Nebulizers deliver a specific dose of medication in liquid form directly into the airways for rapid effects. Systemically-administered medications often must be given in high doses in order to penetrate into the respiratory tract, which can lead to undesirable, and sometimes serious, side effects. These risks are minimized with inhalation therapy, although adverse reactions are still possible. In horses, nebulizers may be used to deliver bronchodilators, anti-inflammatories, and antimicrobials to the airways. Although there are advantages to this type of therapy, particle size, drug solubility, breathing patterns, coughing, airway secretions, and other factors can affect how well the medication is distributed to the intended target area.
Inhalation therapy is the preferred method to manage equine asthma and may also be used as adjunctive therapies to treat pneumonia and recurrent airway obstruction (heaves). A study that investigated whether administration of a bronchodilator to healthy horses prior to exercise could enhance breathing and improve performance found no significant effects on the variables measured.
There may be cause to treat horses with medication delivered by a nebulizer due to smoke inhalation or other fire-related injury, but reports of smoke inhalation injuries in horses are rare in the scientific literature. Most of what is known about smoke inhalation injury comes from human patients. Smoke inhalation in horses that have been in enclosed spaces, such as a burning barn, are likely to differ from horses that have been exposed to smoke from wildfires. It is also important to keep in mind that the material burned influences the types of particles that are in the smoke. As discussed in our Wildfire Smoke and Horses health topic, different types of wood, vegetation, plastics, house materials, and other combustibles all produce different compounds when burned. The duration of exposure to these materials also plays a role in any resulting respiratory injury.
Horses that have undergone prolonged exposure to wildfire smoke in burned areas should be closely monitored for respiratory issues. If treatment is needed, medication distributed via a nebulizer may be warranted. This should be performed under the guidance of your veterinarian. Generally, otherwise healthy horses that are exposed to poor air quality due to wildfire smoke likely will not require inhalation therapy. Limit exercise when smoke is visible and give your horse time to recover from poor air quality. It is recommended that horses return to exercise no sooner than 2 weeks post smoke-inhalation, following the clearance of the atmosphere of all smoke. If you notice that your horse is coughing or exhibiting abnormal breathing, contact your veterinarian. Also, during times of poor air quality, your veterinarian should be contacted regarding modifications in treatment regimens for horses with ongoing equine asthma.