Vet’s View: 100+ MPH, are you kidding me????

Vet’s View: 100+ MPH, are you kidding me????
Vet’s View: 100+ MPH, are you kidding me????

That is the speed of the equine cough (and sometimes the speed your veterinarian is travelling when he is late to your scheduled appointment).   But let’s talk about coughing horses.  I would guess that there are very few of you out there that have not had one of your own or know of someone in your barn that has had a horse with a cough.  To be fair to the horse, we all must realize coughing is a normal physiologic function that is necessary and healthy.  It is a protective mechanism by which the body expels normal secretions, abnormal secretions and/or foreign material from the horse’s lungs.  Horses live in and often compete in environments that are full of dust, dirt, debris, and a multitude of pollens.  They eat hay that is full of naturally occurring mold spores on a routine basis and here in the Fraser Valley we put them in box stalls at night on sawdust shavings and sometimes throughout the day where dust and molds accumulate in abundance.  So the occasional cough in a horse should not be a surprise, in fact some studies show that just being an athlete in the horse world gives you an 80% chance of having Inflammatory Airway Disease (IAD).

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So when should you worry and what are some of the possible causes?  When coughing becomes consistent and more than the occasional sporadic (i.e. throughout the day and night) then it’s possible there is more lurking beneath the surface.  If your horse develops a fever and/or has a nasal discharge along with the cough then it is important to have him examined for infectious diseases.  If your horse is coughing while exercising or if there is a drop in performance then an examination is warranted as these may be indicators that your horse’s respiratory tract is becoming increasingly more inflamed.  Sometimes when coughing there is mucous or phlegm that is produced, this means that the airways are being overcome with more inflammation and secretions than the horse is able to clear on its own.

Most coughing can be placed into one of three categories:  Infectious causes, Immunogenic causes, or Mechanical causes.  Infectious causes are usually viral or bacterial but can also be caused by fungus or parasites.

Infectious causes are usually accompanied by a nasal discharge but may or may not have a fever associated with them.  The nasal discharge can be quite variable and may be clear, white, tan, yellow or green.  Some horse look really sick while others may act completely normal.  If the upper respiratory tract is involved there may be some degree of lymph node enlargement and sensitivity while if there is lower airway involvement there may be some degree of increased respiratory rate and/or some apparent difficulty breathing.

Immunogenic causes (Recurrent Airway Obstruction ‚ÄúHeaves‚ÄĚ – RAO or Inflammatory Airway Disease ‚Äď IAD) would include any type of allergic airway cause (pollen, hay, feed etc.) or may be the result of constant exposure to dust, dirt, dry air, shavings or as a sequelae of a previous respiratory infection.¬† There usually is no increase in body temperature and the discharge is usually absent but may be clear or look more mucoid in consistency.¬† The coughs are usually dry and may only be heard while exercising or they can be more productive and occur spontaneously throughout the day.

Mechanical causes may consist of laryngeal or pharyngeal disorders, palatal problems or tumors to name a few.  Most of these causes are usually noticed only while exercising however tumors may present like any of the above mentioned scenarios.

Treatment of coughs usually depends on the cause so having a diagnosis or a presumptive diagnosis is very important.  Many diagnostic tests are available and valuable to help direct treatment.  Routine bloodwork such as a CBC/Chemistry Panel will look for Red and White blood cell counts along with other indicators of inflammation or disease.  Serum Amyloid A (SAA) can help differentiate between infections or other causes as SAA becomes elevated in infections quite rapidly.  Pharyngeal washes and tracheal washes submitted for culture/sensitivity and PCR testing will identify specific bacteria or viruses that may be present while a broncho-alveolar lavage helps determine the types of cells that are being secreted into the lungs to help further direct the appropriate drugs one may choose to help treat an immunogenic (allergic) condition.  Ultrasound, Radiographs and Endoscopy are also utilized to investigate identify and quantify respiratory disease in the horse.

Most coughs are treated with patience as the horses own defense mechanisms usually takes care of the majority of the problems but other treatments for those unfortunate enough to have a more significant problem may include antibiotics, antifungals, bronchodilators, and/or corticosteroids.  The latter two may be administered orally, by injection or sometimes via an inhaler.

However the most important factor in improving your horses’ health is to decrease the environmental dust dirt and molds that they are exposed to daily.  Completely removing hay from the diet can help accomplish this goal. Horses can be fed pelleted complete feeds or soaked hay cubes.  There is some good evidence that feeding Omega 3 fatty acids along with hay cubes only is very effective at reducing inflammation in the airways of horses.

Ideally they would be turned out 24hrs/day for improved air circulation.  For a multitude of reasons, if this cannot be accomplished then below are some recommendations by the American College of Veterinary Internal Medicine on reducing airway irritants:  (http://www.acvim.org/Portals/0/PDF/AnimalOwnerFactSheets/LAIM/LAIM Inflammatory Airway Disease in Horses.pdf)

  • Remove horses from the barn prior to cleaning stalls and feeding.
  • Keep horses out of the barn until at least 1 hour after chores are completed.
  • Bed horses on wood shavings, cardboard or pelleted bedding versus straw or hay
  • Feed hay from the ground and wet it down
  • Provide good ventilation.
  • Keep stall windows and barn doors open to allow fresh air flow.
  • Pick up clutter in the barn and tack room to decrease areas where dust can settle in the environment.

 

 

 

Eric Martin DVM, CAc, cVSMT: Dr. Martin pursued veterinary medicine by attending Kansas State University Veterinary School. While there, he was given the opportunity to further his education through externships in the northeast, at Mid Atlantic Equine Medical Center. After graduating, he accepted an associate position in a sport horse practice in central Connecticut where he worked for 3 years prior to moving to the Fraser Valley in British Columbia. He pursued his interest in the sport horse world by becoming certified in Acupuncture and Chiropractic procedures.