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	ARS Announcement Animal Reproduction Systems Product Spotlight
	Rapid Foal IgG Testing Identify Foals with Failure of Passive Transfer using an alternate calibration for the the ARS 590 or 591 Densimeter. Validated Turbidimetric Immunoassay from Animal Reproduction Systems ARS Foal IgG Test offers:
	* Accurate repeatable results reported in mg/dl * Test is rapid and easy to perform * However, in some foals, neurosteroid levels remain elevated for days and affected foals exhibit decreased awareness of their environment, decreased affinity for the mare, decreased interest or ability to nurse and are generally in an obtunded or stuporous mental state * Utilizes existing equipment available at many equine reproduction facilities * Provides critical information on passive transfer for medical management of foals
	Newborn foals are dependent on maternal antibodies absorbed following ingestion of colostrum in the first few hours of life for immune protection.  No significant transplacental transfer of antibodies occurs in utero.  Failure of passive transfer (FPT) of maternal antibodies places the foal at significant risk of infectious diseases. An IgG concentration of = 800 mg/dl is considered optimal.  Plasma IgG levels 400 to 800 mg/dl may be adequate for healthy foals in a clean environment with minimal exposure to pathogens. However, an IgG between 400 and 800 mg/dl may be inadequate for compromised or systemically ill foals. An IgG concentration less than 400 at 24 hours of age indicates failure of passive transfer (Table 1). Table 1.  Interpretation of plasma IgG concentrations in foals relative to passive transfer.
	Foal Plasma IgG Concentration Interpretation > 800 mg/dl Optimal passive transfer 400 to 800 mg/dl Adequate passive transfer 200 to 400 mg/dl Partial failure of passive transfer < 200 mg/dl Complete failure of passive transfer
	Early testing for antibody levels in a neonatal foal can identify potential cases of FPT and allow for early intervention and medical management.  A blood sample can be collected at approximately 12 hours after birth and evaluated for IgG concentration.
	* IgG levels > 800 mg/dl - indicate that adequate passive transfer has already occurred and no antibody supplementation is indicated in most clinical situations * IgG levels 400 to 800 mg/dl - indicates that moderate antibody transfer has occurred by 12 hours of age and additional uptake is likely by 24 hours of age; the need for intervention and antibody supplementation is dependent on potential pathogen exposure, medical condition of the foal and other factors * IgG levels < 400 mg/dl - indicates that only a small amount of antibodies has been absorbed by 12 hours and oral administration of supplemental frozen-thawed colostrum or other a commercial equine IgG product is indicated; an alternative would be intravenous administration of plasma to provide additional antibodies * IgG levels < 200 mg/dl - indicates that the foal has not nursed colostrum at all and is at high risk of failure of passive transfer (low IgG at 24 hours of age) and susceptible to infectious disease
	Testing at = 24 hours of age will determine the final extent of passive antibody absorption as no significant amount of antibodies is absorbed after 24 hours of age.  Foals greater than 24 hours of age identified with failure of passive transfer require intravenous administration of plasma to increase blood antibody levels as oral absorption is negligible and therefore not indicated. It is recommended that the IgG level of an at-risk foal be re-evaluated the day after administration of colostrum or plasma to determine for additional supplementation.   Evaluation Techniques Diagnostic tests for evaluation of plasma IgG levels in foals include the single radial immunodiffusion (SRID), glutaraldehyde coagulation (GC), zinc sulfate turbidity test (ZST), latex agglutination test (LAT), enzyme immunoassay (EIA) and turbidimetric immunoassay (TIA).  The SRID test is the most accurate test for quantitative measurement of serum or plasma antibody levels.  However, results are generally not available for 24 hours or more making it impractical for routine use when rapid results are required.  Enzyme immunoassays are semi-quantitative tests that utilize a color change to estimate IgG concentrations in foal blood or plasma.      The ARS Foal IgG Test is a turbidimetric immunoassay based on a specific antigen-antibody reaction in which goat anti-equine IgG binds to equine IgG in foal plasma.  The concentration of foal IgG is determined by the degree of turbidity, measured as percent light transmission in a calibrated spectrophotometer (Densimeter).  The ARS Foal IgG Test was validated against the SRID test. Assay Steps:
	* A small volume (i.e. 1 ml) of foal blood is collected and transferred into a EDTA blood tube * 25 µl of foal plasma is added to a specific volume of assay buffer within a cuvette * 180 µl of the diluted plasma is transferred into a second cuvette containing buffer in the final dilution step * The loaded cuvette is placed into a Densimeter and the ‘ZERO’ button is pressed; the unit will determine the percent light transmission through the cuvette with the diluted foal plasma * 180 µl of goat anti-equine IgG is subsequently added to the second cuvette and gently mixed * The goat anti-equine IgG will form immune complexes with equine IgG in the diluted foal sample in a dose-dependent manner * The cuvette is placed back into the Densimeter and the ‘COUNT’ button is pressed; a countdown for a 5 minute incubation period is initiated * At the end of the incubation period, the unit will again determine the percent light transmission through the cuvette; the greater the foal IgG, the lower the percent light transmission * The computer within the Densimeter will automatically convert the difference in percent light transmission into IgG concentration and display the results in mg/dl
	The Foal IgG calibration can be added to any 590 or 591 Densimeter. Upgrade information for the 591 Densimeter can be found here. Upgrade information for the 590 Densimeter can be found here. Supplies for the IgG test can be found here. Please visit www.arssales.com/equine for information on all ARS products. For more information call us at 1-800-300-5143 or visit our web site at www.arssales.com. Comments/questions/suggestions - e-mail them to sales@arssales.com