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[nafex] Off-topic, sort of: tent caterpillars & equine abortions

Over in the central part of KY - in the Bluegrass area, around Lexington, 
they've been experiencing an exponential increase in the number of late 
term abortions/stillbirths in mares, as well as a marked increase in early 
embryonic mortality.  Same thing's been noted in Ohio and West Virginia, 
but it didn't make the press like it did around Lexington, which touts 
itself as the 'Horse Capitol of the World".

Things started happening a week or two prior to the Kentucky Derby, and 
during the course of the investigation, the spokespersons at the Univ. of 
KY have been throwing out a number of possible(though sometimes not all 
that plausible) causes, ranging from endophytic fungi in the grass, nitrate 
fertilization of pastures last fall, mold growth/mycotoxin production in 
forage damaged by our early April freeze.

Now, they've settled in on tent caterpillars.
They were very prominent this spring, and as we all know, wild cherry 
(P.serotina in this area) is their preferred host plant.  The latest 'trial 
balloon' the UK-Gluck folks have thrown out is that the tent caterpillars 
ate the cherry leaves, concentrated the cyanide/cyanogenic compounds in 
their feces & body parts, and then the mares became poisoned by 
consuming/inhaling caterpillar feces or the caterpillars themselves.   This 
theory suggests that the mares themselves were not affected, but that 
cyanide levels were high enough to cause fetal/embryonic death.

I realize that the folks at UK were under immense pressure from the entire 
horse industry, but personally, I don't buy it, not for one 
minute.  They're gonna have to show me some pretty convincing evidence that 
there's any significant amount of HCN or any other cyanogenic compound in 
TC feces, and that these mares were gobbling up enough of it to induce 
abortion - and prove to me that there's a significant level of cyanide in 
fetal tissues.
Some of these cases occurred on farms where there were NO cherry trees, and 
while I've not spent a tremendous time in the horse country around 
Lexington, I would suspect that most cherries would have long ago been 
removed from the properties, due to the danger inherent in livestock 
consuming wilted leaves if/when trees blew over, or big limbs were broken out.
Cherry leaves are only a problem in the wilted state - I've seen cattle & 
horses consume fresh green leaves straight off the tree, and fallen, yellow 
leaves off the ground, with no problem whatsoever.

Well, anyway, if you'd care to look at any of the stuff pertaining to this 
theory, look here for several linked stories.

Louis L. "Lucky" Pittman, Jr., DVM
Veterinary Pathologist/Asst. Prof.
Murray St. Univ.-Breathitt Veterinary Ctr.
Hopkinsville, KY


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