Wowza!! It has been a hot one this weekend. Hopefully you all made it through the long weekend. Who am I kidding? Of course you made it through the weekend, you had to in order to read my blog this week.  Luckily, my staff knew just what a scorcher it was going to be and left me and Teeny in the lovely air-conditioned office for the weekend. I spent my weekend getting caught up on my sleep and refreshing my memory about equine asthma.

Equine Asthma, COPD, Recurrent Airway Obstruction, Heaves, Inflammatory Airway Disease, which is it? Why can’t these humans pick a term and stick with it? Well, as I found out this weekend, there is a reason why it has so many different names. The current accepted term for equine airway disfunction is Equine Asthma. Subcategories of equine asthma include Inflammatory Airway Disease and Heaves/RAO. To break it down even further, Heaves/RAO can be divided into Pasture-associated and Barn-associated. So, how do we determine if your horse has Equine Asthma, and if they do, which form they have? That’s where my docs and I come in. I’m going to give you a brief overview of the different forms of Equine Asthma and if you have a concern about one of your horses, you’re going to call the clinic and schedule an appointment with one of my docs.

Inflammatory Airway Disease

IAD is a respiratory disease that typically affects younger horses. It is characterized by a lingering cough, poor performance, increased breathing efforts, and prolonged recovery after exercise. Some horses may have watery-to-white nasal discharge but will never develop a fever. What sets these horses apart from horses with Heaves is that they are normal at rest with no increased respiratory effort or rate. Their appetite and attitude remain unchanged at rest.

What do you do if you notice your horse showing any of these symptoms? First, you call my clinic and my docs will come out and perform a thorough physical examination. This may include a rebreathing exam where they place a bag over your horse’s nose and mouth. While your horse is staring at you like, “what the heck are they doing to me, mom?” my docs will be listening closely to your horse breathe. Once the bag is removed, they will continue to listen while monitoring how long it takes your horse to breathe normally again, as well as note any change in lung sounds or coughing. Depending on what is seen and heard on the physical exam, my docs may recommend you bring your horse to the clinic for further diagnostics.

When you bring your horse to the clinic there are a couple diagnostic tests we will perform. First, my docs will perform a Bronchoalveolar Lavage (BAL) where they will obtain samples from your horse’s airway to send to the lab and look for inflammatory cells. They will also perform an endoscope exam to the upper airway. A small camera is passed up your horse’s nose and into their trachea where they will look for excessive mucous buildup.  I sure hope my docs don’t ever try and stick anything up my nose. I can’t promise I won’t scratch anyone if they do!

Based on the diagnostic results, my docs will recommend certain treatments, including environmental changes. The goal of environmental changes is to reduce dust allergens. This can be accomplished by soaking hay and grain, and bedding horses on paper or wood shavings. Your horse should be out of the barn during cleaning and remain out for an hour after chores are complete. This will prevent them from breathing in excessive dust particles that may be floating about after cleaning is complete.

My docs may also recommend a course of systemic steroids to reduce inflammation in the airways. It has been shown that Omega-3 fatty acids help to reduce inflammation as well. I’m not convinced that horses will readily eat fish oil, but it sure sounds delicious to me! There are commercially-developed Omega-3 fatty acids that are more palatable to horses than straight fish oil. My docs may also recommend bronchodilators such as clenbuterol or albuterol which may come in oral or inhaled forms.

Luckily, if your horse is diagnosed with IAD, the prognosis of a full recovery if treated is excellent. If cats got IAD, I would just take it as my sign that I should never exercise again. Oh wait, I don’t currently exercise. I guess we will never know if cats get IAD.

Heaves/Recurrent Airway Obstruction

Unlike IAD, a horse with Heaves/RAO is not normal at rest. You may notice your horse breathing rapidly or with more effort. You may even hear them coughing more frequently. You may also notice nasal discharge along with exercise intolerance. Horses with Heaves will have the classic “heave line” at the bottom of their ribs due to increase in abdominal muscle mass from excess work performed in order to breathe. Some horses with Heaves may become in appetent, although why horses decide to stop eating is beyond me. The horses usually experience weight loss due to decreased feed intake. Similar to IAD, horses with Heaves will not typically have a fever.

You may recall I mentioned early on that there are two different types of Heaves, Barn-associated and Pasture-associated. Horses with Barn-associated Heaves spend the majority of their time kept in a stall where they are exposed to typical molds, dust and endotoxins in hay and straw. Horses with Pasture-associated Heaves typically reside in the Southeast and spend the majority of their time on pasture where they are exposed to inhaled allergens. Both types of Heaves result in lower airway inflammation, but exact factors causing the airway dysfunction is unknown.

Heaves is diagnosed by BAL and endoscopic examination. Radiographs and thoracic ultrasound are also useful diagnostic tools used to further characterize the inflammation in your horse’s lungs.

Treatment for heaves is similar to that of IAD. At the forefront of treatment is to reduce allergens by soaking hay and grain. It is also important to keep horses with heaves off of round bales as they are very high in endotoxic and organic dust. Horses with Barn-associated Heaves should be kept on pasture and horses with Pasture-associated Heaves should be kept stalled except in the winter months when allergens are low. Systemic steroids and bronchodilators are also recommended for horses with Heaves.

Now that you are an expert on Equine Asthma, if you are concerned that your horse may be showing any of these signs, be sure to contact me at the clinic and I will get you in touch with one of my docs.  We will get out to check on your horse as soon as possible.

Now it’s time for me to go back to enjoying the remainder of this holiday weekend in the cool AC. Take a moment to remember all those who have served our country and provided us with the freedom to nap all day.

Until next week,

~Tony