aplasia

86
Q

what are laboratory signs of acute blood loss

A
  1. low PCV
  2. low Hb
  3. low TSP
87
Q

what are the labortory signs of hemolysis (5)

A
  1. low PCV
  2. normal TSP
  3. increase in unconjugated bilirubin
  4. increase MCH
  5. increased hemoglobinuria
88
Q

what are the laboratory signs of chronic disease (5)

A
  1. low PCV
  2. low Hb
  3. relatively high TSP
  4. may be inflammatory leukogram with increased APPs
  5. may be reduced ferritin and high TIBC