The Body’s Defenders Part III of a Six-Part Series

The immune system is a brilliantly multi-faceted and highly effective structure that protects the horse, as it does every mammal, against exposure to the billions of microorganisms (viruses, bacteria, protozoa) and allergens encountered in everyday life; and protects and restores organs, muscles, joints, and bones from injuries as small as minor cuts and strained muscles, to more damaging trauma.

The Front Lines

The first layer of defense, the innate immune system, consists of physical barriers to infection, along with immune cells and other complementary proteins and cytokines.  These protective physical barriers include the skin, saliva, tears, and the mucus secretions of the intestinal, respiratory, and reproductive systems.

The defenders are armed by the immune system with a huge arsenal of cells, some of which take on all intruders (the innate system), and others that are focused on highly specific targets (the acquired immune system).  Some work by direct physical contact, and others release chemical messengers (cytokines).

The body is constantly coming in contact with microorganisms both good and bad, and the immune system works diligently to distinguish between the pathogens (the bad invaders) and the good allies that are useful for the body.  This sorting process utilizes the immune system’s high tech detection mechanism that ‘scans’ all microorganisms.  The good ones are then let through the line of defense so that they can become allies, and the bad ones are either killed or simply eaten by the defenders. 

Gathering Information

The longer term, or acquired immune system, then remembers which are good and which are bad and forms a ‘database’ to store this information so that the next time it is challenged it can recognize the invaders and spring into action with a rapid response team (antibodies).  Produced by plasma cells, these antibodies can quickly identify and neutralize the pathogens.

The database needs only to store a few of each kind of antibody, because it takes just a few to recognize a possible enemy.  When an invader does appear on the scene, the few immune cells that recognize it are able to respond by instantly multiplying into a full-scale army of antibodies.  After their job is done, most of the cells fade away, leaving a few sentries behind to watch for future attacks.  Thus, the immune system is designed to respond to a stress such as disease or injury efficiently and effectively, and then return to a normal state of balance.  If, as in the case of a chronic illness or debilitating injury, the body is unable to recover quickly, the immune system can remain activated too long, causing loss of body condition. 

When a horse becomes sick or injured, the immune system sends messages to speed up metabolism rate, induce swelling (inflammation), and raise the body temperature (fever) to kill the invaders.  This short term inflammation generated by a properly functioning immune system, though it causes pain, can be beneficial, because it triggers undamaged cells in a damaged area of the body to swell, which can protect them against damage by the invading pathogens. 

If things get out of balance, and the immune response and the discomfort associated with inflammation last too long, it can be harmful because it requires a lot of nutrients (protein and energy) just to support the immune response, thereby depleting the pool of nutrients that the body needs to support growth and other normal bodily functions.  When you add to that the lack of appetite associated with illness or pain, the supply of nutrients is further compromised.

Plasma Products Can Help

Immune responses comes in all sizes, depending on the severity of the episode that triggers them.  Joint deterioration, wounds that won’t heal because of lack of vasculature, infectious disease, trauma, minor abrasions . . . all provoke an immune response tailored to the need.  And as discussed in Part II of this series, plasma products are increasingly coming into use with documented success, to promote healing in acute injuries, to block inflammation in chronic cases, and to provide relief from stress.

The performance horse can develop muscle soreness, breathing problems, and intestinal caused by a normal immune response to the stress of a rigorous training program, frequent travel, or tight schedules.  Serum-based bioactive proteins, used with profound success in farm animals for decades, and introduced to the equine market in 2014 as LIFELINE® Equine Performance Supplements, are specifically designed to target the top-level equine athlete.  The bioactive proteins in LIFELINE® have proven effective in supporting a normal immune system, thereby reducing the stress-induced overstimulation that causes this multi-systemic discomfort, allowing the hard-working performance horse to do what he/she does best.           

Next week, Part Four will examine common stressors for horses, and the immune system’s reaction to that stress.