Dear Deb,
Many thanks for the detailed information on laminitis. This will be extremely useful for me when I write up the report.

/Lena

----- Original Message -----
From: [log in to unmask]
To: "Lena Strid" <[log in to unmask]>
Cc: [log in to unmask]
Sent: Monday, 13 December, 2010 9:14:45 PM
Subject: Re: [ZOOARCH] Pathological horse hoof

Dear Lena: The item you present is not the horse's hoof, but rather the
coffin bone. This is a common confusion. The "hoof" means the
keratinous, epidermal "capsule" which fits around the coffin bone. The
hoof capsule
is composed of the capsule itself plus the other epidermal parts, i.e.
the sole and frog, which together constitute the horny covering of the
distal part of the limb.

As you probably know, each part of the epidermal capsule is secreted by
an underlying dermal or "live" ("sensitive") so-called corium, so that
the capsule itself is secreted by the cells of the coronary corium
(located in
the coronary band, supported by the coronary groove); the frog by the
frog corium; the sole by sole corium.

The dermal "sensitive" and epidermal "insensitive" components of the
frog and sole are held together -- in other words, the frog and sole are
held on -- by thousnds of tiny papillae which protrude from the dermal
layer and are received in sockets of the epidermal layer.

By contrast, the dermal and epidermal capsule (i.e. toe, pillars,
quarters, buttresses and bars) interdigitate via laminae. The laminae of
the dermal layer are the modified periosteum of the coffin bone (some
books will tell you that "the coffin bone has no periosteum"; I have
even heard veterinarians say this. It's a good example of confusion
induced by
terminology, possible only when the speaker has no knowledge of the
relevant embryology). The interdigitation is like two pleated curtains
hanging side by side; the pleats are oriented parallel to the outer
surface of the coffin bone. The interdigitation, which may involve
primary, secondary, or tertiary folding, is not in itself sufficient to
anchor the horny capsule; anchoring is provided by microscopic dots of
short collagen fibers which act as "rivets" that attach the opposing
dermal and epidermal sheets.

If the pleating which constitutes the interdigitation of the sensitive
and insensitive laminae of the hoof were to be stretched out or expanded
so that it lay flat, it is estimated that in a full-sized horse that
wears a
no. 2 shoe there would be 8 square feet of effective attachment surface.
This is also a measure of the richness of the circulatory supply, for
each finely-divided pleat of the sensitive laminae carries a small
artery and
vein, which within that pleat ramify to ensure an abundant supply of
oxygen and nutrients to the cells which maintain and produce the
epidermal daughter cells.

Likewise, each papilla which reaches out from the corium of the sole or
frog carries an incredibly rich blood supply.

Further, there is at the distal rim of the normal coffin bone a
circumflex artery, which receives supply via foraminae normally
developed in the
coffin bone, and which ramifies just behind the edge to supply the area
of the distal hoof capsule and the outer edge of the sole, i.e. the area
that would normally lie just internal to a horse shoe.

This much anatomical information having been given, it is only necessary
to say of your specimen that it represents a fairly typical case showing
three phenomena. The first two reflect the remodeling of the bone
because in life the hoof capsule was allowed to become unbalanced
medio-laterally; this is what accounts for the fact that the specimen
has greater
medio-lateral asymmetry than normal. The second change is the flattening
of the bone by lowering of the angles of the wall and toe, and the
forward shift of the posterolateral corners of the bone; these are due
to the hoof
capsule having been allowed to get out of antero-posterior balance,
something referred to by modern horsemen as 'run under heels' or
sometimes 'sand heels'.

The third change is a degree of necrotic destruction involving the
distal 1/3 of the bone, especially at the toe. The disease that usually
causes this in modern horses is called 'founder' and the cascade of
sequelae that
affect the hoof are called 'laminitis'. In the laminitic horse, the
disease process causes the destruction of the collagen rivets that hold
the laminae together, and as a result, the coffin bone sinks and rotates
within the horny capsule. It may rotate either mediolaterally or
anteroposteriorly, i.e. the coffin bone will get to where it is tipping
toward one side, and it normally sinks so as to become steeper at the
toe.

Another sequel to laminitis is the disruption and (eventual) destruction
of the distal circulation. If the coffin bone sinks more than a minimum
amount at the toe, the circumflex artery will get squashed between the
rim of the coffin bone and the sole. It will initially attempt to
compensate by ramifying anywhere it can find space -- this will create
abnormal foraminae, usually several of them, and abnormal grooves on the
surface of
the coffin bone which develop due to the pounding pulse associated with
the disorder. Finally, if the coffin bone continues to sink, the
circulation will die and then the periosteum, as well as the bone in
this area will also die and start to necrose. Not long after this, the
horse will get septic poisoning and/or gangrene and will have to be
killed.

A horse operating with a coffin bone in the condition of the specimen
you present would not have been sound at any gait above a walk. This
does not
say to me that the Roman owners would have avoided making the animal go
faster; it only means that if it went faster, there would have been a
pronounced limp. It might have been maintained with out-of-balance,
laminitic feet -- the "ski feet" one occasionally sees reported in
modern cases of criminal neglect -- for years before the disease tipped
over far
enough to start the downward slide to necrosis. A ski-footed horse can
be kept in work by periodically sawing off the excessive growth at the
toe. I
do definitely envision this animal having the heavy, lobelike laminitic
rings, and knock kneed-toed out stance.

What in the modern world typically causes laminitis is the feeding of
grain (rolled oats and maize corn, particularly; barley is much lower in
glycemic load and I would not look to ground barley as a culprit. If you
have teeth from this site and they are polished, you may assume, I
think, that the animals were being fed ground barley. If you have no
polished teeth, then I'd assume they were pastured/fed hay, and in that
case, I'd
want to consult with the site paleobotanist as to which grasses were
likely to be found locally and/or in manure or stable refuse from the
site).

The other inducer of laminitis, and this would apply at all historical
periods and in all cultures, is the greening of the grass, especially in
springtime. "Sap" in grass is full of sugar, and the laminitis-prone
horse is one which, like a diabetic, can't handle a sugar overload, and
reacts symptomatically by the disruption of the distal circulation which
is the
major feature of laminitis.

There is a huge amount of information on laminitis/founder in modern
horses: look up Dr. Bowker of Michigan State University on the Internet
and have a look through his bibliography. Also, look at Dr. Chris
Pollitt's published work; he has a website from which you can get a
number of free and very useful PDF's of published papers. His "Atlas of
the Equine Hoof" is indispensable.

From my own website at www.equinestudies.org you can click on
"membership" and then look up the "Inner Horseman" back issue disk for
Year 2003. This
is essentially a book on "orthopedic principles in horseshoeing", and
what you'll be getting out of that for your $25 bucks is a 12-layer 3D
virtual dissection of the distal limb which I made, along with all the
anatomical detail pertaining to the musculoskeletal system, of which the
above is
only a sketch. -- Have fun -- Deb Bennett, Ph.D., Director
Equine Studies Institute & the bone lady at Vindolanda




> Dear all,
>
> I have a horse hoof that is affected by some sort of pathology,
> probably infection of some kind. The hoof is worn unevenly, one side
> more than the
> other. I can't tell whether it's the medial or lateral side. The hoof
> almost seem to curve upwards on that side. The too-worn side has
> porosities and minor bone growth on the side facing the ground. Does
> anyone here have any suggestion as to what might have caused this, or
> seen similar pathologies elsewhere?
>
> The site is a rural Iron Age/Roman rural settlement in southern
> England.
>
> Pictures here:
> Front:
> http://i893.photobucket.com/albums/ac137/ossamentaDW/Benbilder/P1020525.jpg
> Base:
> http://i893.photobucket.com/albums/ac137/ossamentaDW/Benbilder/P1020526.jpg
> Pathological side:
> http://i893.photobucket.com/albums/ac137/ossamentaDW/Benbilder/P1020527.jpg
> Normal side:
> http://i893.photobucket.com/albums/ac137/ossamentaDW/Benbilder/P1020528.jpg
>
>
> ------ Files attached to this email may be in ISO 26300 format (OASIS
> Open Document Format). If you have difficulty opening them, please
> visit
> http://iso26300.info for more information.
>
>
>


------
Files attached to this email may be in ISO 26300 format (OASIS Open Document Format). If you have difficulty opening them, please visit http://iso26300.info for more information.