What is Small Airway Inflammatory Disease?
Respiratory infections and diseases of all kinds are common in horses due to their dusty living, working, and eating conditions. Almost all of these can produce airway inflammation, sometimes severe. SAID usually starts out as a mild cough, but since there is no fever it often gets overlooked until it progresses to the more serious form of small airway inflammatory disease, which is recurrent airway obstruction. One of the earliest signs of SAID is a cough at the beginning of exercise. If your horse has a recurrent cough without fever, there is a good chance it is caused by SAID. To be sure, it is best to see a veterinarian right away, even if the cough is mild. Delaying treatment may cause damage to the airway, causing RAO.
Small airway inflammatory disease (SAID) in horses is a respiratory illness that can turn into a more serious condition called recurrent airway obstruction (RAO), also known as heaves. Airway inflammation is not uncommon in horses and there are many causes and types of respiratory illnesses. The inflammation caused by SAID and RAO is graded 1-4 according to the degree of severity. There are two main categories of respiratory diseases, which include noninfectious and infectious. Small airway inflammatory disease is the most common noninfectious respiratory disease in horses. Left untreated, this condition gets worse and eventually becomes recurrent airway obstruction, which is similar to emphysema.
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Symptoms of Small Airway Inflammatory Disease in Horses
The signs of small airway inflammatory disease are similar to asthma symptoms, becoming worse in time and may progress to recurrent airway obstruction, with more serious symptoms. These may include:
Small Airway Inflammatory Disease
- Chronic cough (most often when exercising)
- Mucous in throat
- Frequent inability to tolerate exercise
- Poor racing performance
Recurrent Airway Obstruction
- Worsening cough
- Flaring nostrils and pushing to breathe
- Nasal discharge (runny nose)
- Difficult breathing
Causes of Small Airway Inflammatory Disease in Horses
The causes of small airway inflammatory disease varies and may be environmental or due to previous respiratory infections or injuries. Some of the most often reported causes of SAID are:
- Air pollution such as gases or smoke
- Breathing in dust from hay stored in the stable
- Exercising or running in dusty conditions
- Low quality air filtration
- Mold or fungus in the barn or stable
- Previous respiratory infections
Diagnosis of Small Airway Inflammatory Disease in Horses
A standing physical will be done when the veterinarian arrives, with an auscultation of the lungs using a stethoscope. You will be asked to walk and trot your horse and the veterinary caregiver will check the lungs again, noting changes. Once that is done, a detailed physical examination will be performed, which includes reflexes, body temperature, mucous membrane color, capillary refill time, blood pressure, respiration, and heart rate.
In addition, an endoscopy will be done to check the amount of mucus in your horse’s lungs before and after exercise. This is done with an endoscope, which is a long, thin flexible tube with a fiber optic light and camera on the end. It will be inserted into your horse’s nostril and down into the trachea and the upper airway. Your horse will be under mild sedation during the procedure. A bronchoalveolar lavage (BAL) will probably be done as well, using the endoscope to flush the lungs with saline. The fluid will be suctioned out and microscopically analyzed to rule out infections or other conditions. Laboratory tests needed include blood gases, complete blood count, serum chemical analysis, blood cultures, and urinalysis. Lastly, chest x-rays will be done to rule out other lung diseases. If necessary, an ultrasound, CT scan, and MRI may be used to get a better view.
Treatment of Small Airway Inflammatory Disease in Horses
Treating SAID depends on the cause and severity of the condition. Some of the treatment plans include breathing therapy, medications, and environmental changes.
The veterinarian will clear the lungs by using aerosolized bronchodilators, prescribing the medication to take home to continue the treatments as needed, especially before exercise.
Anti-inflammatory medications and corticosteroids are often used in the treatment of small airway inflammatory disease.
Eliminate as much dust as you can by keeping the hay watered down and use bedding that has a low dust factor (such as wood shavings). Be sure to ventilate the barn or stable and try to keep your horse outside as much as possible.
Recovery of Small Airway Inflammatory Disease in Horses
Prognosis is usually good as long as you obtain treatment before any irreversible damage is done. Continue to keep your horse’s environment safe and as dust free as possible. The veterinarian should continue to monitor the lung health of your companion; keep in contact with the clinic as follow up appointments must be kept on an as recommended basis.