Horse Side Vet Guide ®

Equine Health Resource

Foal or Newborn, Antibody Testing, IgG Test



Foals obtain their first, critical antibodies from their dam’s first milk (colostrum). Failure to ingest and absorb these antibodies results in the so called “failure of passive transfer”, a potentially lethal condition if not promptly remedied.

Veterinarians routinely test newborn foals for adequate antibody levels using a blood test.

Blood is usually taken from foals at the post-foaling exam. It may take 6-8 hours after nursing before the antibodies rise to their maximal level. We usually perform this test at 12-24 hours after foaling. Testing of neonatal foals for antibody is considered good standard of practice and likely reduces risk for failure of passive transfer.

There are several different “stall-side” test kits that are available for this test.

Reasons to UseRelated Observations

Foal or Newborn, Milk Drying on Face
Foals, Twins Born Alive
Newborn Foal, Seems Disoriented or Dazed
Foal or Newborn, Heart Rate Elevated
Newborn Foal, Fails to Stand or Nurse
Foal or Newborn, Abdominal Pain (Colic)
Newborn Foal, Gums (Mucous Membranes) Abnormal Color
Foaling, Red Sac Shown, Red Bag Delivery
Foal or Newborn, Born Stained Yellow, Orange or Brownish
Newborn Foal, Strains or Pushes to Urinate
Newborn Foal, Straining to Pass Manure
Foal or Newborn, Navel or Umbilicus Seems Swollen & Firm
Foal or Newborn, Belly seems Bloated
Foal or Newborn, Fever, Rectal Temperature Greater than 102.5 Degrees
Newborn Foal, White of Eye is Red or Bloodshot
Newborn Foal, Not Nursing or Depressed
Milk Dripping from Teats of Pregnant Mare
Foal or Newborn, Under 1 Week Old has Diarrhea
Foal or Newborn, Nursing Constantly
Foaling, Mare Just Foaled, Mare & Foal Seem OK, What to Do?
Foal or Newborn, Swollen Limb or Leg
Milk Dripping from Teats of Nursing Mare
Foal Lameness, Under 1 Month Old
Foal or Newborn, Seizure or Convulsion
Foal or Newborn, Milk Draining out Nostrils
Newborn Foal, Seems Small or Underdeveloped
Pregnant or Lactating Mare's Udder Seems Small
Foal or Newborn, Accidentally Separated from Mare
Newborn Foal, Mare will Not Allow Foal to Nurse
Newborn Foal, Urine Dripping from Umbilicus or Navel
Newborn Foal, Heart Rate Abnormally Slow, Less Than 40 BPM
Rubbery Slab of Tissue Found with Placenta after Foaling, Hippomane
Foal or Newborn, Eating Manure
Foaling, Delivery Taking Place Now!
Frozen Ears, Tail or Limbs


Testing allows verification that a foal has absorbed adequate amounts of antibody. It is a simple, and relatively inexpensive test.

Early detection of failure of passive transfer allows for prompt administration of life-saving treatments.


Some of the test kits are less reliable than others.

Enough time must be allowed for antibody levels to rise to their maximal level after foaling, usually 12-24 hours.

Helpful Terms & Topics in HSVGWritten, Reviewed or Shared by Experts in Equine Health

Author: Doug Thal DVM Dipl. ABVP


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