Case of the Month
RECURRENT AIRWAY OBSTRUCTION (RAO)
Case History – “B” is a 7 year old Quarter Horse gelding who is not new to the property. Has been coughing in the morning off and on for about 1-2 weeks. Never coughed much while being ridden. Occasionally has clear to whitish nasal discharge. No history of respiratory issues or pneumonia. The coughing in the morning has also been increasing in frequency.
Exam- BCS 5/8, Tempterature = 99.8 F, Pulse = 40, Respiratory Rate = 24 (normal is 8-12 breaths/minute) with prolonged expiratory phase (breathing out), gums pink and moist, no evidence of nasal discharge. See video- watch how B appears to push air from chest actively, and how it takes longer than average.
Lung auscultation revealed areas of mildly increased breath sounds, the majority of the lung fields bilaterally had expiratory wheezes of varying intensity. The wheezes were also auscultable over the trachea. No crackles or evidence of tracheal mucus was heard.
Diagnosis & Treatment- Lower airway inflammation that is referred to as RAO- Recurrent Airway Obstruction. This disease is characterized by an abnormal breathing pattern at rest- the rate and effort are increased. There can also be bouts of coughing, clear to whitish nasal discharge, and decreased athletic performance. This disease is often diagnosed by clinical signs, but several diagnostic procedures can be performed to differentiate it from other lung issues- Inflammatory Airway Disease, pneumonia, COPD/Heaves. These include upper airway endoscopy, complete blood count, transtracheal wash, and broncho-alveolar lavage.
In B’s case, the relatively short duration of clinical signs, his age, and presence if the abnormal breathing pattern lead us to the diagnosis of Recurrent Airway Obstruction. This disease is a lifetime issue that will need attention and treatment on a regular basis. The largest factor in success of treatment is environmental changes/management. RAO symptoms are caused by the lung’s reaction to allergens/dusts. Dust control is critical in management. These horses do best by having increased time outside – if possible, all-day turnout is best. Lighter dust beddings (bagged shavings), and soaking hay to decrease dust are very important. In some cases the horse must be placed on a complete pelleted feed if reactions to hay dust are too strong.
Pharmacological treatment involves corticosteroids and bronchodilators of various delivery methods. The inhaled medications are more efficacious, however their costs and acceptance of the mask by some horses is prohibitive. Oral medications are the most commonly used, and relatively simple to administer. Some horses have more active disease in the spring, summer, or fall. Often the more seasonally affected horses can be weaned off medication in their non-trigger months.
Acupuncture/herbal treatments, and inhalant therapies such as a transpirator or nebulizer are useful supportive therapies as well.
Every horse responds to therapy differently, so every case will progress in a different manner. That is why it is important to have a good relationship with your veterinarian, and have routine check-ups to ensure disease is staying under control. RAO is a waxing-waning disease that has bouts of activity and inactivity. It is possible to manage your horse effectively to ensure there is minimal reoccurrence of clinical signs with dedication to environmental adjustments