Hemolymphatic System Flashcards
What horses have the highest PCV?
athletic horses that need increased oxygen delivery to muscle and vital organs
- Thoroughbred
- Standardbred
- American Quarterhorse
- Arabian
- Percheron
What is mean corpuscular volume? What are 2 causes of an increase? Decrease?
RBC size - (PCV x 10)/RBC
- INCREASED: regenerative anemia, older horses
- DECREASED: iron deficiency anemia
What is mean corpuscular hemoglobin (concentration)? What can cause an increase and decrease?
measurement of the average amount of hemoglobin in each red blood cell
- INCREASED: intravascular hemolysus
- DECREASED: iron deficiency anemia
What are 3 unique components of equine RBCs on a blood smear?
- Rouleaux formation
- Howell-Jolly bodies - DNA-containing inclusions found after erythrocyte maturation
- Heinz bodies
What are the 3 most pathogenic equine blood types?
- Aa
- Ca
- Qa
What do the group systems and antigenic factors of equine blood types indicate?
specific gene encoding for the RBC surface antigen
different alleles within each blood group that encode for antigen factors
What is the direct Coombs test?
detects the presence of antibodies against red blood cells by washing patient’s RBC with an anti-immunoglobulin antibody (Coombs reagent)
- diagnoses immune-mediated hemolytic anemia
What is an indirect Coombs test?
detects the presence of antibodies against red blood cells by incubating recipient serum with normal RBCs of known antigenicity (compatible blood group) and monitoring for gross agglutination - equine polyvalent Coombs reagent is then used to enhance detection of any reactivity
What is required to evaluate regenerative or non-regenerative anemia?
bone marrow aspirate from the sternum
Erythrocytosis:
What are 3 causes of relative erythrocytosis in horses?
high concentration of red blood cells due to low amounts of plasma in relation to the number of red blood cells
- dehydration (hemoconcentration)
- endotoxemia (hemoconcentration)
- splenic contraction (excitement/stress)
What is primary erythrocytosis?
polycythemia vera - myeloproliferative disease resulting from the autonomous clonal expansion of hematopoietic progenitor cells
- normal PaO2 and normal/decreased EPO
What is secondary appropriate erythrocytosis? 3 causes?
increased RBC due to compensatory response of EPO production in cases of hypoxia
- chronic pulmonary disease
- right-to-left cardiovascular shunting
- high altitude
What is secondary inappropriate erythrocytosis? 2 causes?
increased RBC due to increased EPO secretion without the presence of hypoxia
- EPO-secreting neoplasms
- renal pathology causing local hypoxia
What are the 2 most common causes of anemia?
- blood loss - trauma, sx, ecto/endoparasites, GI bleeds, immune-mediated thrombocytopenia
- hemolysis - neonatal isoerythrolysis, red maple leaf toxicosis, EIA
(+ non-regenerative - inflammatory disease, chronic abscessation, chronic pneumonia/pleuritis, lymphoma)
What is indicative of anemia? How does this affect TP and bilirubin? How is anemia characterized?
decreased PCV and HCT
- low TP indicative of blood loss
- high bilirubin indicative of hemolysis
erythropoietic failure - BM aspiration, biopsy, serum iron and TIBC, renal function, EPO, serum copper. B12, and folate, GI absorption, chronic inflammation
What blood cell is not present in the horse?
reticulocytes - RBCs mature in the BM, upon regeneration there will be larger RBCs observed (macrocytes)
What are common causes of external and internal blood loss in horses?
EXTERNAL = wound, trauma
INTERNAL = GI/respiratory/GU hemorrhage, EIPH, guttural pouch mycosis, ruptures uterine artery
How is blood loss diagnosed? Internal specifically?
clinical signs and lab tests, like coagulation testing and platelet counts
- ultrasound
- rectal palpation
- thoracocentesis
- abdominocentesis
What is the normal blood volume in horses?
8% of BW
500 kg horse —> 0.08 x 500 = 40 L
How does attitude, HR, and BP change with blood loss?
- < 15% = normal, 30-40, normal
- 15-30% = anxiety, 40-60, normal
- 30-40% = anxiety or depression, 60-80, decreased
- > 40% = obtundation, > 80, very decreased
What are the 3 steps to blood loss treatment?
- stop bleeding - easy if external with compression, clamps, and tourniquets
- treat hypovolemic shock
- blood transfusion
How is hypovolemic shock treated in horses with blood loss?
- crystalloids (20 mL/kg bolus)
- hypertonic 7.2% NaCl (2-4 mL/kg)
In what 2 ways is the necessity for a blood transfusion determined?
- PCV - <20% acute blood loss or <12% over 24 hours
- lactate - leukocytes within closed body cavities consume glucose and produce lactate
What 4 additional treatments may be necessary in horses with blood loss?
- aminocaproic acid
- Yunnan Baiyao
- oxygen
- naloxone
What is required for donors in blood transfusions?
blood typed and tested negative for Aa and Qa antibodies and antigens
- BEST = large, quiet STB or AQH gelding with no exposure to blood products and is UTD on vaccines and Coggins tests