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Respiratory Disease in the Horse

Anyone that has owned a horse has probably experienced respiratory disease in some shape or fashion.  Much the same as humans, horses are prone to developing upper respiratory infections due to viral and bacterial invasion, but the two most common and troubling conditions affecting horses in today’s industry is chronic obstructive pulmonary disease (reactive airway disease) and exercise induced pulmonary hemorrhage (EIPH).  Being a veterinarian working on horses, I have certainly encountered my fair share of COPD patients as well as EIPH athletes and feel a times that these conditions are becoming more prevalent.

The respiratory tract plays a vital role in health and performance as well as day to day activity.  In the horse, air is taken in through the nasal passages, down the trachea and into the lungs were carbon dioxide is exchanged for oxygen to fuel cells.  Any problems encountered during this course of airflow can impact oxygen flow to the body, overall performance and quality of life.

Common Respiratory Problems:

  • Upper Respiratory Infections:  Often very similar to those found in people and pets, these problems are generally linked to various bacteria and viruses, including influenza and EHV.  The typical signs include febrile illness, coughing and nasal discharge.  These conditions are often viewed as being very contagious between horses, thus management and hygiene are paramount.  Treatment generally is supportive in nature with a high morbidity rate and low mortality.  In some cases of cloudy nasal discharge, antibiotics will be implemented to help clear the infection.  In those cases where the nasal discharge is clear in color, antibiotic usage is generally not warranted unless a secondary bacteria becomes a problem.
  • Laryngeal Paralysis:  This problem is more an acquired issue or genetic problem, often found in race horses.  Here we have a problem in the larynx, which is the back of the throat and entrance to the trachea or windpipe.  In terms of anatomy, we all have vocal folds which open and close the opening to the trachea, allowing air in and closing when swallowing in order to prevent food from entering the airway.  In cases of laryngeal paralysis, one of the folds fails to open partially or fully, leading to a restriction in the air flow and a ‘roaring’ type of noise upon inspiration.  This is why most of these horses are referred to as “roarers”.  The condition can be genetic or acquired, often linked with nerve damage in the neck region possibly due to improper injection technique in some instances.  Treatment is generally surgical in nature through a technique called a ‘tie back’ in which the fold is permanently left in an open position.  The downside to this procedure is that those horses are then more prone to aspiration pneumonia due to inhalation of food stuff into the airway.
  • EIPH:  Exercise induced pulmonary hemorrhage is a condition of exact unknown cause but it thought to be linked to excessive pulmonary or lung pressures, leading to rupture of small blood vessels within the lung tissue upon extreme exertion.  The condition is commonly associated with racehorses, but can be seen in any discipline with those horses that are predisposed to it.  Treatment is often viewed as supportive with the most common medication being used called Lasix®, which is a diuretic.  The theory is that with use of the diuretic, water volume is lost as urine and thus blood pressures are lowered, reducing the incidence.  For many horses, diuretic usage helps but does not fully control the problem.
  • I.A.D:  Inflammatory airway disease is a common problem, especially in young upcoming race horses. It is an inflammatory condition of the lower airways, again with an unknown cause but thought to be linked with a previous viral infection or even antigen stimulation (dust) in the environment.  In I.A.D, many times the horses exhibit ongoing coughing plus or minus a discharge.  Often the airways are irritated sufficiently enough to cause them to close up, which then inflicts performance problems due to restricted airflow and oxygen distribution.  Treatment is often supportive by using antibiotics and corticosteroids if needed.
  • C.O.P.D (RAO): Chronic obstructive pulmonary disease or recurrent airway obstruction is a common problem in some horses and breeds.  This condition is not far removed from typical asthma seen in people and is characterized by an ongoing inflammatory response within the airways, leading to airway constriction or narrowing in addition to a buildup of mucous like debris.  The condition often becomes prevalent during high antigen times of the year, including spring and summer, with more quiet times during the fall and winter.  Unfortunately, the condition is recurrent and with each flare up, continued damage is done to the lung tissue, which makes the problem more and more difficult to manage.  Typical therapies include environmental control, steroid usage and various medications to open up the airways.

Causes and Impact:

As with any condition, from my point of view, we need to look at the common denominator and see if there is anything we can do to help better manage those problems.  In the case of upper respiratory infections, any horse is predisposed, but it seems that some are more likely to develop problems than others.  It is no different than with kids or adults, some people just seem to be more sick, more often than others.  The question is is “why”?  More than likely it is some sort of immune dysfunction, which opens the door for infection.  In many cases of performance horses, the dysfunction is a result of stress.  Given this, there are two things that we can potentially manage; immune health and stress reduction.  In those cases, we will often use our EQ Immune Full Spectrum and couple it with our EQ Adapt formula if stress is a problem.

In cases of E.I.P.H, we have found great value is the use of our EQ Plus formula, helping to reduce the incidence and also often reducing the needed dosage of diuretics.  The reason for this is that in human research data, there are indications that not only are there elevated pressures, but there is an underlying weakness of the blood vessel lining, often attributed to inflammation and oxidative stress.  This weakness then makes the vessel less likely to hold up to elevated pressures.  If we control the inflammatory response properly and manage oxidative stress, then it is possible that we can secondarily improve blood vessel health.  Our EQ Total Support formula also may prove beneficial as this product not only helps to manage inflammation, but uses herbs including dandelion that have shown to possess diuretic type properties.

Those horses with I.A.D have shown beneficial responses to a double combination approach through the use of EQ Plus and the EQ Immune Full Spectrum formula.  Here again, we are not only enhancing or managing the immune response, but managing the inflammation behind the restriction of the airways.  Another option in the typical IAD equine patient is the EQ Stomach blend.  Many of these IAD horses have a dry airway and a dry cough, which further creates irritation.  They have little to no discharge regarding phlegm.  The EQ Stomach formula contains high levels of Marshmallow and Aloe, which both soothe and moisturize the body and specifically benefit the airways.

C.O.P.D has proven to be a tough situation to handle in most horses and is best managed in early stages before lung damage occurs.  In our patients, we have found the best benefits by using our EQ Total Support formula, which addresses inflammation and helps to dry up mucous accumulation through the diuretic effects of dandelion.  In many cases of allergies, the root cause is thought to be linked to digestion and gut health.  The EQ Total Support helps to improve gut health through the action of many herbs and in one of our research trials, over 80% of patients benefited with improved quality of health within a short period of time.  In other patients, or those that fail to respond to the EQ Total Support, we have had good results by combining our EQ Plus and the EQ Immune Full Spectrum.  The EQ Immune formula can also be combined with the EQ Total Support for enhanced immune support.

In my practice, I have conducted several field trials evaluating inflammation and oxidative stress in a variety of conditions affecting horses.  What I have found is that in many of these conditions there is a definite inflammatory component which is also accompanied by oxidative stress.  Now, one has to remember that the basics of oxidative stress is that there is an abundance of free radicals generated which can result in cellular damage.  In most cases, the free radicals are neutralized per se by the presence of antioxidants.  What I feel is occurring is that either these horses are not consuming enough antioxidants or the right combination of antioxidants or they are experiencing an overwhelming level of free radicals that is quickly depleting the stores.  I believe that one of the most important aspects of these conditions to address is the inflammation, which I don’t feel is being addressed adequately with today’s therapies.  Race and competition horses are under a tremendous amount of physical and mental strain, which can contribute to inflammation levels.  Those horses afflicted by COPD are generally systemically inflamed in my opinion, in which we are just seeing the evidence manifested in the respiratory disease.  Today’s therapies are helping to control a small percentage of these patients and given this, we must ask what more can be done especially considering the potential side effects of the medications being used.  In the race horse industry and other disciplines, medication debates are constantly being raised.  We need to seek out other viable options not only in terms of therapies, but to also potentially use as preventative to improve the health of these animals.  What we are seeing clinically is a direct manifestation of what is occurring deep within and a sign of imbalance to one degree or another.

In the end, I do believe that we can impact the course of many clinical respiratory problems in the horse, helping to make them more manageable and improve the quality of life for the patient.  There may not be one answer to every solution, but if we keep playing, an answer is always there.

Just my thoughts.

Tom Schell, D.V.M.

Nouvelle Research, Inc.

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