Failure of Passive Transfer
Learn what the condition is, how it may be detected early, how it is treated or managed, and which breeds or species are linked to it.
Condition snapshot
A concise guide to the condition’s pattern, detection, management and urgency.
This snapshot is a general guide, not a diagnosis or treatment plan. New, severe or worsening signs require veterinary assessment.
About the condition
Failure of passive transfer occurs when a newborn foal does not acquire enough protective maternal immunoglobulin, chiefly IgG, from colostrum. The equine placenta prevents meaningful antibody transfer before birth, so the foal is born immunologically vulnerable. Intestinal absorption is greatest during the first hours and falls rapidly, becoming negligible by roughly 24 hours.
Failure can result from poor-quality colostrum, premature lactation, the foal not standing or nursing, maternal rejection, weakness, prematurity or gastrointestinal disease. A mare may appear to have abundant milk while her first secretions contain too little IgG. Even adequate colostrum cannot protect the foal if intake is delayed until specialised intestinal cells have stopped absorbing intact antibodies into the circulation.
Affected foals initially may look normal. Their risk of bacterial sepsis, pneumonia, diarrhoea, infected joints, umbilical infection and meningitis rises during the first days. Failure of passive transfer itself does not cause a particular fever or swollen joint; it removes protection and allows infection to establish. Waiting for illness loses the best prevention window.
All foals should stand and nurse promptly after birth because each lost hour narrows the opportunity for intestinal antibody uptake. Premature, weak or dysmature foals have less reserve and may absorb poorly even when they reach the udder. Prognosis is excellent when protection is restored before infection, but becomes guarded once bacteria seed the bloodstream, joints, lungs, umbilicus or nervous system.
Colostrum provides concentrated antibodies only during the mare’s first secretions; ordinary milk cannot replace it later. Quality, volume and timing all matter. A vigorous foal seen at the udder may only mouth the teat or take a few ineffective swallows, while maternal leakage before birth can leave apparently full milk that no longer contains the original antibody concentration.
Screening & Early Detection
Foaling attendants document time to stand and nurse, udder filling, premature milk loss and colostrum quality measured with a validated Brix refractometer. The foal's suck, temperature, heart rate, respiration, mucous membranes, umbilicus and joints are examined. A weak or non-nursing foal is evaluated immediately rather than waiting for routine testing.
Serum IgG is commonly measured at 12–24 hours with a stall-side assay or laboratory method. Earlier testing at about 8–12 hours is valuable when oral absorption can still be used, provided a low result is repeated after intervention. Total protein or globulin is an imperfect surrogate and should not replace IgG testing in a high-risk foal.
A deficient foal is screened for sepsis with blood count, fibrinogen or serum amyloid A, glucose, lactate and blood culture as indicated. Any lameness, diarrhoea, breathing change or lethargy prompts targeted imaging, joint or cerebrospinal-fluid sampling. Testing the mare's colostrum helps prevention but does not prove how much the foal absorbed.
A repeat IgG after plasma or colostrum confirms absorption instead of assuming the calculated dose succeeded.
Treatment & Management
Before intestinal closure, a bright foal with a safe swallow may receive high-quality frozen-thawed colostrum or an appropriate commercial equine colostrum replacement. It is given promptly in divided volumes by supervised bottle or nasogastric tube. Microwave heating is avoided because it damages antibodies, and questionable donor colostrum is not used.
After about 18–24 hours, oral antibody is no longer reliably absorbed. Intravenous equine plasma is then administered, commonly one or more litres depending on size, starting IgG and product concentration. The foal is monitored closely for transfusion reaction, and IgG is rechecked after treatment because one bag may not achieve the target. Plasma does not remove an established infection.
Foals with suspected sepsis require blood culture, immediate broad-spectrum intravenous antimicrobials, fluids, glucose and organ-specific intensive care without waiting for IgG results. Clean housing, umbilical care and adequate nursing reduce exposure but cannot replace antibodies. For future foalings, mares are vaccinated on schedule, monitored for premature lactation, and a bank of tested colostrum or plasma is arranged. The successful endpoint is a clinically well foal with documented adequate IgG, not merely observed nursing.
Breeds or species affected
Akhal-Teke
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Anglo-Arabian
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Arabian
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Barb
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Caspian
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Kathiawari
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Marwari
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Shagya Arabian
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Thoroughbred
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American Quarter Horse
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American Paint Horse
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Appaloosa
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Australian Stock Horse
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Brumby
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Waler
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Morgan
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Standardbred
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American Saddlebred
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Tennessee Walking Horse
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Missouri Fox Trotter
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Rocky Mountain Horse
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Peruvian Paso
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Criollo
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Mustang
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Canadian Horse
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Andalusian
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Lusitano
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Lipizzaner
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Friesian
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Dutch Warmblood
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Hanoverian
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Holsteiner
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Oldenburg
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Westphalian
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Trakehner
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Selle Français
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Belgian Warmblood
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Danish Warmblood
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Swedish Warmblood
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Swiss Warmblood
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Australian Warmblood
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Irish Sport Horse
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Cleveland Bay
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Württemberger
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Zangersheide
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Knabstrupper
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Orlov Trotter
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Camargue
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Icelandic Horse
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Pony of the Americas
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Quarter Pony
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Miniature Horse
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Clydesdale
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Shire
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Percheron
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Belgian Draft
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Suffolk Punch
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American Cream Draft
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Ardennes
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Breton
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Boulonnais
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Comtois
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Dutch Draft
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North Swedish Horse
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Norwegian Fjord
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Haflinger
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Gypsy Cob
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Irish Draught
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Welsh Pony and Cob
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Connemara Pony
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New Forest Pony
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Dartmoor Pony
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Exmoor Pony
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Shetland Pony
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Highland Pony
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Fell Pony
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Dales Pony
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Australian Pony
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Finnhorse
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Black Forest Horse
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