Chronic lung disease known as heaves, COPD, or recurrent airway obstruction (RAO) greatly impairs the horse’s ability to breathe and to exercise. In humans, chronic lung disease is also associated with weight loss, a significant amount of which is loss of muscle mass. This is disproportionate to muscle wasting you might expect simply from not being physically active and in people is known to involve specific loss of type I muscle fibers, the kind that rely on aerobic metabolism and a ready supply of oxygen to burn fuels.
It was observed long ago that horses with chronic lung disease often have low body-condition scores, but this has often been believed to be an effect of how hard they work to breathe. A German study published in the May 2008 Journal of Veterinary Internal Medicine specifically looked at muscle biopsies from horses with chronic lung disease compared to normals and found significantly increased evidence of muscular damage and decreased glycogen stores in muscle from horses with lung disease.
The reduced ability to exercise that chronic lung disease horses have is related both to their inability to provide higher oxygen levels to fuel exercise and to actual long-term damage to their muscles. We recommend you work closely with your veterinarian to develop an effective program of supplementation and drug therapy to minimize the effects of lung disease on your horse. We have found that Spirulina, Gynostemma and antioxidant nutrients can help relieve symptoms.