Anemia Flashcards
What can account for normal variation in PCV in horses?
Splenocontraction (reserve of up to 30% of the RBC mass).
Breed and age
More athletic animals have a higher resting PCV
How many blood groups are there in the horse?
8
T/F: Aa blood type is the universal donor in the horse
False
There is NO TRUE universal donor in the horse
For all intensive purposes, Aa, Qa, and Ca are considered universal donors
T/F: donkey blood cannot be used for transfusions in horses
True
Due to the donkey factor
The development of clinical signs associated with anemia in the horse is mostly dependent on?
Rate and severity of RBC decrease
What are the clinical signs associated with acute anemia?
Poor performance and exercise intolerance (subtle cases)
Tachycardia, tachypnea, pale MM, lack of episcleral blood vessels Lethargy and depression Systolic murmur Icterus (+/-) Shock, collapse, and death
T/F: regenerative anemias can be assessed by a peripheral blood smear
False
—> horses do not release immature and nucelated RBC
Which value on a CBC might indicate a regenerative anemia in the horse?
RDW (red cell distribution width) —> increased width shows increased size variability and likely younger populations of cells
What causes heinz bodies in horses?
Phenothiazines, onion, red maple leaves
How can you determine rouleaux formation vs aggregation of RBC in the horse?
Diluted blood 1:4 in saline
Rouleaux will disperse
Aggregation will stay aggregated
Hemoglobinemia is associated with what condition?
Intravascular hemolysis
—> pink discolouration to serum
—> hemoglobinuria
What are Howell jolly bodies and what do they indicate in the horse?
RBC with nuclear remnants
1-2% seen in normal horses, therefore not necessarily indicative of increased erythropoiesis
What is the best way to evaluate if an anemia is regenerative in the horse?
Bone marrow
M:E ratio < 0.5
Greater than 5% reticulocytes in the bone marrow
What are the three pathophysiologic mechanisms that lead to an anemia?
Inadequate erythrocytes production
Increased erythrocytes destruction
Blood loss
The most common cause of anemia in large animals is due to what pathophysiologic mechanism?
Decreased RBC production (usually anemia of chronic disease)
A TRUE iron deficiency usually results from what in the horse??
Chronic blood loss
- parasitism
- bleeding GIT lesions
- hemostatic defects
Nutritional deficiency (rare)
A FUNCTIONAL iron deficiency is causes by what?
Pathophysiology of anemia of inflammatory disease
-> alterations in normal iron metabolism and results in depressed marrow production
Normal response to inflammation
Iron sequestered form circulation into storage forms
Mechanism to delay bacteria
Horses with a functional iron deficiency usually dont have a PCV below??
18-19%
TIBC : N to decreased Serum ferritin: N to increased %sat transferrin: N to decreased Serum iron: N to decreased Marrow iron: N to increased
Type of anemia?
Anemia of chronic disease (functional iron deficiency)
TIBC : N to increased Serum ferritin: N to decreased %sat transferrin: N to decreased Serum iron: N to decreased Marrow iron: N to increased
Type of anemia?
Iron deficiency anemia (true - due to blood loss)
How would you treat a True iron deficiency anemia?
Iron supplementation —> iron cacodylate is only safe parenteral prep for the horse
How would you treat a functional iron deficiency?
DO NOT iron supplement
Treat inciting cause/underlying dz
How does anemia result secondary to organ dysfunction ?
Chronic organ disease —> marrow suppression
- decreased erythropoiesis
- toxic compounds (eg endotoxin)
- interference of normal EPO action and production
How does EPO used as performance enhancer result in anemia?
Development of antibodies against human recombinant EPO —> cross reacts with he horses own EPO —> life threatening anemia
(Requires blood transfusions and immunosuppression)
Clinical signs
Anemia with icterus
Pale mucous membranes, tachypnea, and tachycardia
Fatigue, depression, and exercise intolerance
What type of anemia is this due to?
Increased red cell destruction —> extravasular hemolysis
What are the causes of increased red cell destruction?
Oxidative damage -> heinz bodies (maple, onion, phenothiazines, and monensin)
Infectious disease —> EIA, piroplasmosis, clostridial infection, equine erlichiosis
Immune causes—> neonatal isoerythrolysis, IMHA, and incompatible blood transfusion
Piroplasmosis is AKA?
Equine babesiosis —> intraerythrocytic parasitic disease
What are the two causative agents for equine piroplasmosis ?
Theileria equi and Babesia caballi
RBC with pyriform bodies with pointed ends meeting in acute angles
What is the organism?
Babesia caballi
RBC with pyriform bodies dividing into groups of 4, forming the Maltese cross
What organism is this?
Theileria equi
T/F: both T. Equi and B.cabelli are transmitted transstadially (horizontally) within ticks
False
T. Equi = transstadially (horizontally)
B. Cabelli = transovarially (vertically)
What tick sp transmits T. Equi and B.cabelli?
Dermacentor and Rhipicephalus
In endemic areas, what clinical signs do horses usually have with piroplasmosis?
Trick question
In endemic areas, horses are usually infected without clinical signs
Recovered horses are often asymptomatic carriers
How do we diagnose babesiosis infection?
Parasites on blood smear (difficult in carriers or low parasitemeia) —> Giemsa-stain
Serology —> AB detectable in 14days of exposure (IFA or competitive ELISA)
Clinical signs —> hemoglobinuria
Horse with
Fever
Hemolytic anemia
Icterus and hemoglobinuria
Depression, weakness, anorexia, incoordination, lacrimation, mucous nasal discharge, and swelling of eyelids?
DDX?
Piroplasmosis (Babesia)
Equine granulocytic ehrlichiosis (anaplasma)
Equine infectious anemia (lentivirus)
Liver failure with hemolytic anemia
What is the treatment goal of babesiosis in endemic areas?
Treat to alleviate clinical signs
Minimize severity of clinical disease
Presence of organisms required to maintain immunity —- DO NOT clear
What is the treatment goal for babesiosis in non endemic areas?
Complete eradication of organism
Clear and treat serology for reversion to negative status
What drug can be used to eliminate the carrier state of babesiosis?
Imidocarb diproprionate (cholinesterase inhibitor)
This only clears B.cabelli, T.equi is more resistant —> buparviaquone
What are side effects seen with imidocarb? How can this be prevented?
Colic and diarrhea
Can half the dose with 1hr interval between doses
OR
Pretreat with glycopyrrolate > atropine
Equine infectious anemia is AKA?
Swamp fever
What is the causative agent for equine infectious anemia?
Lentivirus of the retrovirus family
- > non-oncogenic retrovirus
- > RNA directed DNA polymerase
- > infects macrophages - integrates into the host genome
What is the main vector for EIA?
Deer and horse fly
Biting insects with interrupted feeding (will go feed on another horse and transmit the virus)
What is the pathophysiology of EIA?
Infects macrophages (cellular and humoral response) -> ag-ab complexes induce hemolysis, vasculitis, and glomerulitis
Anemia
- > immune mediated hemolysis
- > decreased intravascular erythrocytes survival time
- > decreased bone marrow erythrocytes production
Thrombocytopenia
Acute EIA causes an (intravascular/extravascular) hemolytic anemia?
Extravascular
What is the acute form of EIA?
Thrombocytopenia
Fever, depression, and petechial hemorrhage
Anemia not typically seen at this stage
What is the subacute/chronic intermittent form of EIA?
Recurrent episodes of fever, depression, anemia, and icterus (associated with antigenic drift)
Lymphadenopathy, petechial hemorrhage
Edema
Weight loss
What is the chronic imapparent form of EIA?
Chronic “poor doer”
Periodic anemic crisis
What is the only accepted EIA for state and international trade ?
Coggins test
-> can take up to 45days to produce detectable level of antibodies
What test can be used in earlier cases (<45days) to determine EIA infection?
ELISA
What is the treatment for EIA? And regulations for postives cases?
None
REPORTABLE disease
—> cull
If not culled, required permanent quarantine
—> barn with double screening
—> minimum 200yards from closest horse (double fenced pasture)
—> disinfection of all instruments
What can lead to the development of IMHA?
Virus -EIA
Bacterial - clostridum
Protozoa- equine ehrlichiosis/babesiosis
Neoplasia - lymphosarcoma
Drugs- penicillin, suphas, phenylbutazone
Immune mediated dz- purpura hemorrhagica or SLE
