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ORTHOPEDIC PROBLEMS
IN HOCKS
Fred Lanting
(as printed in Mastiff Reporter, 1995; revised 2007 for SiriusDog.com and
other media)
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Osteochondrosis is a term applied to a number of similar disorders of the
joints where bone (osteo-) and cartilage (chondro-) are involved. If they
are inflamed we use the term osteochondritis. It is now a fairly common diagnosis
in young limping dogs, the defects being found in one or more of those joints
I named above. The hock joint is what corresponds to our ankle and first short
bones in the foot, though the dog does not walk on the heel as we do. In
the hock, the large bone of the lower thigh (tibia) rests mainly on the tibial
tarsal bone, also known as the talus. The common specific expression of osteochondrosis
in the hock is OCD (osteochondritis dissecans), which means, as it does in
the shoulder and the elbow, a small piece of cartilage or bone has come loose
in the joint of a young dog and is causing irritation and inflammation.
INCIDENCE OF OCD
Sweden's Dr. S.E. Olsson reported
on 51 dogs with hock ailments, 48 of which had a diagnosis of OCD of the
hock, and the other 3 having osteoarthritis in the joint but no real sign
of OCD. In all but one of the 48, the site of this osteochondrosis defect
was associated with the rear part of the medial (toward the middle) ridge
of this bone. Labrador Retrievers made up 23 of these dogs in Olsson's 1984
group, with 10 Rottweilers, 6 Golden Retrievers, and smaller numbers of Beagle,
Newfoundland, Schnauzer, GSD, Bouvier, and Welsh Springer also being included.
Ten had lesions in both hocks. About half the flaps or mice were all cartilage,
and 25% each were bone or both, the bone sometimes being formed by ossification
rather than being pulled off. As in OCD of the other joints, this one begins
with a defect in cartilage rather than a fissure in bone.
In conversations with radiologists
at Auburn University, I was told that they see tibial-tarsal OCD most predominantly
in Rottweilers, a breed they also connect frequently with OCD of the humeral
head and even panosteitis.
In Australia, OCD of the hock is also seen in Bull Terriers.
In a later study of 89 dogs, Olsson
concluded that “osteochondrosis of the hock does not show the same preponderance
for the male sex” as seen in other joints. He surmised that this difference
was connected with the fact that hock lesions are much more associated with
a history of trauma. Heritability, therefore, may be lower for this ailment
than for others. However, before you get confused between heritability and
inheritance, you may want to read my new book on orthopedic disorders, unfortunately
not yet in print as of the time of this article's publication. For now, suffice
it to say that they are not the same: heritability is a description of how
environment can influence the expression of genes, and inheritance refers
to the actual chemical structures we call genes being replicated and passed
along in the formation of sperm and egg cells.
TREATMENT
Prompt surgical treatment is as
much recommended in the hock as it is in the elbow. If surgery is delayed
until severe DJD has started, permanent lameness is very likely even after
surgery to remove calcium deposits or particles. Even if diagnosed early,
a few cases will have a poor prognosis for recovery and freedom from limping
and DJD.
GENETICS
Mason and Lavelle in 1979 found a familial characteristic in Australian
Cattle Dogs. (Remember the early historical connection between this breed
and the Shiba through the southern Asia Dingo.) A year later they and a couple
more colleagues studied 68 dogs, half of which were Labrador Retrievers,
bred by the National (Australian) Guide Dogs Association. When the pedigrees
of the Labs were analyzed, it was discovered that most of them went back
to one foundation bitch, and that the odds of any of these dogs developing
osteochondrosis were greatly increased if both parents had that bitch in
their pedigrees.
ADDITIONAL COMMENTS ON OCD
OF THE HOCKS
In the 1970s, Olsson reported
a number of observations which were presented in the following 2 paragraphs,
copied from his contribution to my 1981 HD book (out of print now and supplanted
by the new “Canine Orthopedics” book): “OCD of the hock may not be as common
in your breed as in Labs, Rotts, and Goldens, but it is found in individuals
of many breeds and it is wise to give attention to its possibility in cases
of slight to severe lameness in the hind legs of young dogs. The clinical
signs usually begin at 4 to 5 months and are usually very vague. The lesion
is more often unilateral than OCD in other joints. The most typical findings
are a slightly shorter step than normal on the affected leg and pain on extension
and flexion of the hock. Rather early, the range of flexion is decreased.
In some dogs there is obvious joint effusion (swelling). As in OCD of other
joints, the radiographic examination (X-rays) provides the diagnosis. The
lesion is located to the medial ridge of the talus and is best demonstrated
as a defect in this ridge on an anterioposterior film picture. A fragment
can often be seen because it is calcified or ossified. In old cases the fragments
can be very large in size. Sometimes a lateral radiograph with the hock joint
in as much flexion as possible is useful.
“A rather high percentage of loose
bodies removed from hock joints contain bone. This is in contrast to OCD in
other joints of the dog, where such ossicles are extremely rare. Surgery is
the treatment of choice. With the leg in flexion, the loose bodies easily
can be removed. Prognosis is good if surgery is performed early.”
A SIMILAR CONDITION
Stress fractures of the hock have
been well known in racing Greyhounds for many years. However, these can and
do occur very occasionally in other breeds. It is bittersweet irony that it
should have first been reported in a Shiba belonging to the author of the
book on orthopedic disorders, namely me. The day after winning another Best
In Show, my male suffered a very painful fracture in the hock as a result
of jumping into a jumble of large rocks. “Track” Greyhounds avulse (tear off)
a fragment of bone when they exert those tremendous and sudden tensile forces
in racing. My Shiba did the same thing, apparently when bouncing out of a
crevice between rocks while the hock was twisted. This severe trauma can
be (and was, in this case) accompanied by the creation of a slight but significant
subluxation between the talus and the several tarsal bones below it, adding
to the pain. Surgery about a week after the injury was followed by hydrotherapy
and restricted free exercise, and recovery was apparent, but occasional limping
was still seen, thought at the time to be due to intermittent arthritis.
Arthritis, consisting of swelling and usually some extra bony (“calcium”)
deposits is a natural result of injury to a joint. However, when the limp
returned a year later, further radiography revealed a previously-undetected
avulsed fragment, and at the veterinary college this was removed and a plate
affixed with pins. Since he had normal gait most of the time, I “brought him
out” for a short series of shows, but following Murphy's Law, he limped at
those shows. Since then he's been happily retired with his 8 international
championships and lady-Shiba visitors, though he still thinks we're going
to a dog show when he sees his crate and my suitcase together!
Stress fractures (acquired, environmental)
can be differentiated from genetic OCD mainly by the age of onset, the former
occurring after full skeletal maturity has been reached and at an age when
the dog is in top muscular condition. They are brought on suddenly, like a
muscle strain or a bone broken in a fall. OCD of the hock occurs in young
pups whose joints have bones that are still ossifying (turning to bone from
cartilage and connective tissue) and thus in a very “plastic” form, easily
distorted by less severe but constant stress. Minor subluxation may accompany
stress fracture, while subluxation can range from minor to severe in congenital-developmental
joint disorders. The OCD lesion is found on the top end of the talus, while
the stress fracture avulsed piece is torn off the bottom. Stress fractures
almost always show an obvious bone fragment on the X-ray picture, but more
often than not, the OCD lesion is either all cartilage or hard to find on
film, sometimes because bone has been partly or completely resorbed. The occurrence
of stress fracture in the Shiba is probably very rare (mine is the only case
I have in my files so far), while hereditary OCD of the hock is common enough
so that an owner of a dog with rear-leg lameness should have this possibility
checked by a team of radiologist and orthopedist,
probably at a veterinary college.
A DIFFERENT CONDITION
There is another, less serious,
condition in the hock that poses no special problem in regard to veterinary
bills and very little interference with leading a fairly normal life. It is
commonly known as “slipped hocks”, but more accurately described as luxation
(when completely out of alignment or position) or as subluxation (looseness,
but retaining some positional relation, which is far more commonly found).
Three of the illustrations accompanying this article are tracings from my
own radiographs — two normal and one showing subluxation in the flexed position
— and the other one is from the classic veterinary text by Miller, Christensen,
and Evans. The condition shown in Figure 4 can evidence itself in a “double-jointed”
or “super-extended” position. In the vernacular, “bending the joint backwards.”
I have seen “slipped hocks” in Shar Peis, Chows, and a few Afghans, and feel
sure that it exists in many others.
Fred Lanting is an internationally respected show judge, approved
by many registries as an all-breed judge, has judged numerous countries’ Sieger
Shows and Landesgruppen events, and has many years experience with SV. He
presents seminars and consults worldwide on such topics as Gait-&-Structure,
HD and Other Orthopedic Disorders, Anatomy, Training Techniques, and The GSD.
He conducts annual non-profit sightseeing tours of Europe, centered on the
Sieger Show (biggest breed show in the world) and BSP. All Things Canine
-- consulting division, Willow Wood Services Phone: 256-498-3319 Fax: 256-498-3311
E-mail mr.gsd@netscape.com
Canine HD and Other Orthopedic Disorders by Fred Lanting.
It covers all joints plus many bone disorders and includes genetics, diagnostic
methods, treatment options, and the role that environment plays. This new
"Hip Dysplasia and Other Canine Orthopedic Disorders" book is a comprehensive
(nearly 600 pages!), amply illustrated, annotated, monumental work that is
suitable as a coffee-table book, reference work for breeders and vets, and
a study adjunct for veterinary students, for the dog trainer and the general
dog owner of any breed.
The Total German Shepherd Dog by Fred Lanting
Copyright August, 2007 - 2007
reprinted with kind permission from Fred Lanting
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