Foal Clin Path Flashcards
What is the principle organ of hematopoiesis in utero?
Fetal liver
When does bone marrow contribute to hematopoiesis in utero?
Not until the end of gestation
What adaptations do the equine fetus that facilitate oxygen diffusion across the placenta?
- Lower erythrocyte concentration sof 2,3-diphosphoglycerate— shifts O2 dissociation curve to the left
- Placental countercurrent circulatory pattern
Clinical signs of anemia are what and due to?
— decreased oxygen-carrying capacity of blood
- exercise interolerance, lethargy, weakness, tachycardia, tachypnea
Examples of blood loss that cause anemia in foals
Cesarean section
Fractured ribs: hemothorax, soft tissue hematoma
Bleeding umbilical remnant: external
Trauma: ruptured femoral artery, ruptured gastrocnemeus tendon
Intra-abdominal hemorrhage: ruptured liver or spleen, internal umbilical remnant
Gastrointestinal tract: bleeding gastric ulcers, hemorrhagic enterocolitis, coagulopathy
Thrombocytopenia: alloimmune-mediated, immune-mediated, disseminated intravascular coagulation
Congenital factor deficiency: factor VIII/C, von Willebrand disease
Examples of hemolytic anemia in foals
Neonatal isoertyhrolysis Infection: clostridia spp Disseminated intravascular coagulation Incompatible blood transfusions Autoimmune hemolytic anemia Toxic causes: snake envenomation, rapid dimethylsufloxide administration
Examples of causes of decreased production of rbc as a cause of anemia in foals
Prematurity Anemia of chronic disease Iron deficiency Bone marrow defects associated with maternal administraiton of sulfonamides, pyrimethamine, folic acid Chronic renal disease Fell pony syndrome
Causes for erythrocytosis in foals
Splenic contraction from excitement or handling in addition to dehydration
Hypoxia d/t congenital cardiac dz lead to R to L shunting
(Reported in a hepatic tumor)
Indicators of toxic neutrophils
Dohle bodies
Cytopalsmic vacuolation
Toxic granulation
Basophilic cytoplasm
When are neutrophils functionally mature?
At birth
**phagocytic capacity is limited in foals les than 3 wks of age by opsonic ability of foal’s serum
Phagocytic function of neutrophils is dependent on:
Maturation of serum opsonization factors (ie., complement)
**does not dep on serum IgG
At what degree has lymphopenia should raise suspicion of primary immunodieficiency?
Persistent Lymphopenia < 0.5 x 10^9 cells/L
Severe combined immunodeficiency (SCID) in arabians is inherited through
Autosomal recessive inheritance
SCID foals show decreased function of:
Lymphopenia
Abnormal T & B lymph function test results
**presuckle IgM and other Iggs are not detectable by single radial immunodiffusion (RID) at birth
Fell pony syndrome is associated with:
Decreased major histocompatibility class 2 expression on lymphs and weak T cell response to concanavalin A
Causes of thrombocytopenia in foals
DIC: disseminated intravascular coagulation
Sepsis
Viral infection (EHV-1, equine viral arteritis)
SIRS
Alloimmune thrombocytopenia
Ulcerative dermatitis
Why is alkaline phosphatase (ALP) activity high in foals?
Because of the high osteoblastic activity in growing bone and intestinal development activity & pinocytosis during first 24 hours of life
When does alkaline phosphatase (ALP) decrease and used to assess liver integrity?
After the first month of life
Serum GGT values transiently increase in neonates to what age?
Between 5 and 14 days
<1 hour: 18.9 +/- 7.4
7 days: 48.4 +/- 28.5
1 month 29+/- 9.7
Ammonia levels in neonates in comparison to adults
Young foals have a low ammount of ammonia produce din the colon compared with adults
Hyperammonemia that can cause CNS signs in foals from 6 to 12 weeks of age can be caused by:
Hyperammonemia of Morgan foals
Congenital portosystemic shunts
Ddx for elevated creatine kinase (CK) levels in foals
Perinatal asyphxia Placentitis Trauma at birth Prolonged recumbency Convulsions Glycogen storage disease White muscle disease
What trend does phosphorus follow in the foals?
Similar phosphorus levels at birth, then steadily increase for 2 months
**presumably associated with bone metabolism
Increased creatinine at birth in foals can be caused by:
Fetal stress
Placental pathologic conditions
Renal disease
Blood urea nitrogen concentration increases due to what reason in foals?
Increases with a negative energy balance— when foal’s tissues need to be broken down to provide energy
Differentials for hypoglycemia in foals
Lack of milk intake
Increased metabolic demands: sepsis or SIRS
Reduced gluconeogenesis: HIS, sepsis, premature or in utero stress
Differentials for hyperglycemia in foals
Iatrogenic glucose overload Catecholamine release HIS Prematurity Sepsis SIRS
What is a normal lactate concentration at birth in foals?
3- 5 mmol/L
**progressively decrease in 24 hours
Reasons for increased lactate concentrations in foals?
Tissue hypoxia & poor perfusion
Increased metabolism with sepsis
SIRS induced epinephrine surgers
INC protein catabolism
Muscle activiity (shivering/seizure activity with HIE)
Activaiton of inflammatory cells & mediators
Impaired clearance (hepatic failure)
Characteristics of Agammaglobulinemia in foals
Normal total lymphocyte count— no B lymphocytes
RID: no IgM or IgA, low IgG
Hyperfibrinogenemia in foals less than 2 days of age is an indicator of:
In utero sepsis
Inflammation
Normal CSF values in a foal
< 5 leukocytes/ microL— monocytes & lymphocytes
**no neutrophils present
TP: 1 g/L
Glucose: 80% of blood glucose value
PH: 7.34 to 7.4Increased CSF albumin quotient greater than 2.4 indicates:
INC blood-brain barrier permeability
—> septic meningitis & hypoxic ischemic encephalopathy (HIE)
Uroperitoneum is characterized by peritoneal fluid creatinine to serum creatinine ratio:
Greater than 2
**may also see calcium carbonate crystals on cytology
Synovial fluid concentrations indicative of septic arthritis in foals
> 0.3 x 10^9/L leukocyte count
35 g/L
The urine specific gravity of the first urination after birth should be:
Hyperesthenuric (>1030)
In hydrated foals with normal renal function should have a USG of:
1004 to 1006
Values of usg for isosthenuria
1008 to 1012
Reasons for isosthenuria in foals
Renal dysfunction
HIS or SIRS
Reasons for hypoxemia
Decreased inspired oxygen (fio2) Hypoventilation Difussion impairment Ventilation-perfusion mismatch Right to left vascular shunt (intra & extra-pulmonary shunts)
How to determine if a foal has a right to left shunt?
PaO2 less than 100 mmHg when foal is ventilated on 100% oxygen (intubated and ventilated with FiO2 of 1)
Hypercapnia (PaCO2 >60 mmHg) indicative of hypoventilation associated with hypoxemia may be due to:
Respiratory fatigue: weak resp mm and soft compliant rib cage Altered neuro function (ie., HIE) Other conditions (botulism)
Blood gas samples taken in lateral recumbency have a PaO2 lower/higher than standing?
14 mmHg lower when in lateral than when standing
