Dr. Jeske Noordergraaf

February 2006

Horses can develop breathing problems year around.  Equine influenza or other respiratory viruses such as rhinopneumonitis or “rhino”, and bacterial infections can strike a horse regardless of the time of year.  In the winter horses tend to travel less and be less frequently exposed to new horses, thus reducing the spread of contagious diseases.  If a horse is kept in a heated closed barn, however, the barn can be a source of infections, as moist and warm conditions are appreciated by bacteria and viruses. 

Taking the vital signs of a horse with a snotty nose or a rapid breathing rate is a good place to begin.  Normal rectal temperature for a horse is approximately 99-100°F and the normal breathing rate is 16 breaths per minute.  An elevated temperature often corresponds with an infection, but not necessarily with the need for antibiotics.  Antibiotics kill bacteria but not viruses.  Since the cause can be either bacterial or viral, blood work may be needed to help determine which one is the culprit.  If the horse is eating and drinking well and quickly seems to be improving, we will often let the body fight off the infection rather than prescribe antibiotics. 

Listening to the lungs helps veterinarians determine whether the problem is pneumonia, chronic obstructive pulmonary disease (heaves), or possibly something else.  Blood work is also helpful in determining the severity and the lungs can be ultrasounded to determine if there are abscesses or fluid present.  Chest x-rays are also an option, especially in foals.  Enlarged lymph nodes may indicate that the cause is strangles, which is a highly contagious bacterial infection.

This time of year the most common cause of breathing problems is chronic obstructive pulmonary disease caused by bad hay, often round bales.  I hate round bales, not because I hate more work, but because most of the heavey horses we see are being fed round bales.  Unless these round bales were stored inside, they are often dusty and moldy.  When you look at a horse’s mouth, the intended destination for food, it is easy to see why dusty hay causes problems.  When a horse pulls out a mouthful of bad hay, the dust and mold go right into the nose and down into the lungs, causing allergic problems.  Once the immune system is geared up to fight this, it takes less time each time to trigger the allergic response.  Although there are very effective medications to treat this, prevention is the best and least expensive. 

Management is the most important factor in keeping your horse healthy.  Feeding good hay is critical.  Open a bale and smell it yourself.  Keep your horse outside as much as possible and have good ventilation in the barn.  Isolate new horses for several weeks to make sure they are healthy and vaccinate for the diseases for which your horse may be  at risk. 

People can wash their hands to prevent disease.   Good management and an appropriate vaccination schedule can keep our horses healthy - even when they are out and about.