An elevated concentration of irritants in the air causes measurable lung inflammation in all horses. There may or may not be a true allergic component. Continued exposure can lead to IAD (inflammatory airway disease) or RAO (recurrent airway obstruction) in susceptible horses. These conditions have a considerable impact on the horse’s comfort and performance. There may be increased risk of infectious lung disease or irreversible damage in chronic cases.
A variety of airborne substances have been implicated. Ammonia from bacterial breakdown of urea in urine is a well documented lung irritant in a variety of species. “Organic dust” is also an offender. This includes microscopic particulate matter from mites, plant material (e.g. beta-glucans), feces, bacteria and their products (endotoxin) and fungal spores.
Barns need good ventilation even in winter. If you have window condensation in the barn there’s a major ventilation problem.
A critical first step in reducing airway irritation is to guarantee good air circulation through the barn. High moisture levels indicated by window condensation suspend the irritating substances and reduced air turnover allows their concentration to increase. Other measures to take, especially if you have symptomatic horses, include:
- Pick out stall wet spots frequently and consider stall deodorizers (even kitty litter works) for ammonia control
- Store hay in a separate building
- Use wood or paper bedding rather than straw
- Do not clean stalls or sweep with horses in the barn
- Wet hay and bagged feeds before feeding
- Turn the horse out as much as possible
Several supplement ingredients can help with maintenance of normal lung function in the face of these temporary challenges. Spirulina assists in the maintenance of a normal, balanced immune response and stabilization of histamine releasing cells. MSM supports a controlled inflammatory response. Research has documented low levels of antioxidant vitamin C in IAD/RAO lung fluid and supplementation can help restore this. Jiaogulan (Gynostemma platensis) is a Chinese adaptogenic herb which supports normal airway dilation for good air flow.
The reaction to the airborne irritants and allergens generates considerable oxidative stress. All living things are equipped with the ability to produce a range of antioxidant defenses but these can be overwhelmed. When that happens, plants offer a rich source of antioxidant phytochemicals to help maintain homeostasis. These include all berries, grape seed and skins, citrus bioflavinoids which work with vitamin C, Boswellia, Turmeric, Ginger and Ginkgo.
N-acetyl-cysteine supports the horse’s ability to manufacture glutathione, an important antioxidant. As an additional benefit, it assists in maintaining a normal, watery consistency to mucus so that it can be moved out easily.
IAD and RAO are common equine respiratory conditions caused by environmental irritants. Fortunately, there are many things you can do to reduce exposure to those irritants and supplements which help the body maintain normal lung function.
Eleanor Kellon, VMD