The bacteria that is most commonly associated with pneumonia or infections in the respiratory system in horses is the Streptococcal bacteria group. These microscopic bacteria are found in the air and in healthy horses they are breathed in and destroyed by the immune system, not resulting in any infections or problems. In unhealthy horses or horses that are weak, fatigued or stressed or horses that are exposed to huge number of the Streptococcal bacteria at one time the body may not be able to fight off the bacteria, resulting in pneumonia.
Horses that are more likely to develop pneumonia include young foals with poorly developed immune systems, over trained or over worked horses, horses that are kept in overcrowded stables or pastures or horse that are trailered long distances and stressed. Of course horses that already have a pre-existing health condition are also much more at risk, as are horses that have chronic respiratory problems, worms, or problems with fluid on the lungs or esophageal damage from choke.
The signs of pneumonia in horses are very similar to the signs of the disease in humans. The horse will be very tired and lethargic, not want to eat, suffer rapid weight loss, run a mild to high fever, cough, have a watery to thick, bad smelling discharge from the nose, have problems breathing or breath in a rapid, panting like manner. Often when horses with pneumonia cough they cough up mucous material from the lungs that they will swallow. Swollen glands under the jaw will be easily felt in the advanced stages of pneumonia and the horse will not want to exercise or move. He or she will usually have a dull appearance to the eyes and will be disinterested in what is going on around them.
Diagnosis includes listening to the lungs, taking samples of lung fluid to check for the presence of Streptococcal bacteria, completing an ultra-sound of the lungs to check for fluid build-up as well as completing a blood test to check for other health conditions.
Most cases of pneumonia will respond well to a broad spectrum antibiotic that will be prescribed for a week to a month or longer, depending on how the horse responds. Always complete the full treatment with the antibiotics even if the horse appears to be cured prior to stopping the medication. If you don't completely eradicate the bacteria you will have an ongoing respiratory problem with the bacterial building up a resistance to the antibiotics.
Stabling the horse in a warm, dry area is important, as is providing highly palatable good quality feeds that are free from dust. Any dust or mold is likely to trigger coughing, making the condition worse. On warm, dry days the horse could be turned out but should be isolated from other horses, waterers and feed sources to prevent possible spreading of the bacteria. Provide lots of clear, fresh water at all times.
Avoid trailering or exercising your horse during the recovery period and carefully regulate and monitor any return to competition or work for signs of reoccurrence or respiratory difficulty.