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COPD

CHRONIC OBSTRUCTIVE PULMONARY DISEASE

Poor little guy. Whoever said ponies are easy keepers need to be booted.

Chronic obstructive pulmonary disease (COPD) is an equine lung disease similar to human asthma. The clinical signs of COPD are caused by an allergic response to the particles in hay dust. It is most often seen in older horses (greater than six years old) that are stabled during the winter months. COPD is rarely seen in warm, dry climates where horses are kept outside all year. Horses with COPD may exhibit clinical signs such as "heaving" to push air out of the lungs towards the end of exhalation, coughing, weight loss, and exercise intolerance.

Wheezes may be heard towards the end of exhalation when listening to the airways with a stethoscope. A mucopurulent nasal discharge (comHeave Lineposed of mucus and inflammatory cells) may be seen, especially after exercise. The abdominal muscles of COPD-afflicted horses may hypertrophy (enlarge) and form noticeable "heave lines." (See figure at right). Heaves does not appear to be breed or gender related. There is evidence, however, that it may be hereditary.

Hay contains microorganisms such as bacteria and fungi as well as tiny particles of feed grains, plants, feces, dander, and pollen. These tiny particles become aerosolized in hay dust and elicit an allergic response when they are inhaled by COPD horses. While it is believed that the hypersensitivity reaction seen in COPD horses is in response to many different allergens, the primary microorganisms involved in the etiology of heaves are Aspergillus fumigatus, Thermoactinomyces vulgaris, and Faenia rectivirgula. Aspergillus fumigatus is a mold that grows on dead and decaying matter such as poorly cured hay. It is thermophilic ("heat-loving") and can thrive in the high temperatures achieved in decomposing vegetation. A. fumigatus forms spores which become airborne and can be inhaled. These spores are antigenic (they are recognized as "foreign" by the immune system and provoke an immune response) and allergenic. Both Thermoactinomyces vulgaris and Faenia rectivirgula are bacteria which produce spores that become airborne and can be inhaled. All three of these species of microorganisms are numerous in moldy hay.

COPD is a disease that affects the air passages (trachea, bronchi, and bronchioles) through which air flows into the lungs. The air passages are lined with layers of cells which constitute the epithelium. Below the epithelium is a layer of connective tissue called the submucosa. The epithelium and submucosa together are called the mucosa. Smooth muscle surrounds the bronchi and bronchioles all the way to the level of  the alveoli (the air sacs in the lungs where gas exchange takes place). Contraction of the smooth muscle encircling the airways is known as bronchoconstriction or bronchospasm.

The airways are equipped with natural defense mechanisms to eliminate inhaled particles. These mechanisms include coughing, mucus secretion and removal, and bronchoconstriction. Chronic obstructive pulmonary disease is a delayed hypersensitivity reaction to inhaled allergens (materials that provoke allergic reactions). The natural defense mechanisms in the airways of COPD horses are hyperreactive and, therefore, they overreact when foreign particles are inhaled. Inflammation is also one of the defense mechanisms of the airways but in COPD inflammation occurs in excess and its purpose is not clear.

Four to six hours after a COPD horse is exposed to hay dust, the airways become inflamed and massive numbers of neutrophils accumulate within the air passages. Neutrophils are specialized white blood cells that kill bacteria. In COPD, it is still unclear what role the neutrophils play. It is known, however that the substances normally used by neutrophils to kill bacteria are capable of causing some of the changes in the airway epithelium observed in COPD horses.

Each time a COPD horse is exposed to hay dust, its airways become acutely inflamed which causes the airways to become edematous (an abnormal accumulation of fluid in intercellular spaces). Repeated episodes of inflammation can cause the airway mucosal cells to proliferate.  Both edema and proliferation of the mucosal cells thicken the airway walls and obstruct normal air flow during breathing.

So, what does this all mean?

In equine COPD, inhalation of airborne allergens leads to airway inflammation which gives rise to bronchospasm.  Treatment therefore involves prevention of exposure to allergens by environmental management, reduction of inflammation by use of corticosteroids, and relief of airway obstruction by use of bronchodilator drugs.  Depending on the severity of the disease, use of the horse, and facilities available, one or all of these treatments may be used for a COPD-affected horse.   There is no cure for COPD and, therefore, treatments need to be continued for life.

The simplest way to treat a COPD horse is to change the environment so as to minimize exposure to hay dusts. This can easily be accomplished by putting the horse out to pasture. COPD-afflicted horses put out to pasture will go into clinical remission. If a horse must be stabled, then it is necessary to eliminate the use of straw for bedding and hay for feed. Even though the dust levels in the barn may seem insignificant, research has shown that the dust levels in the breathing zone (i.e. around the nose) of a horse eating hay can be as much as thirty to forty times higher than in the rest of the stall. When a horse is eating a low dust feed such as pellets, the dust levels in the breathing zone are equivalent to those in the stall. An effective management strategy for stabled COPD-afflicted horses, therefore, is to bed them on shavings and feed them a low dust diet. Feeds low in dust include complete pelleted feed, alfalfa cubes, and grass silage (haylage). Horses in adjacent stalls preferably should be kept in the same manner so as to prevent hay dusts from contaminating the stall of the COPD horse. However, if this is not possible, simply changing the management in one stall can dramatically improve lung function in a COPD-affected horse.

Hay should not be stored near the stall of a horse with COPD. Improving the ventilation in the barn can also help to minimize airborne particles. This may be accomplished by merely keeping the windows and doors open whenever possible or by using more sophisticated ventilation systems.

It is very important to realize that very short exposure of a COPD-susceptible horse to hay dusts can initiate inflammation and airway obstruction that can last for days.  

So, what can you do?!?

When Tonka started showing signs of COPD, ie heaves, the vet was the first person consulted. We placed the little guy on Dexamethozone treatment, and changed the bedding material from straw to white chips.

After the treatment phase ran it's course, his condition was starting to worsen, and he started developing the heave lines.

Due to no grazing area, and not wanting to go to a fully pelleted feed (horses need plenty of roughage for their digestive system), I addressed the grass.

A few months prior, ever since his founder (didn't I say ponies are not real easy keepers?), I changed the source of hay, to a local farm. The hay helps keep his founder in check, however, his COPD started.

Since COPD is due to airborne particles that are causing reactions in the respitory system, I addressed a method to reduce the airborne particulates.

Hence, I designed, and built the....

Hay Soaker!!!

Soaking the hay, is a laborous task. Knowing that I was going to be doing it for a LONG time, I had to devise a method to make it easy. Since holding hay under water is akin to trying to hold a beach ball under water, both holding down, and extraction was needed to be implemented in the design.

With all the steel stock that I had laying around, I pulled out the MIG and chop saw (oh yea, lets throw some sparks!).

I started off with a three foot stock tank. The size of the tank needs to be larger that the amount of hay that you are going to be soaking. Also, bear in mind that you will need a drain plug in whatever you use. Trust me, you will be wanting to drain the water about every three days of making tea.

Next, I stopped by the outdoor store, and picked up a boat trailer wench. That with a good length of 3/32 aircraft cabling, a few pullies, and two BBQ grills, I headed home to start the construction.

I framed the top of the stock tank with 1 1/2"x 3/32" angle iron. I placed two top bars of 1/2"x3/32" angle lateraly across the top of the tank. I extended the frame off on the left side to tack the boat wench to the framework. Using the lateral brackets, I attatched 4 S hooks to attatch the downward pullies. On the frame, on the front side at the base of either lateral, I placed three more S hooks, and double pullies.

The extraction assembly is constructed out of 1/4" bar stock, with a few 1/2"x3/32" pieces welded to help keep it together. The aircraft cabling is routed from the wench, through the double pullies, to the single, the it wraps around one point of the extraction assembly.

The soaking assembly is two BBQ grills, that are tack welded 90 degrees to each other. I then welded 4 pieces of 1/4" bar stock between it and a length of 1/2"x3/32" angle at a right angle. Using two more pieces of 1 1/2"x3/32" angle, I tacked at either end of the top bar to give it something to hold steady.

Makes sence?

No, I didn't think so. I'm not that good at describing a design.

Lets see if the pics help.

Here is a top view with the water drained. You can see the extraction assembly, and how the aircraft cable is routed. There are four individual lengths of cable, all attatched to the wench hub. The three double pullies help keep the pair of cables together to the single pullies that drop the cable down.

Here is an image to show the extension for the boat wench, and the hold down assembly. This is how I leave the soaker when not in use. Notice on the top bar of the assembly, there is a small length of angle iron tacked to either end. These are to give the assembly something to hold on to, and due to their 4" length on top, also helps preventing the holding assembly from rotating while it is holding down the hay.

Here is another look at the soaker, and the water level I try to maintain in it. Also, notice the color of the water. Believe it or not, this is only after two uses. Like I stated, you will be making tea every time you use it.

Anyhew, when the extraction assembly is fully raised, you will want about 4" of clearence between the assembly and the top level of the water. No good draining if the hay doesn't fully get out, no?

Here is an example of the soaker doin it's job. The extraction assembly is fully lowered, then the hay is placed in the tank. Using the hold down assembly, the hay is fully pushed under the water, then the angle iron on the outer ends of the top bar is placed into the angle iron the pullies are attatched to. If the frame was built tightly on the stock tank when it was empty, the pressure of the water in the tank will help hold the frame in place when being used.

Twelve cranks on the boat wench later, the hay is up out of the water to drain.

Points to ponder........

There are several different sources that state soak times from an hour to 24 hours. What a dung fork full......

What you are attempting to do with soaking the hay, is to knock down the airborne particles, not make hay mush. However, there is something to be stated about soaking to help knock down the carbohydrate and potassium levels in the hay. If you are attempting to do that, there is a good article at Safer Grass that you may want to view.

Anyhew, for COPD this can be used to give you an idea. I soak the hay for about 5 minutes, or until the big air bubbles are done coming up. You want to get everything wet. It only takes a few minutes to accomplish that. Then I let the hay drain for about 10-15 minutes.

The hay will be a bit heavy, and you will get a bit wet when you haul to the stable. Also, beware of the hot wire. Wet hay does conduct electricity, and it is a rather shocking experience. (hehe, get it? Yea, it was bad....)

Doing this for every feeding, had reduced Tonka's cough to non-existance. Since both Tonka and Bianka share the stable, I have to soak all the hay every feeding, and I soak at feeding time.

I missed soaking once, I had to have somebody feed the little ones for me due to my duty, and when I got home, he was coughing again. It only takes one unsoaked feeding to start the cycle over again, and it takes a few days to fully get the cough gone.

I have been doing this for the last few months, and I can say that I have discovered no problems, with the notible exception of having to unplug the hot wire every time (only takes me once to learn something like that.......) The little ones don't seem to have any complaints about eating the wet hay either.

I have a Durafork sitting by the soaker to help push down the extraction assembly (it doesn't weigh enough to go down unassisted), and to remove the left over grass after a soaking.

When it comes time to drain and clean the tank, I will crank up the extraction assembly, and place the holding assembly on it like it would be used, then crank the tension enough to hold the entire assembly together. I then use a prybar to lift the assembly off the tank. That way, I can drop the tank to the side and hose it out. That water does get really nasty after a few uses, so you will be doing this often. That is the reason I placed the soaker off to the side of the feedshed, away from the stable, by the hose. The hill it's placed on allows the water to drain away from everything.