Horse-Breeding Solutions: Plasma’s Role in Foal Health

Plasma can provide your newborn foal with antibodies in the absence of your mare’s first milk.

Born with a competent immune system, foals can begin to develop antibodies against infectious disease agents upon exposure. However, foals and all other large-animal neonates (calves, lambs, etc.) are born without circulating antibodies in their blood. They need to ingest antibody-rich colostrum within the first 12 to 24 hours of life. The colostral antibodies are absorbed into the bloodstream - a process called passive transfer of immunity - and protect against infectious diseases. The ability of the intestinal tract to absorb colostral antibodies ends by approximately 24 hours of age. Fortunately, 85 to 90 percent of foals ingest and absorb enough colostral antibodies in the first few hours of life to be protected. When foals don’t get those colostral antibodies - called failure of passive transfer - they are susceptible to infections and can die within the first few weeks after birth. Foals with partial failure of passive transfer may be at low risk if exposure to pathogens in the environment is low.

In cases where a mare leaks milk before foaling or doesn’t produce sufficient colostrum at foaling, supplemental colostrum can be given to the foal within the first 24 to 48 hours of life, and preferably within the first four to six hours for the antibodies to be absorbed . After 24 hours, an intravenous plasma transfusion is the only way to provide a foal with antibodies. Plasma is the unclotted fluid portion of blood without the cellular components, such as red and white blood cells.

During breeding season, orphan foals may present a challenge to owners. Order the AQHA Orphan Foal Care report to explore the many options you have when it comes to caring for an orphan foal.

Plasma contains proteins (antibodies, albumen and fibrinogens), ions (sodium, chloride and potassium), nutrients (glucose and amino acids), coagulation factors complement, antitoxins, hormones and many other substances. Foals are given plasma to prevent infectious disease or to treat an infection.

After 24 Hours

Plasma is obtained from the blood of vaccinated, healthy horses. Equine plasma is available in one-liter units, which can be frozen for 12 to 24 months. Frozen plasma should be thawed in a warm-water bath. Avoid thawing plasma in a microwave or a high-temperature bath since either can result in damage to plasma proteins or antibodies. Thawed plasma warmed to approximately 98.6 degrees F is administered through a catheter placed into the jugular vein. Administer the first 50 to 100 milliliters of plasma slowly and monitor the foal for reactions (increased heart rate, respiratory rate, hives or convulsions). A single unit will usually increase the antibody level in an average-size foal. A foal with failure of passive transfer might require two liters or more of plasma to increase the blood antibody level, and a foal with partial failure of passive transfer might require only one liter.

In the event of an orphan foal, there are certain crucial steps you must take within the first few hours of the foal’s life. Review the steps in the AQHA Orphan Foal Care report.

Plasma is also used with antibiotics to treat neonatal septicemia, a life-threatening condition in which pathogenic bacteria are present in the circulating blood of young foals. Plasma harvested from horses vaccinated against Rhodococcus equi is given to foals to protect against R. equi-associated diseases (pneumonia and enterocolitis are examples). Inhalation of contaminated dust particles and ingestion are the main routes of infection, which occur within the first few days of life. Plasma should be administered before exposure or infection. Foals on farms with endemic R. equi are often administered one liter of hyperimmune R. equi plasma within the first 24 hours of life and a second liter at four weeks of age. A majority of clinical studies and anecdotal opinions indicate that plasma therapy will reduce the incidence of clinical disease by 30 to 40 percent and decrease the severity of diseases in foals that are clinically affected. Other studies have reported that plasma does not significantly reduce the incidence of R. equi pneumonia.

AQHA Member Benefit Spotlight

Foaling season is upon us, and we look forward to helping you register your new foals! AQHA members get discounted prices on registration. Be sure to register by your foal’s 7-month birthday for the lowest fee. Register your foals online or fax in your form. AQHA Customer Service is here to help with any questions. 806-376-4811.