LARGE ANIMAL HEMATOLOGY

7 LARGE ANIMAL HEMATOLOGY



Shannon Jones Hostetter, Claire B. Andreasen



1 Can reticulocyte counts be used as a measure of a regenerative response in anemia in the horse? Why or why not?


Reticulocyte counts are not used to evaluate the bone marrow response in equine anemia. Reticulocytes are not found in significant numbers in the peripheral blood of the horse in health or disease because they mature within the bone marrow.



2 How do you determine a regenerative response in equine anemias?


Because horses do not release reticulocytes from the bone marrow into circulation in significant numbers, reticulocyte counts cannot be used as an index of regeneration in this species.


Methods to evaluate bone marrow responses in horses include repeated hematocrits, bone marrow evaluation, and red cell distribution width (RDW).



3 Ingestion of bracken fern by ruminants has been associated with what hematologic abnormality?


Bracken fern toxicosis in ruminants can result in aplastic anemia.



4 What is the average erythrocyte life span in the horse, cow, sheep, and pig?


The average erythrocyte life span in the horse is 145 days versus 160 days in the cow and 150 days in sheep. Pig erythrocytes have a substantially shorter life span that averages approximately 86 days.



5 Which vitamin deficiency can cause a nonregenerative anemia in swine?


Vitamin E deficiency in swine can produce a nonregenerative anemia characterized by erythroid hyperplasia and dyserythropoiesis in the bone marrow.



6 Erythrocytes from healthy Angora goats have what characteristic shape?


Angora goats normally have elongate erythrocytes known as fusocytes.



7 What group of domestic mammals normally has oval erythrocytes?


Camelids, including llamas and alpacas, have oval erythrocytes often referred to as elliptocytes.



8 Identify several morphologic features of normal bovine erythrocytes.


Bovine erythrocytes average approximately 5.5 microns (μ) in diameter and have slight central pallor. Anisocytosis and crenation are common morphologic variations in erythrocytes of healthy bovines.



9 What are the differences in erythrocyte size in ruminants?


Sheep erythrocytes (3.2-6.0 μ) and goat erythrocytes (2.5-3.9 μ) are smaller than cattle erythrocytes (4-8 μ). This can cause difficulties in obtaining accurate erythrocyte counts with cell counters. The thresholds must be adjusted for the smaller erythrocyte size.



10 What are the characteristic hematologic changes resulting from ingestion of red maple (Acer rubrum) leaves in the horse, and what is the pathogenesis of these changes?


Red maple toxicity in the horse causes oxidative injury to erythrocytes, leading to intravascular hemolysis. The characteristic hematologic changes include anemia, Heinz body and eccentrocyte formation, methemoglobinemia, and hemoglobinemia.



11 When do cattle have circulating reticulocytes?


In health, cattle do not release reticulocytes from the bone marrow in significant numbers; normal erythrocyte maturation occurs in the bone marrow. Low numbers of circulating reticulocytes (approximately 1% or greater) are associated with a regenerative response to anemia.

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Aug 26, 2016 | Posted by in INTERNAL MEDICINE | Comments Off on LARGE ANIMAL HEMATOLOGY

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