If you’ve been hearing your horse cough in his stall, you may have concluded that it was dust making him cough. You may not have realized how very serious this can be. Even though mold, pollen, dust and other allergens can make people cough without serious repercussions, the fact is when horses have this response to allergens, the end result may be a serious and chronic respiratory problem known as heaves.
In this article, we discuss this condition and provide sound advice to help you prevent and deal with it. Read on to learn more about heaves in horses.
What You'll Learn Today
What Is Heaves?
In the past, we thought that heaves was very similar to chronic obstructive pulmonary disease (COPD) in humans. Now we know that this isn’t true. COPD is typically the result of excessive cigarette smoking or extreme exposure to other irritants over a long period of time.
This exposure to potentially toxic substances causes inflammation and damage of the airways, along with excessive production of mucus which blocks the airways. COPD causes heavy scarring which is irreversible.
If you want to compare heaves to a human condition, asthma is closer. This is not a perfect match, but it’s a better comparison. Asthma is an allergic airway disease. Heaves is a response to an allergen, but it is not an allergic response and does not indicate a disease condition in the horse.
Heaves is most like occupational asthma which is experienced by people who work in circumstances where there constantly breathing dust or other allergens. These irritate the lining of the airways and the interstitial lung tissue causing an inflammatory reaction. If caught in time and dealt with, this does not cause scarring and can be reversed.
Is Heaves Hereditary?
Heaves does seem to run in equine families, but researchers are unsure exactly why this is. Research does indicate that if a horse has one parent who has experienced heaves, that horse is more likely to develop this respiratory condition. If both of a horses parents have had heaves, the chances that the offspring will develop the condition are quite high.
What Happens When A Horse Has Heaves?
When a horse is excessively exposed to an irritant such as dust, mold or pollen over a long period of time, the mucosal lining of the lungs becomes inflamed. This triggers the immune system and causes white blood cells to enter the lungs to fight the inflammation.
Unfortunately, this triggers excessive mucus production, which in turn constricts the bronchial tubes and plugs the airways. The immune system response can also cause airway walls to go into spasm, causing thickening of those walls. This makes it that much more difficult for the horse to breathe.
Very early signs of heaves may include a compromise of performance. For example a barrel racer may begin running just a few seconds slower than before. If caught in these early stages and treated right away, heaves can be very successfully dealt with.
A horse with heaves may cough constantly and breathe in a labored manner, especially upon exhalation. The affected horse may wheeze as he moves about during the day and especially when attempting to eat hay or when being ridden.
Why Is It Harder For Horses With Heaves To Exhale Than To Inhale?
It is hard for a horse to draw in air when his lungs and airways are constricted, but it is even harder to push carbon dioxide back out again. It takes quite a bit of force from the animal’s abdominal muscles to empty the lungs.
As a result, horses who have had heaves for quite a while develop a line of muscle on the lower abdomen. This ridge is called a heaves line, and it is developed when the horse exerts itself mightily in order to breathe.
This state of affairs can cause a horse to fail to thrive. In fact, horses suffering from chronic heaves may lose condition at a rapid and alarming rate. They may become extremely thin. When a horse reaches this point, it may not be possible to facilitate recovery.
What Causes Heaves?
Sometimes, heaves can be seasonal. For example some horses may begin to show symptoms during hot, humid times of year. This is especially common in the southeastern United States.
When the weather is hot and humid and there’s a lot of pollen and mold in the air, it’s very easy for a horse to develop heaves. When this happens, it’s good to bring the horse indoors away from heat, humidity, pollen and air contaminants.
Take care to provide fresh, clean, low dust bedding and to maintain good air circulation in the barn or stable while the horse is indoors.
What Can You Do To Prevent Or Treat Heaves?
Good daily practices go far toward preventing the development of heaves. Most of the time horses develop heaves when they are kept in a dusty barn and fed dry hay. Conversely, horses who live outdoors and eat fresh grass seldom develop heaves.
If your horse is showing signs of heaves and does stay indoors quite a bit, a change of venue may be all that’s necessary to facilitate recovery. Even horses suffering from very severe heaves may recover significantly or completely by simply living outdoors in the fresh air and eating fresh grass instead of dry, dusty hay.
If you don’t have access to good pasture, you should strive to keep dust, mold and pollen levels low. Soak your horse’s hay for a few minutes before you feed it. This can help wash off some dust, pollen and mold spores.
Keep your horse’s stall clean and dust free, and be sure to do your cleaning while he is outside. Don’t clean the stall with the horse in it as cleaning stirs up dust and can cause problems.
It’s a good idea to turn your horse out for a couple of hours while the stall is being cleaned. Don’t let him back in until the dust has had a chance to settle.
Use dust free bedding, such as wood chips or shavings, instead of straw. Straw is full of dust and is a major offender in terms of causing heaves.
Additionally, it’s a good idea to spray down the surfaces in your horse’s stall with a simple spray bottle several times a day to keep the dust from flying. This also serves the purpose of adding a little moisture to the air.
What Can Your Vet Do For Heaves?
For chronic cases that can’t be treated any other way, your vet may recommend using systemic steroids. These may be administered as an oral medication or by using a nebulizer or inhaler.
It’s important to understand that steroids should only be a stopgap measure. They should not be used on a permanent, ongoing basis. Excessive use of steroids can cause kidney and stomach problems. It may also trigger bouts of laminitis. This is especially true of horses suffering from Cushing’s disease or metabolic syndrome.
For these horses, a medication called Ventipulmin can be administered using a bronchodilator. This medication reduces smooth muscle contractions in the lungs and helps keep the airways open. It may also impart anti-inflammatory effects.
Just as with steroids, Ventipulmin should not be used on a chronic ongoing basis. Overuse causes the medication to stop being effective. It should only be used to get severe symptoms under control. The focus should be on correcting problems in the environment that are causing the horse to have heaves.
For more information refer to this Pdf document from Colorado State University.