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Lower Respiratory Diseases in the Horse

August 2019 - Equine Nutrition

With so many supplements and grain options, how should you know what to feed? Join us this month as our expert, Dr. Alison Cornwall answers your questions concerning equine nutrition.



Click here to read this month's questions and answers.

Lower Respiratory Diseases in the Horse


  1. My 23-year-old Tennessee Walking Horse gelding started coughing in October to which my veterinarian recommended Ventipulmin. Unfortunately, the medication was not helpful. He is currently on herbal remedies, which also don’t seem to be helping. My veterinarian has now recommended Zyrtec. Question is....Zyrtec everyday? And for how long? (View Answer)

    Thank you for your question. I'm afraid I don't have a specific answer for you. In general, Zyrtec, at an appropriate dose, is generally quite safe in our equine patients. However, you must remember that anything (even water) at the wrong dose/duration can be detrimental/toxic. The duration of administration on Zyrtec really should be based on your horse's clinical signs and repeated examinations by your veterinarian. If your horse continues to cough, I recommend further diagnostic tests to first evaluate the respiratory system. This can include a complete physical exam with a rebreathing exam (placing a large bag over the nostrils and mouth to stimulate the horse to take a deep breath) that allows us to list/auscultate the lungs very carefully for abnormalities. You and your vet might also consider routine bloodwork, ultrasonography of the chest, or even a bronchoalveolar lavage (BAL) to evaluate the fluid cell populations in the lungs. This information can give clues as to whether or not your horse suffers from a form of equine asthma or another condition that might warrant a different approach to therapy. Biggest takeaway - work closely with your veterinarian who knows your horse best and is able to re-evaluate the cough condition. Lynn Martin, DVM, MPH, DACVIM, University of Missouri, College of Veterinary Medicine

  2. I own a 17-year-old Quarter horse gelding that is lightly ridden three days a week for about 40 minutes each ride. When I begin riding him at only a walk, he is fine. As soon as he goes into a trot, he begins to cough. The cough is a dry, hacking long cough that continues for about 2-3 minutes. Then it disappears and he trots and lopes as if nothing is wrong. He does not cough unless he is being ridden. Free running or lunging does not bring it on either. I have him examined annually by my equine veterinarian and checks healthy. Is this something that I should be worrying about? (View Answer)

    Thank you for your question. Overall, it sounds like your horse is very well cared for and has maintained optimal health. Considering your horse's age, I would recommend having the gelding evaluated a bit further, especially if coughing is new within the past weeks, months, or even years. Coughing can be caused by many things including environmental dust causing irritation or exacerbation of an asthmatic condition, or it can be due to masses or structural changes in the nasal passages or throat region. Based on the information you shared, an infectious cause seems less likely at this point. You should work with your veterinarian to have diagnostic tests performed. Based on a thorough physical exam, including a rebreathing exam (placing a large bag over the nostrils and mouth to stimulate the horse to take a deep breath), your veterinarian may be able to detect subtle changes in nasal discharge, ability to recover from the rebreathing exam or abnormal sounds in the lungs or upper airway that will guide further diagnostic testing recommendations (such as airway endoscopy, chest ultrasound, bronchoalveolar lavage, etc.). Routine bloodwork is always nice to have on record for our aging patients, including measurement of ACTH levels for monitoring pituitary pars intermedia dysfunction (PPID). Best case scenario, you will not find any abnormalities with further investigation of the coughing, but it is possible there is an underlying condition that could be treated to improve quality and longevity of life. Lynn Martin, DVM, MPH, DACVIM, University of Missouri, College of Veterinary Medicine

  3. Can a horse with a career in racing and a diagnosis of EIPH lead to chronic airways disease from the episodes of EIPH? (View Answer)

    Interestingly, research has generally focused on the concurrent presence of exercise induced pulmonary hemorrhage (EIPH) and chronic airway disease/equine asthma (inflammatory airway disease [IAD] or recurrent airway obstruction [RAO/"heaves"]) and not long term studies that identify whether one condition leads to the other. So your question is an excellent one of which I can't give you a definitive answer. What current research tells us about concurrent disease is conflicting, in that one study says the risk of EIPH is increased with the presence of lower airway inflammation, while other studies have found no association between EIPH and airway inflammation or tracheal mucus scores. I think what is important to remember is that bleeding into the lungs is clearly abnormal and creates an abnormal environment that can provoke a mild inflammatory response, resulting in macrophages (a type of white blood cell) to come to the site and clean up the blood. However, whether this leads to chronic lower airway diseases down the road is unknown. If you have a horse with known EIPH, I recommend keeping watch for common signs of mild-moderate equine asthma (IAD) including occasional coughing and poor performance. If the condition is suspected, have your veterinarian perform a bronchoalveolar lavage to collect a fluid sample for analysis of the cell populations. This is how we diagnose equine asthmatic conditions. Lynn Martin, DVM, MPH, DACVIM, University of Missouri, College of Veterinary Medicine