Jan. 8, 2016 02:02

Horse Health-"Heaves" in Horses Pt 1

HORSE HEALTH“Heaves” in Horses

Part 1 of 2

Some horses suffer impaired respiratory function  due to congestion and constriction of the airways—similar to a person with asthma.  This condition is generally the result of breathing dust, mold particles or pollens that set up an allergic reaction, and is often due to the conditions in which we keep and feed our horses.

Horses are super athletes, primarily because they have good lung capacity for keeping the blood and muscles well supplied with oxygen during strenuous activity.  Anything that interferes with proper working of the lungs and air passages can limit a horse’s athletic ability. 

Bruce Connally, DVM (equine sports medicine practice in Berthoud, Colorado) says “heaves” was called COPD (chronic obstructive pulmonary disease) for a while, because people thought it was similar to “smoker’s lung” in humans.  “But now we’ve found that heaves is more like human asthma—in which the airways become constricted and it’s hard to breathe.  Whereas COPD involves permanent scarring (and can be the end stage of heaves after a horse has suffered from breathing problems for a number of years, with damaged lungs), the most common cases of heaves that we’re trying to treat are simply an airway constriction.”  If you can get the airways open again, the horse does fine.

“Heaves is most common in environments with lots of moisture and molds.  When I lived in Michigan (after growing up in arid Wyoming) we saw a lot of heaves in horses.  Dry air is healthier.  There is a much higher incidence of heaves in wet climates, but as more horses become indoor horses or spend a winter—or even the summer—in barns, heaves occurs frequently in a dry environment as well,” he says.

Some horses tend to develop breathing problems when eating certain kinds of hay.  They might cough when fed dusty alfalfa hay, for instance, and have fewer problems when fed grass hay.  This may be due to certain molds in the alfalfa.  “If a coughing horse is on alfalfa I recommend switching to grass, and if they are on grass hay I switch them to alfalfa.  This is because there are different molds in the different types of hay, and a horse might be sensitive to a particular type of mold,” he explains.

It’s like human allergies.  If a person has hay fever triggered by brome grass, then alfalfa generally wouldn’t bother them.  Allergies are often specific to certain plants.  Once you figure out what triggers your horse’s breathing problems you can try to avoid that, and have fewer incidents.  “Then you won’t have to give as much medication,” says Connally.

“Figuring it out, however, can be a real challenge.  Allergy testing can be helpful but doesn’t always work.  We can do skin tests or blood tests but these aren’t perfect tests and are controversial.  It is still a challenge to interpret some of those test results,” he explains.  A horse owner might spend a lot of time and money on testing and still not know what sets off the horse’s breathing problems.

sOften if you can just change the horse’s environment it will help.  If the horse lives in a barn, put that horse outdoors.  When I was in Michigan, Dr. Ed Robinson at Michigan State University had a group of horses he was doing research on.  As long as he had them out in a green pasture or outside, they didn’t have symptoms.  When he needed to do a research study he’d just bring them into a stall and bed them in straw, and within 3 days they would be huffing and puffing.”  The dust and poor ventilation in a barn often sets up a sensitive horse for an attack of heaves.

“We talk about dusty hay, but a lot of what we call dust is actually mold spores.  When you open a dusty bale and it puffs up a cloud of particles, it isn’t always dust; it is sometimes mold,” he says.  There may be mold riding on those tiny hay particles that float on the air.

“One of the treatments for heaves is to wet down the hay to settle the dust,” says Connally.  If the horse is outdoors where there is plenty of air movement (and not in an enclosed, poorly ventilated barn, you can shake up every flake of hay to get rid of most of the dust and then sprinkle the hay to settle the rest.  You don’t want to shake up hay in a barn, however, or it will simply put more dust particles into the air for horses to breathe.

For a serious problem, soaking the hay works better than sprinkling.  “If you can wet the hay enough to get the mold spores stuck to the hay instead of floating around in the air, the horse does fine.  It doesn’t hurt him to eat those spores, as long as he doesn’t inhale any of them while he is eating,” Connally explains.

“Soaking works best, but it’s messy, and challenging to do in freezing weather.  It’s best if you can get that horse out of the barn into an outdoor pen.  Don’t bed him in straw; try some other bedding that’s not as dusty.  Sometimes wood chips are not as dusty, and there may be different types of mold in wood than in straw.  For a horse that has a really bad time eating hay you can switch to hay cubes.  I don’t like feeding hay cubes because there is risk for choke and colic, but it does get rid of a lot of the dust,” he says.  Simply putting the horse outdoors won’t solve the problem if hay is fed in a big bale where the horse is burying his head into the bale, breathing dust. 

Steaming the hay works better than soaking.  There are some commercial steamers available that do a good job of steaming (which thoroughly wets the hay but doesn’t leave a dripping mess like soaking).  Use of a steamer can enable the horse to continue to eat hay with no ill effects.

SIGNS OF HEAVES – The most well-known signs are coughing and wheezing, especially when eating hay or exerting.  “Milder symptoms include a slowdown in performance.  For instance, the barrel horse may run the barrels a half second or a second slower, and a rope horse doesn’t catch his calf as fast.”  The horse doesn’t have optimum wind capacity to run his fastest speed.

“Many timed events are in an indoor arena—and those are dusty.  They really fire up my asthma!  The horse may cough a little, but the biggest clue is that he just doesn’t run quite as fast.  That’s probably the mildest symptom we see.  I use barrel racing or roping as examples because they are so competitive that even a half second slower is a huge amount and makes the difference of winning or not.  Anything that affects that horse’s speed really shows up in how you place,” says Connally.

More obvious signs are constant coughing, and labored breathing, trying to push the air out of the lungs through restricted airways.  Horses that have had heaves for very long develop a characteristic “heave line” along the lower abdomen—a ridge of muscle that has become thicker due to the extra exertion required to breathe.

Drawing the air into the lungs is hard, but breathing out is harder, taking an extra push with the abdominal muscles.  This is a simple way to tell the difference between heaves and pneumonia; the horse with pneumonia has trouble drawing air into his lungs and the horse with heaves has trouble pushing the air out.

With chronic, long-standing cases, horses get to where they are breathing so hard that they lose weight.  They can’t hold body condition because they are putting so much effort into breathing.  They also may not eat as much as they should, because they are spending their time and effort trying to breathe instead of eating.

“This is similar to a person with end-stage lung disease from smoking.  These people are often very thin because it takes so much effort to breathe.  I occasionally see horses at this stage.  You can’t ‘fix’ those, and often you can’t even maintain them; they are near the end of the line,” Connally says.

Thus it is important to recognize signs early and try to change the horse’s lifestyle and environment so he never gets to that point.  “The environment is so important, but many owners want to simply try a drug because it’s easier.  It might be costly, but often that’s what people want to try.  The drugs are useful, but environmental changes are critical.”

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