LEGG-CALVÉ-PERTHES DISEASE
Fred Lanting © TheDogPlace.org
A disorder sometimes 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.
It has a history in human medicine, too.
In fact, that's where it was first discovered in 1910 by three researchers
working independently. Legg, Calvé, and Perthes each 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 Germany about the same time saw it mostly in
the Wires but also in a few other breeds Since then, puppies of many other
small, toy, and miniature breeds between 3 and 10 months of age have been
affected.
Symptoms And Diagnosis Of Legg-Perthes
Radiographic (“X-ray”) signs of Legg-Perthes are usually gross and the course
and outcome discouraging, since 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 does 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 to the hip (further away, the
opposite of proximal).
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. These are replacement attempts by the
body, similar to the attempt to replace bone that takes place during HD
remodeling; eventually there is 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. See
pictures at the end of this article.
Cause
Of Legg Perthes Disease
The most probable cause is a genetic weakness that allows abnormal or inadequate
blood supply to the ossifying epiphyses. Those are the ends or caps of long
bones that are changing from cartilage in the embryo to bone in the adult.
Depending upon breed and particular bone portion, 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 unproven
idea was that some of these little dogs have excess and premature levels of
androgen and estrogen hormones that influence this process.
Various Treatments For Hip Dysplasia
or Legg Perthes Disease
Various treatments have been suggested but the usual one is excision (surgical
removal) of the femoral head and neck, again with a similarity to one of the HD
operations 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 cases, 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 June 30, 1994 included a brief discussion by Paul Donohue, M.D., responding
to a reader's request for advice. Her 8-year old child had recently been
diagnosed with Legg-Calvé-Perthes disease and she had seen no improvement after
3 months in a brace.
By the way, human infants with HD are put into slings or casts which keep the
legs spread apart until the joint begins to strengthen; did you know that people
get HD, too? Anyway, Dr. Donohue told her that the Legg-Calvé-Perthes disorder
involved a cutting off of the blood supply to the epiphysis (top part of the
femur) and that it might take more than a year for the brace to rest the hip
enough so that restoration of blood supply can help restore bone there. If
unsuccessful after that long a wait, surgery may be needed, he advised. So you
see, your dogs are not the only ones at risk for this problem.
Some of us may not have heard of any of our specific breeds diagnosed with Legg-Perthes
yet, but that may be because, to many veterinarians, the radiograph looks like
hip dysplasia, and it is not sent in to experts for diagnosis and recording of
data. On the other hand, I have seen many HD cases mistakenly diagnosed as LCP.
If you come across a case of Legg-Perthes in your breed, please report it
(accurately, with name and address of person diagnosing it) to the health
committee and/or magazine editor of your club.
081215121604r3
SSI

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