Summertime Coughs and Runny Eyes in Horses

During the hottest, driest days of summer, it is not unusual for horses to have some minor coughing and/or runny eyes with some mucus in the corners of their eyes. In many areas, these signs are expected every year during the hottest days. Most of the time, coughing and eye irritation during the summer are reactions to increased exposure to dust, pollens, and mold. However, it is important to not overlook potentially more serious conditions that can cause the same clinical signs and to consult your veterinarian for advice and a complete examination.

The most important rule-out for coughing during the summer is summer pasture associated recurrent airway obstruction (SPARAO).  Horses affected with SPARAO develop clinical signs of heaves (increased respiratory effort, coughing, increased respiratory rate, and nasal discharge) while turned out on pasture. Horses with heaves also often have flare-ups during the hottest time of the year.  Other key rule-outs for coughing include infectious respiratory disease (influenza, rhinopneumonitis, and strangles) or pneumonia.

When pastures are in full bloom and height, horses’ eyes can be exposed to large amounts of pollen and mold in the pasture. Dry, sparse pastures also increase dust exposure. Many horses seem to accumulate some thick, mucus-like secretions in the corners of their eyes during the summer. Ophthalmic problems can quickly develop into vision-threatening problems, so it is imperative to consult your veterinarian about any suspected problem with your horse’s eyes. Important rule-outs for ocular discharge include corneal ulcer, foreign bodies (plant fragments, dirt particles, or seed) lodged in the eye or behind the third eyelid, and obstructed nasolacrimal ducts. A complete ophthalmic examination and staining of the eye with fluorescein will reveal corneal ulceration or any foreign bodies. The nasolacrimal ducts run from the lower corner of the eyes and open near the floor of the nostrils. If the nasolacrimal ducts are not clogged, then fluorescein dye should be seen draining from the nostrils a few minutes after it is instilled into the eye. Clogged nasolacrimal ducts can be flushed from their nasal openings in standing, sedated horses.

It is not unusual for horses to show signs of allergic-type coughing and ocular discharge during the summer. It is important for horse owners to be vigilant when these signs develop and observe for any changes that can signal other, much more serious medical problems. Consult with your veterinarian to rule out other potential problems and to find out which solutions they recommend for your local area.