Michael -- In domestic horses, we associate the same kind of eroded band
-- that occurs primarily around the buccal side of the teeth, just at the
gum line, and which may also extend around the anterior "prow" of the
second premolars -- with sugar in the diet. "Sugar" means (1) high simple
carbohydrates or carbohydrate concentrates, i.e. grain, especially rolled
or cracked oats; (2) high fructan grasses; (3) molasses; (4) refined
sugar, i.e. excessive amounts of "sugar cubes" fed as hand-treats. In the
developed countries, my survey shows that skulls collected
post about 1980 are very likely to have this kind of damage to their
teeth, and it is associated mostly with the advent of bagged, processed
"sweet feed" and "senior feed" that the leading companies lace with heavy
amounts of molasses -- not for any benefit to the horses, but so that the
customer may be able to detect how "good" the bag smells from clear
across the store. Unless bagged horse feed smells like childrens' breakfast
cereal,
you see, it doesn't sell as well. By contrast, I can also tell you that in
my entire professional life, I have seen (count 'em) TWO individual teeth
from fossil equines that had any evidence whatsoever of caries.
Now, your skull of course comes from an animal that died a long time
before the advent of bagged sweet-feed. There are thus several of the other
items in the above list to consider. If you can talk to your colleague who
does the paleobotany from the site, she or he may be able to check off one
or more of the following possibilities: (1) Cool-season grasses, those
with C3 metabolisms, can concentrate large amounts of fructan in the
spring and also when being grown on irrigated pasture. (For great info about
this,
please go visit Katie Watts' website at www.safergrasses.org and order some
of her
powerpoint disks). The genera I would
look most closely at are Schedonorus and Bromus, but there are many more
choices and your paleobotanist will be able to help you there. (2) Sorghum
bicolor in any form, whether grain sorghum (Milo) or sweet sorghum (used
to produce molasses); or the very closely related Johnsongrass (S.
halepense). These are not only super-sweet grasses but they'll poison the
animal by their content of cyanogenic glycosides, which upon being chewed
or crushed are converted to prussic acid. Surely the ancients had to
learn about this the hard way, and maybe that's why you have a skull. (3)
Grain feeding as I said, especially of oats; but in ancient times I
believe Barley (Hordeum, sometimes called Critesion) was more common. Here
you can look at my Vindolanda report with all the photos from several
years ago -- I had nice evidence of the use of a cheap millstone via
scratches on the teeth -- there was a lot of grit in the grain they were
feeding their animals. Remember too that both wheat (Triticum) and oats
(Avena fatua or Avena sativa, or other Avenas) can be cut at the "dough"
stage or a little later -- in other words, after the grainheads are fully
emerged but the leaves are still green. When cut this way, the stuff is
made into a hay called "greenfeed", and it too is just loaded with fructan
and simple carbs that make for caries.
There is one other possibility too, although the teeth in your photo do
not look very problematic in this regard; but, again, you're not
presenting a full set and what goes in one part of a horse's mouth does
not necessarily go for other parts. But if you can look for
malocclusions, that's a likely cause. A horse chews primarily by an
upwards-and-oblique stroke, but if anything blocks the full extent of that
stroke -- such as "points" but also missing incisors or maloccluding
incisors -- then the jaw does not travel its full lateral extent. When the
jaw does not travel through its full excursion, the cheek tissues are not
pulled tight and food material that's in the buccal pouch does not get
squished out. This is the only means an equine has of "cleaning" the
buccal side of its cheek tooth row, as they cannot put their tongue in
their cheek (or their finger in their mouth) as we can.
As an aside, folks, on that grass thing: I'm just about to publish a major
book-on-disk entitled "Poison Plants in the Pasture: A Horse Owner's Guide,"
tightly focused on broadleafs as well as grasses and other monocots that
have a track record of being problematic. Unlike other manuals, there is no
techno-speak, so here's a sweet way to overcome what one reviewer called
"fear of grasses" -- there are about 65 of the commonest ones in there, and
I promise that looking at the book will cause you to learn them. Where most
manuals give you one "diagnostic" field photo, the reason this book is over
1,000 pages long is that I give you two to ten pages of photos for each
plant that clearly show the diagnostic characters -- I did this because I
was tired of tearing my hair out trying to figure out what plant I had. Now
I know my own pasture intimately, and I also know how ignorant about this I
really was through many years of horse ownership. But this book may be of
use to you-all as well, just to give you a leg up on the botanical side of
your knowledge. The price will be about $50USD and the PayPal button will be
up in the "bookstore" section of our Institute website at
www.equinestudies.org.
Happy hunting --
Deb Bennett, Ph.D., Director
Equine Studies Institute
Livingston, California
-----Original Message-----
From: Analysis of animal remains from archaeological sites
[mailto:[log in to unmask]]On Behalf Of Michael MacKinnon
Sent: Thursday, January 31, 2008 9:27 AM
To: [log in to unmask]
Subject: [ZOOARCH] equid dental pathology
The following link displays a uniform groove across the buccal edge of some
donkey teeth, from a late-antique site in southern Italy. Any thoughts?
http://www.alexandriaarchive.org/icaz/icazForum/viewtopic.php?t=926
I suspect it has something to do with calculus deposition along the gum line
(the mandible has not survived in this case - well it's in hundreds of
scrappy, tiny pieces), which has aggravated some caries to erode away part
of the tooth. The line extends around both the buccal and lingual edges.
Still, the line had be thinking about enamel hypoplasia in equids (although
the uniform nature of the line here rules that out for this case). Does
anyone know of cases of enamel hypoplasia in equids, or is the situation
much like in bovids where this condition is difficult to see macroscopically
because of the cementum layer covering the tooth (not to mention calculus
depostion which can also obscure things - and calculus seems to be common
among many bovids - at least most of the ones I've seen from Greek and Roman
sites around the Mediterranean).
Thanks
Michael MacKinnon
--------------------------------------------
Dr. Michael MacKinnon
Department of Anthropology
University of Winnipeg
515 Portage Avenue
Winnipeg, Manitoba R3B 2E9
Canada
phone: (204) 786-9752
e-mail: [log in to unmask]
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