Legg Calvé Perthes Disease
by Fred Lanting
A disorder sometimes
easily mistaken for hip dysplasia is Legg Calvé Perthes disease, perhaps
more frequently referred to by the dog fancier as “Legg Perthes”.
This is an aseptic (not infected), developmental necrosis (dying of tissue) of
the femoral head and neck, found almost entirely in toy or other small breeds.
On radiographs, it often looks as if the bone is "rotting away", and
lameness is the major or only symptom. has a history
in human medicine, too. As a matter of fact, that's where it was first
discovered in 1910 by three researchers working independently. Legg, Calvé, and Perthes saw a
flattening of the femoral head (coxa plana) in affected youngsters and thought that trauma was
at the heart of its etiology. Schnelle
in the 1930s first saw the disorder in the canine in Wirehaired Fox Terriers,
and Moltzen Nielsen in
Radiographic ("X
ray"} signs of Legg Perthes are usually gross
and discouraging, as many cases are not referred to the vet or the specialist
for diagnosis until the dog has been limping for a long time or the disease has
progressed to the point that it becomes a more real problem to the owner. These
small dogs put so little weight on their tiny hip joints that they almost can
compensate for discomfort by "walking on their forelimbs instead of their
four limbs". Many are couch potatoes" or spend much time being
carried, but even then, picking up an affected dog in a certain manner can put
more pressure on the joint than normal locomotion, so pain at that time is
often the stimulus to do something about it. Owners have reported
"incredible pain" and constant, progressive discomfort, inability to
stay long in any one position, and bone lysis (loss
through a process akin to dissolving or consuming) at other areas in the limb
distal (further away, the opposite of proximal) to the hip.
The earliest
radiographic signs, should you look for them before they change, include an
increased radiodensity (opacity as seen on the radiograph)
in the lateral part of the epiphysis of the femoral header Lateral means the
part away from the mid line or medial; the "outside". Resorption of necrotic (dying, rotting or decomposing) trabecular bone cells is next accompanied by a lysis (dissolving or being consumed) of bone, replacement
attempts by the body (similar to the attempt to replace bone that takes place
during HD remodeling), and eventually fracture or
collapse like a frame house riddled by termites. As HD may or may not be
concurrent, the congruity of the ball and socket coxofemoral
joint might still be maintained until collapse.
Cause
The most probable cause
is a genetic weakness that allows abnormal or inadequate blood supply to the
ossifying epiphyses. That's the ends or caps of long bones which are changing
from cartilage in the embryo to bone in the adult. Depending upon breed and
particular bone portion, all ossification is usually complete by 12 months of
age. Compression/pinching of the blood vessels in that area
leads to the necrosis (death) of cartilage and bone tissue. One idea was
that some of these little dogs have excess and premature levels of androgen and
estrogen (hormones) that influence this process.
Treatment
Various treatments have
been suggested but the usual one is excision (surgical removal) of the femoral
head and neck, again with a similarity to the operation performed on dogs.
Conservative treatment
(as opposed to 'heroic measures such as surgery) has been suggested for those
unilaterally limping dogs (lame on only one side and supported well by the
other limb) with good congruity and no collapse or deterioration. The dog's
worse limb is put into an Ehmer sling for a time,
perhaps as much as a couple of months, then the dog is kept in a crate to minimize
activity for another few weeks perhaps, during which time the dog is
periodically radiographed. If this approach is
successful, the resorbed bone is replaced in a normal
manner and radiopacity returns, indicating normal
bone cells and regained strength. In such an incidence, aseptic necrosis is
halted and then reversed by keeping the dog's weight off the limb. Lameness has
been reported to cease in perhaps a quarter of dogs treated conservatively, but
much of this estimate depends on owners' reports rather than always being
followed up by veterinary examination.
A syndicated column
called "To Your Good Health" in the Clarksburg (WV) Telegram of
Some cases of Legg-Perthes go unreported or misdiagnosed. To some
veterinarians, the radiograph looks like hip dysplasia,
and it is not sent in to OFA, GDC, or PennHIP for
diagnosis and recording of data. If you come across a case of Legg Perthes in your non-toy breed, please get me a copy of the
radiograph and medical report, even if only on loan till I can make a copy for
my orthopedics files. Thanks. Send them to me at
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Copyright 2001 Fred Lanting, Canine Consulting.
Mr.GSD@juno.com. All rights reserved. Please
view his site Real
GSD.
NOTE: A well-respected AKC and Schaferhund
Verein judge, Mr. Lanting has
judged in more than a dozen countries, including the prestigious FCI Asian Show
hosted by Japan Kennel Club, the Scottish Kennel Club, a Greyhound specialty in