Failure of Passive Transfer

What is Failure of Passive Transfer (F.P.T.)?

Foals are born without protective immunity against infectious disease organisms. All foals require “passive transfer” of infection-fighting proteins called antibodies that are found in the mare’s first milk, or colostrum. If a foal does not obtain enough quality colostrum, they will not be protected from viruses and bacteria. This is referred to as failure of passive transfer (F.P.T.) of immunity. Approximately 5-20% of newborn foals are diagnosed with F.P.T. and are at risk for developing serious medical conditions.

Antibodies transfer from the mare to the foal in the first 12 hours after birth. During this period the foal must consume at least two litres of good quality colostrum. 85% of antibodies are absorbed in the first 6-8 hours.

How do I know my foal has received enough antibodies?

Have your vet examine the foal and test the immunoglobulin (IgG, an antibody type) concentrations at eight to twelve hours after birth to assess passive transfer status.

If the foal has partial or complete F.P.T., antibodies must be administered via fresh or frozen oral colostrum within the first 12-18 hours of life, commercial products, or intravenous plasma (if 24 hours have passed).

Blood test to measure foals antibody level
IgG Levels	Significance
< 200 mg/dL of plasma antibodies	Complete FPT
200 – 800 mg/ dL	Partial FPT
> 800 mg/ dL	Successful passive transfer

How do I prevent F.P.T.?

• Vaccinate the mare four to six weeks before foaling to ensure she develops antibodies to deliver via the colostrum
• Monitor for common causes, such as early lactation (monitor udder regularly), placental infections (monitor regularly for vulval discharge), premature birth, unable to stand and suckle, and poor quality colostrum.
• Ensure the foal stands and nurses
• Check the IgG status of the colostrum using a refractometer and/ or check the IgG status of the foal within 12 hours of birth
• Supplement colostrum or plasma as needed.

AT BIRTH:

Verify the foal:                

• Stands within one hour of birth               
• Nurses within two hours of birth            

REMEMBER: not all foals with F.P.T. develop life-threatening infections, and not all foals achieving passive transfer of immunity are guaranteed to be healthy. Work with your vet to prepare for foaling and ensure the newborn foal receives good quality colostrum.