The immune system and your animal’s eyes -- balance is key

A look at how your animal’s eye health is linked to his immune system, and how you can keep him seeing and feeling well.

Your dog or cat’s eyes are vital organs commonly attacked by outside forces (e.g. trauma, infection) and defended by his immune system. The eye is also frequently attacked by inside “dark forces” (autoimmune diseases), and only weakly defended by a compromised immune system. The eye is unique among body organs in that mild tissue damage caused by inflammation can result in vision problems and even blindness. The eye rarely forgives; often, the veterinarian is given only one brief chance to save a dog or cat’s eye. This means it’s very important to rapidly and aggressively control inflammation in an animal’s eye.

The immune system is comprised of two main parts

  1. The adaptive immune system (AIS) is mediated by B and T white blood cells that slowly recognize invaders.
  2. The innate immune system (IIS) rapidly recognizes invaders.

Ocular immune warfare is best engaged by the AIS and IIS working together.

Natural killer (NK) cells are white blood cells that are part of the AIS; they rapidly kill infected or cancer cells and regulate damage against normal cells. NK cells have long memories and “quick-triggers”; their unique ability to recognize stressed cells without using antibodies allows them to react rapidly (“kill first, ask questions later”). NK cells control immune responses and maintain balance and can “change their minds” to magnify either a beneficial immune response or reduce a destructive autoimmune response.

Immune-mediated uveitis

This autoimmune condition is the most common cause of inflammation inside the eye. About half of all uveitis cases have no identifiable cause and are termed “immune-mediated uveitis”. All uveitis is triggered by toxic free radicals generated by oxidative stress. Since the eye is an enclosed organ, a small amount of damage can potentially cause blindness.

There are three phases of uveitis. In the acute phase, a white blood cell called the neutrophil or PMN (polymorphonuclear) cell is the predominant inflammatory cell; damage or death of PMNs enhances tissue destruction and inflammation. The subacute phase is the most important because it is where immune reactions are initiated; either resolution occurs, or cell death with recurrence or chronicity is established.

Mild localized uveitis can resolve with only minimal scarring by PMNs and other white blood cell types. Severe uveitis may cause scarring with permanent damage and loss of function. Uveitis can result in blindness from cataracts, glaucoma and/or retinal detachment. Any phase of uveitis, even if apparently resolved, can become recurrent or chronic due to the immune system’s long memory.

Antioxidants help the eye fight inflammation

The delicate, complex and inflamed eye cannot battle inflammation without help. Daily lifetime administration of antioxidants and supplements that promote healing and immune system balance is imperative for canine and feline uveitis patients.

Specific antioxidants, including grapeseed extract, lutein/zeaxanthin, astaxanthin, Omega-3 fatty acids and alpha lipoic acid, can prevent, decrease and reverse ocular free radical damage. The use of specific blends of antioxidants and other supplements may help alleviate ocular tissue damage and improve cell recovery and regeneration critical for vision; and support normal NK cell function for immune system balance.