Hemolymphatic System, Pt. 2 Flashcards
What 3 conditions are associated with neonatal isoerythrocytosis? What does this result in?
- foals inherit RBC type (Ag) from sire
- Aa- or Qa- mares become sensitized to Ag and produce antibodies due to exposure from previous pregnancies, blood transfusions, or transplacental contamination
- colostrum with antigens are ingested and absorbed by the foal
destruction of foal RBCs by maternal Ab
In what horses is there a higher incidence of neonatal isoerythrocytosis? What blood groups are strongly antigenic?
10% in mules (1% in TB, 2% in STB)
- Aa
- Qa
- donkey factor
- occasionally Ua, Pa, Qc, and Db
What can possibly prevent neonatal isoerythrocytosis?
Ca —> antibody-mediated immunosuppression
When does neonatal isoerythrocytosis occur? What clinical signs are seen?
foal is born healthy but develops signs 24-36 hours (or several days if mild)
- progressive lethargy and weakness
- pale to yellow MM
- tachycardia, tachypnea
- discolored urine
- seizure, death
What 2 laboratory results are seen in foals with neonatal isoerythrocytosis?
- hemolytic anemia: decreased PCV, RBC, and Hb
- increased bilirubin, hemoglobinemia, hemoglobinuria
How can immune reactions be confirmed in cases of neonatal isoerythrocytosis?
- INDIRECT COOMBS: test mare serum or colostrum for antibodies
- DIRECT COOMBS: presence of antibodies attached to foal RBC
What test is done on foals to confirm neonatal erythrocytosis?
jaundice foal agglutination test —> foal RBC exposed to mare colostrum or serum, detecting agglutination and NOT hemolysis
What treatment is recommended in foals within or after 24 hours of developing neonatal isoerythrocytosis?
< 24 hours = withhold milk (muzzle, strip mare) and offer alternative sources
> 24 hours = decrease stress, give fluids and antibodies, and offer a blood transfusion of washed mare RBCs or compatible donors
What 4 complications are associated with neonatal isoerythrocytosis treatment with blood transfusions?
- hyperbilirubinemia - kernicterus (exchange transfusions)
- iron toxicity
- sepsis
- liver failure
In what 3 ways can neonatal isoerythrocytosis be prevented in the mare?
identify risk —> Aa, Qa, previous NI foal
- screen serum 2 weeks before the due date and repeat every 2 weeks
- check colostrum for reactivity
- Domperidone before foaling
In what 2 ways can neonatal isoerythrocytosis be prevented in the foal?
provide alternative sources of colostrum
- withhold milk with a muzzle or strip the mare
- provide frozen colostrum for NI- mare or milk from goats, NI- mare, or Mares Match
How is the jaundiced foal agglutination test performed?
- collect colostrum from mare
- collect EDTA tube from foal before nursing
- set up 6 tubes and add 1 mL of saline and perform serial dilutions
- add 1 drop of foal blood to each tubes and mix
- centrifuge tubes for 2-3 mins
- invert each tube and pour liquid out to observe clumping
- if positive at 1:8 dilution, don’t let foal nurse
Neonatal isoerythrocytosis:
What are the main colostrum and foal causes of failure of passive transfer of maternal antibodies? What risk is associated?
COLOSTRUM - none produced, poor quality or quantity
FOAL - cannot get up, suckle, or absorb
sepsis!
How is failure of passive transfer diagnosed?
SNAP foal IgG test using foal’s blood
- < 400 mg/dL IgG = complete failure (spot lighter than both references
- 400-800 mg/gL IgG = partial failure (intermediate spot color)
- > 800 mg/dL IgG = proper nursing (spot darker than both references)
How is failure of passive transfer prevented?
early recognition is key - often too late by time of diagnosis
- educate owner/manager: monitor foal, assist with colostrum administration, clean environment
- evaluate pre-suckle colostrum, should be sticky, yellow, and thick and > 1.060 SG
At less than 12 hours post-partum, what treatment is recommended for foals with failure of passive transfer?
1-2 L of good-quality equine colostrum from a bank of healthy, blood typed, and vaccinated mares (200-250 mL can be collected)
At over 12 hours post-partum, what treatment is recommended for foals with failure of passive transfer?
at this point colostrum cannot be absorbed, commercial plasma that is from vaccinated mares with known IgG concentrations and negative for Aa and Qa alloantigens
What should be done if there is no blood typing available for foals treated with plasma in failure of passive transfer?
can use plasma from untransfused geldings that are fully vaccinated and negative for Aa and Qa
What adverse reactions are associated with plasma transfusions in foals with failure of passive transfer?
- muscle fasciculations
- increased HR, RR, and T
- distress
- abdominal pain
- pale MM
- collapse