Respiratory conditions in the horse are very common, but present in many forms. As horse owners, you may be familiar with terms including allergies, inflammatory airway disease (IAD) and chronic obstructive pulmonary disease (COPD). These terms get tossed around quite often and in many cases, despite the final diagnosis, we fail to see the connection between all of them and the possibility that one can progress to another over time.
In most cases, a subtle cough is the first clinical problem, quite possibly only present when first ridden or maybe the cough is noted only briefly when lunged in a dusty arena. In many of these early stage cases, the cough quickly dissappates and the horse seems to improve after a few strides. The cough is usually productive, meaning that they seem to cough up phlegm, but in other cases, the cough can be more dry or less productive in nature. In the cases, where there is phlegm being coughed up, it is originating in the lower airways and the movement or exercise acts as a stimulus to loosen it up. Where the cough is dry, it is more likely an irritated airway that is responding with a cough due to irritants being inhaled such as dust or even just forced air through the trachea or windpipe is enough to exacerbate the irritation.
COPD, IAD and Allergies in the Horse
Cases of inflammatory airway disease (IAD) are often seen as dry coughs and air movement through the trachea get these guys more irritated. Sometimes blood is coughed up, which reflects airway irritation but also dryness to the membranes in the windpipe. These cases are usually involving more the upper airway, including the trachea. In COPD, the airway problems are lower down or deeper, often combining airway narrowing with mucous accumulation. In reality, these cases can almost be seen as asthmatics to a degree as the conditions can be very similar. COPD horses can have a real difficult time moving air, dependent on the progression of the case, as the airways are narrowed thus reducing airflow and additionally, we have mucous that accumulates which also deters air movement. They are often coughing, but much deeper coughs, with evident phlegm or mucous production, a rattle in the throat and flared nostrils due to restricted airflow.
The diagnosis of respiratory allergies is very common, in my opinion, when in reality we are really dealing with an early stage COPD or even IAD horse. Respiratory allergies can impact the upper airway, including eyes and sinus cavities, resulting in eye discharge, mucous draining from the nose and a light cough. In reality, all three of these conditions are connected through the process of inflammation and immune dysfunction. Taking this into consideration, one condition can progress to another over time if not managed properly. Respiratory allergies can and do transform into cases of IAD and COPD over time. A large percentage of horses with IAD can and do present with clinical signs of COPD down the road in their career. It is all tied into inflammation and an improper immune response, the question is what stage you catch the condition.
Diagnosing COPD, IAD and Respiratory Allergies in the Horse
In regard to diagnostic tests, there are several and they do help us to differentiate exactly what condition we are dealing with, however, if you notice, the therapies are often very similar.
For diagnostic tests, we often will perform:
- A complete physical exam with full ausculation of airways with a rebreathing bag
- Bloodwork to rule out infection or other concurrent illness
- Upper airway endoscopy to evaluate the upper and lower airways
- Trans-tracheal wash to gain a sample of fluid from the upper airway for cytology and culture
- Brocho-alveolar lavage to gain a sample of fluid from the lower airways for cytology and culture
- Radiographs (x-rays) of the sinus cavities to rule out fluid accumulation or infection
- Allergy testing
Listening to the lungs and evaluating the patient at work is one key element. The horse does not breathe at a high rate, thus it is hard to get them to breathe faster or take a deep breath for us. In those cases, we will often place a bag or palpation sleeve over their nose to increase CO2 levels and force them to take a deep breath or two when remove it. We want a deep breath so that we can hear air movement in the airways, listening for distinct sounds or lack of sounds to help us determine the problem.
Endoscopic exams are helpful and allow us to rule out other major problems, while gaining a sample of fluid or even mucous for diagnostic purposes. In many of these cases, cytology or evaluation of cell types within that fluid return to us indicating a high presence of a type of white blood cell called the eosinophil, which is associated with allergic type of responses. In cases where there might be an infection, we often see higher counts of neutrophils, a type of white blood cell associated with infection. It is not uncommon, even in the case of early stage allergies, to have a secondary bacterial infection, so use of antibiotics is common to help clear this problem.
Treatment and Therapy Options for Respiratory Problems in the Horse
For therapies, there are several that are often employed traditionally:
- Antihistamines
- Corticosteroids
- Bronchodilators
- Allergy hypersensitization injections
These cases tend to be seasonal in nature, becoming worse during the Spring and Summer months. This is not only due to a higher load of allergens in the air and increased dust due to dry conditions, but is also the humidity that is present. Allergens obviously stimulate the immune response, which contributes to the inflammation and associated clinical signs. In those cases with more mucous production, the high humidity levels actually worsen the problem as humidity is moisture and adds to the already present mucous or phlegm that is present.
The therapies described above all target some aspect of the inflammatory or immune response, but more often than not, they are limited in their scope of action and may help one year, but not the next. It is not uncommon to start with antihistamines in an early stage condition, then the next year you are using corticosteroids. Many times, we note that with each passing year, the dose of corticosteroids needed increases and often, those same horses become dependent on the medication even during ‘off’ times of the year. We need to keep in mind that these medications do pose potential harm to the body with side effects that increase as dependence and dose go up. These side effects include immune compromise, laminitis and even organ compromise.
If we want to help manage these problems more readily, we need to see them for what they are and address it properly, and realize that they can and do progress from one to the other. The connector between all of them is the presence of an uncontrolled or excessive inflammatory response in addition to immune dysfunction. The immune response is actually hyper-active, reacting to almost every thing when it really shouldn’t. When the immune response gets hyped up like this, the production of inflammatory proteins likewise increases, which then contributes to a host of other problems. It is a viscious cycle.
The immune response is tied back to the gut in all species, as this is ‘home base’. In the majority of theses horses, the origin of the inflammatory and immune response is in the gut. By using the therapies mentioned above, we are doing nothing to address this problem, thus the problems persist and over time, the conditions become worse. If we address the gut, by reducing inflammation in that region and supporting the immune response, the results can be much better, often in a short period of time. Many of these patients improve and become less dependent on their prior therapies, which reduces potential for side effects, but overall, the approach makes them a healthier horse.
In all of these patients, we need to keep in mind progression of the condition as with a higher level of progression, the more tissue damage that is done which cannot be reversed no matter the chosen therapy. This is especially true of COPD cases, where scar tissue can accumulate in the lungs and impair air movement. The earlier we catch the problem, the better. This is not saying results cannot be achieved in an advanced case, but there, the results may be limited. Thus, if we have a horse with a mild cough, being diagnosed as just ‘allergies’, we need to manage this the same as if it were a case of COPD, as our goal is to control it earlier not later.
The patients that present to us are of varying degrees of clinical problems. In all cases, we will supplement with the Cur-OST EQ Total Support formula and combining it with the Cur-OST EQ Immune & Repair. This approach helps us to promote a healthier inflammatory response, balance the immune response and provide nutrients to aid in repair of the underlying gut problem. The response can be dramatic in some cases, while in others, it can take time due to progression of the condition. The key point here is we are not really addressing the main problem, but more targeting the imbalance within the body that is contributing to the effects.
In many cases, we will evaluate diet and other supplements that are ongoing in these patients. The concept here is that in many cases, preservatives and additives can contribute the gut problem and we want to improve the situation as much as possible to enhance overall health. An overall discussion of COPD in horses can be viewed in our COPD article. For review of diet, gut health and interaction, I recommend reviewing our recent research article and follow up article.
I hope this information helps to answer some questions and provide guidance.
All my best,
Tom Schell, D.V.M.
Nouvelle Research, Inc.
(images courtesy of Google Images)