IgG tests, what are they and why are they important?

IgG tests, what are they and why are they important? 

An IgG test is a simple blood test used to check immunoglobulin levels in foals. It is generally performed on a newborn foal approximately 18-24 hours after birth. The IgG test ensures the new foal has absorbed sufficient antibodies from its mother through that first important milk, colostrum. 

The absorption of the antibodies from the milk is called passive transfer. When a foal fails to absorb enough antibodies, it can be for a number of reasons. 

• The mare had poor-quality colostrum 

• She may have run milk for several days before giving birth 

• Foal failed to drink or absorb the colostrum in those vital first few hours. 

So why is this so important?  

The mare’s colostrum provides antibodies to the foal that are vital in those first few days after birth, especially until the foal can produce its own and develop a healthy immune system. The antibodies help the foal to fight off infections, and without them, a newborn foal has a lower chance of surviving those first few days.  

A foal should stand within 1-2 hours after birth and they need to be drinking soon after this. A foal’s ability to absorb the immunoglobulin proteins from colostrum is best at between 6-8 hours after birth. If you suspect your foal has not been able to absorb what it needs from the milk, or that your mare had poor quality milk, or ran milk prior to birth, there are several things that can be done with the assistance of your veterinarian. However time is of the essence, and the window for some treatments is narrow, so if you have any concerns, seek support immediately. 

There are a few things that you can do to try to help ensure passive transfer occurs and your foal gets everything they need. 

• Ensure the foal drinks in those vital few hours after birth 

• Allow the foal to nurse frequently 

• Test the mare’s milk just prior to birth (there are tests available for this, speak with your veterinarian for assistance) 

• Collect colostrum and freeze if the mare does run milk in the days leading up to birth or have some already in the freezer in case needed.  

• Have an IgG test and post-foal exam performed by the veterinarian at approximately 18-24 hours old. 

• Ensure the mare is provided with a well-balanced nutritional diet during pregnancy 

Always seek the advice and assistance of your veterinarian or a qualified professional to help navigate those important first few hours after and days leading up to the arrival of your foal. Proper preparation will allow the best start to life for your little one!