What To Do
Assess your horse's general health using the Whole Horse Exam (WHE) and share your findings and concerns with your vet. Before assuming disease, account for any variables that might be different- things like ambient temperature and humidity, workload relative to this horse's fitness, and whether the pattern is new or long-standing for this horse.
Time the recovery from the moment exercise stops. As a general guideline, a horse working within its normal fitness capacity in moderate conditions should show substantial improvement in rate and effort within about 15-20 minutes and approach its resting respiratory rate (commonly 8-16 breaths per minute, though normal varies by individual) within 30-60 minutes. Heat, humidity, or work beyond the horse's fitness level can reasonably extend this.
Watch the character of the breathing throughout recovery, not just the rate: nostril flaring at rest, a visible abdominal "heave" push on expiration, wheezing or noise, coughing, or nasal discharge all matter more than the raw number. Compare the event to the horse's own history — a recovery that is taking longer than it used to for the same type of work is a more meaningful red flag than a single slow recovery on an unusually hot day or after an unusually hard effort.
Use the Whole Horse Exam to check resting respiratory rate, heart rate, mucous membrane color, and temperature, and share your specific observations — timing, character, and conditions — with your vet.
What Not To Do
Don't assume a one-time slow recovery in hot weather or after unusually hard work is dangerous, but don't dismiss labored or noisy breathing, nostril flare at rest, or a worsening trend as "just being out of shape." Don't push the horse back into work before recovery is complete, and don't ignore repeated episodes just because the horse eventually recovers each time.
