
Craniomandibular Osteopathy (CMO)
in the Scottish
Terrier
What is Craniomandibuar Osteopathy?
Craniomandibular Osteopathy (CMO) is a painful,
non-cancerous, inherited disease that involves excess bony
growth in immature dogs. Lion Jaw, Scottie Jaw and Westie
Jaw are other names. CMO affects mandibles (jaws), sometimes
temporomandibular joints, occasionally skull bones, even
rarely long leg bones. CMO is a disease no breeder wants to
produce!
What are symptoms of CMO?
- Pain during chewing or jaw manipulation
- Swollen jaws
- Drooling
- Intermittent fever
- Lethargy
- Lack of appetite
- Mouth may not open well
First clue may be reluctance to chew. CMO is a cyclic
disease, with episodes of bone resorption and proliferation.
Symptoms run in I 0- to 14-day pain/fever cycles. Severity
varies. A few dogs may not open their mouths unless treated.
Some dogs have mild symptoms; others have no symptoms.
Can CMO puppies become healthy pets?
Definitely! CMO is unusual. It is a disease of the
young--one to "get through." CMO is painful for dogs,
unpleasant for owners, and a roadblock for breeders.
However, it runs its course by about one year of age. Once
symptoms are gone, CMO does not affect later life.
Characteristic bony growths of- ten disappear in adults. CMO
is a short-term problem for owners and puppies to “survive.”
It affects the young, then resolves itself. Owners are
relieved to learn their puppies will recover and live a
normal life span. Only rarely should a CMO-affected puppy be
put down. Because the disease is misunderstood, some CMO
puppies are euthanized needlessly.
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When and how is CMO diagnosed?
Usual onset is four to IO months, but four to seven
months is most common. Initial diagnosis is from symptoms.
Experienced breeders and veterinarians can identify CMO
earlier by recognizing subtle clinical signs and palpating
the bony growths.
How can I be sure it is CMO?
X-rays confirm clinical diagnosis. Survey radio-graphs of
the skull and mandibles including oblique, dorsoventral and
lateral views, are recommended. For definitive diagnosis, a
board-certified veterinary radiologist can evaluate x-rays
taken by a puppy’s own veterinarian. To document unaffected
status of dogs in breeding programs, x-ray before six
months. Light cases may not be apparent later on x-ray.
What is the treatment for CMO?
Analgesics and anti-inflammatory drugs, including
corticosteroids, reduce pain and help puppies open their
mouths to eat and drink. Recognizing onset of pain cycles
early is important. Medications must be administered while a
puppy will let its mouth be opened. Feed a high calorie,
protein rich gruel or soft diet, limit chew toys and make
tug-of-war games and roughhousing off limits.
Do other breeds have CMO?
First mention of CMO in veterinary literature was 1958.
Forty years later, Dr. George Padgett's book Control of
Canine Genetic Diseases (1998) shows 31 breeds affected by
CMO, far more than veterinary texts reflect. Eleven are
terrier breeds: American Staffordshire, Border, Bull, Cairn,
Dandie Dinmont, Kerry Blue, Scottie, Skye, Soft-Coated
Wheaten, Staffordshire Bull and Westie. More recently a
Smooth Fox Terrier also has been reported.
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How common is CMO?
Club health surveys show a “guesstimated” CMO carrier
incidence of.
Scotties 4.7% (1995),
Cairns 13.59% (1999) and
Westies 22.1% (1999)
How is CMO inherited?
Test breedings proved CMO is inherited by an autosomal
recessive gene, at least in the three prime affected breeds:
West Highland White Terriers, Cairn Terriers and Scottish
Terriers. Both parents of an affected puppy are carriers of
the CMO gene. Two carriers bred together statistically will
produce 25% affecteds, 50% carriers and 25% non-carriers.
Siblings of affected puppies have a 66 2/3% chance of being
carriers. Offspring of known carriers have a 50% chance of
being carriers. Affected dogs should be bred only in test
matings to "clear" breeding stock. Breed known carriers only
with great caution.
How can CMO be prevented?
Dogs which have produced CMO should be removed from the
breeding pool, unless a breeder uses only low risk mates,
accepts responsibility for affected pups and treats all
offspring as possible carriers. Test breeding an affected
dog to a mate of unknown carrier status is an accepted way
to discover the odds that the tested dog can be used safely
in a breeding program without producing affected pups or
passing on the CMO gene. Documenting widely used sires as
“clear” by test breeding is valuable! Offspring from test
breedings are usually spayed or neutered since they carry
the disease gene. Registries, pedigree risk analyses and
diagnostic x-rays to prove future breeding stock is not
subclinically affected are other ways responsible breeders
try to prevent CMO. Westie and Cairn breeders pioneered
these techniques against CMO, and Scottie breeders use them
too. Research is underway to develop a DNA test to identify
CMO carrier status.
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Additional Information
CMO DNA Research
Scottie, Westie and Cairn health foundations are funding
half the AKC Canine Health Foundation's research to develop
a DNA-based diagnostic test for CMO in the three breeds.
Thanks to Scottie owners for $15,000 toward the $90,000
expended by 2002!
To participate in CMO DNA collection,
contact:
Dr. Patrick Venta at
Michigan State University
(517) 355-6463, ext. 1561
fax (517) 355-5164
E-mail:
venta@cvm.msu.edu
DNA from affected dogs, their siblings, parents,
grandparents and other close relatives is valuable to CMO
research. Samples are easy to collect at home with free
brush collection kits available from Dr. Venta.
Helpful CMO References:
“Craniomandibular Osteopathy” by Anne Sanders (http://www.westieclubamerica.com)
outlines protocol for prednisone treatment. Westie breeder
Sanders has advised owners of many breeds on CMO and can be
consulted at:
Email:
ASanders@Starband.net
(360) 629-6434 (PST)
33101 44th Ave. NW,
Stanwood, WA 98292-7106.
“CMO, The Basics of a Painful Disease,” “CMO: Breeders
Say…” and other articles are available through
STCA’s
ScottiePhile Health Database. Contact: Susan Morris,
ScottiePhile Co-Chairman
P. 0. Box 427,
Onalaska, WA 98570-0427
360-262-3097
E-mail:
susanm@stomowayscots.com or
Gail Gaines,
ph. (615) 298-1240
E-mail: gneidfyre@aol.com
Copyright 2004
Scottish Terrier Club of America
Health Trust Fund
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