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  Discussion on Mare born with partial paralysis of her esophagus
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Posted on Saturday, Jan 12, 2002 - 7:05 pm:

I have a coming five year old QH mare, born with no mobility in a percentage of her esophagus. As a foal, the University was able to diagnose this by putting an internal camera down her throat. Also rapid fire exrays showed a shot of milk entering her lungs each time she swallowed. in the computer banks linking these Universitys where vets train to become vets, none of these foals born with this rare condition had ever survived to see their second birthday.
She has survived and no one would know she had a problem, except if she gets ripping out in the pasture for a run of approx. a mile or more. Then she has trouble breathing and makes a loud, roaring noise until her respiration returns to normal, from the damage to her lungs as a foal when nursing her dam. She does not have heaves. She is never stalled, and runs on pasture year round, with timothy/brome grass hay free choice in the winter. No dust, no mold, no weeds in hay.
Last year, I bred her for the first time. Then, just five months into the pregancy, while still on her usual pasture, no hay, she suddenly began to struggle to breath, almost like an extreme advanced case of heaves, no cough or nasal discharge though. She miscarried the fetus, while standing, struggling to breath. In 24 hours, she recovered on her own and was back to normal. Now, last week, in the dead of winter, but now on hay (the same hay she has been on for 3 plus months, she began to struggle to breath, the same as the time in early Sept. when she slipped the foal. Although it is the same as a horse with advanced heaves, expiration extremely laboured, there is no cough, no nasal discharge. She remained on her feet, no choke, no signs of an allergic reactions, etc. She recovered in less than 24 hours. So it has happened twice, both times being kept outdoors, once in good weather on good grass pasture, once on very good hay, cut and baled at the right stage of maturity, basically dust free, no molds, no weeds. Regular deworming, shots up to date, and all other 20 horses are fine. Also, this is a closed herd, no access to strange horses, no chance of having contacted a contagious respitory disease. So what caused these two episodes and what are they? Please, I have had several horses come and go over 40 years with heaves, this is not heaves. The attending vets, say she does not have heaves.

Posted on Saturday, Jan 12, 2002 - 10:41 pm:

Hello Gayle,
Without examining the horse I cannot pretend to know what is wrong but the historys do suggest some possiblilities.

It sounds like there are at least two things going on. The first is the persistant problem of exercise intolerence. I suspect she had permanant damage from the early episodes of aspiration pneumonia documented with the esophagrams. This is probably not reversible and may be progressive. Important to understand is that changes in the lungs would not heard as a roaring sound so perhaps there is also some degree of problems with the tissues of the upper respiratory tract, see Equine Diseases: Respiratory System: Respiratory Noise in Exercising Horses for more on this.

The acute episodes have several possibilities and they may not even be related, but if we assume they are I think she aspirated some food resulting in a short lived broncho/pneumanitis. The mucociliary clearance mechanism begins to clean up the lungs, the inflammation and bronchospasim subside, allowing breathing to return to normal. The lack of cough does not let this out. I have seen aspiration pneumonias secondary to chokes that did not cough.

A second possiblity for the second episode needs to be considered: that pregnancy puts extra stress on the respiratory system and perhaps took the damaged lungs over the edge. Though you would think that in cases like this the respiratory distress would build slowly that is not always the case.

Have there been any other tests or exam findings performed? How about during the acute episodes what was the horses temperature and how did the lungs sound on auscultation? Were any treatments instituted for the acute episodes that seem to associated with the improvement?
DrO

Posted on Sunday, Jan 13, 2002 - 4:57 pm:

Dr.O,
During her short life, the mare has had just about every test possible performed on her, checking her lungs and respiratory system. As you can guess, she now can smell a vet a mile away and responds accordingly. Not to say vets smell bad, but they all seem to have that faint smell of disinfectants clinging to them. To answer your questions. Yes, aspiration pneumonia damaged her lungs. The tissue of her upper respiratory tract were damaged when a vet attempted to insert a stomach tube (which was not softened and made more pliable on a cold day) and it went astray.
Niether of these times were there any evidence of choke or a nasal discharge containing small particles of food, most often seen when a horse aspirates even a small amount of food. Her temperature was in the normal range, both times. Amazingly, lung sounds were as normal for her as posssible. As the closest equine hospital or large clinic is hours away, local vets were called that don't have a lot of equipment available to them. No treatment was instituted either time except for timely doses of Banomine to relieve pain and/or unknown inflamation.
I am well aware of and have seen, older mares with extremely advanced cases of heaves, poop their colts out the back door, but never at only five months (pratically to the day), along in their pregnancies. Always after the start of the ninth month of pregancy. I simply had hopes that you may have some idea, missed by other vets and myself for these two episodes. Once on grass pasture and once on grass hay. I might also point out that even when so sick as a nursing foal and her entire life, she has remained in good to excellent body condition and very active. Her breeding is the type where she never seem to not be running, bucking and playing. She actually is quite muscled up from free choice excersise. Gayle

Posted on Monday, Jan 14, 2002 - 8:10 am:

Hello Gayle,
I am not sure, but I think you misunderstand my point about the short term severe respiratory distress. I do not think she "choked" as the term means in horses (an esophageal obstruction): horse chokes have profuse nasal and oral discharges after the first few seconds.

What I think happened is the already demonstrated esophageal defect may have allowed the aspiration of a small amount of food into the lungs and the lungs responded with broncoconstriction.

The problem here may be that the horseman's term for choke is different than the human meaning. I use the example of choke in a horse above to demonstrate that I have observed the aspiration of food into the respiratory track without a cough. If you understood this great, I just wanted to be sure.
DrO

Posted on Sunday, Jan 20, 2002 - 9:23 pm:

Thankyou, Doctor. I did not misinterpret you. I can understand fully on dry feed matter, but grazing on grass and only grass, as in the first episode? And still no signs of any kind of nasal discharge? I am not talking "choke" here either. Should the lungs respond with (broncoconstriction) is there not some, any nasal discharge? From at least one of the nostrils? Even a clear discharge, anything? I phoned a friend at the University, handles only the severe equine cases, he said to print everything out and foreward to him, which I did. He said, there would have been some evidence of a nasal discharge. He says though, you have a good point, and perhaps it is to be considered. Does he know what is wrong with her, NO!!! Once again, I had only hoped for you to help me, and help me stop or correct this if possible. Gayle

Posted on Monday, Jan 21, 2002 - 5:50 am:

Hello B un,
No there is no nasal discharge with broncoconstriction and I am unsure why your doctor would think so. Human asthmatics are a excellent example of this. Many horses with acute onset of heavey episodes are suffering from bronchoconstrition without nasal discharge.

The problem is one of finding a "lesion" to account for all the facts: episodic, acute respiratory distress characterized by expiratory dyspnea that lasts for a short time and takes he other facts in your horses history into account. Only one lesion really seems likely and that is bronchoconstriction. I would be interested in hearing other theories.
DrO
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