Hip Dysplasia in the Boykin Spaniel
Canine Hip
Dysplasia (CHD) afflicts millions of dogs each year and can
result in debilitating degenerative joint disease (DJD) of the
hip. Many Boykin Spaniels will suffer from osteoarthritis, pain,
and lameness, costing owners and breeders millions of dollars in
veterinary care, shortened work longevity, and reduced
performance.
CHD was first described in 1937 by Dr. Gerry B. Schnelle. In
a paper entitled Bilateral Congenital Subluxation of the
Coxofemoral Joints of a Dog Schnelle writes: "The
condition described herein, rare though it may be, should be
recognized as being congenital and potentially hereditary, and
the dog or bitch in which it occurs should be destroyed or
sterilized in the eugenic interests of the breed."
In 1966, Henricson, Norberg and Olsson refined the definition
of CHD describing it as: "A varying degree of laxity of the
hip joint permitting subluxation during early life, giving rise
to varying degrees of shallow acetabulum and flattening of the
femoral head, finally inevitably leading to osteoarthritis."
Unfortunately,
the Boykin Spaniel gene pool does have a high prevalence for
CHD. OFA has documented in its database 1614 case reports from
January 1974 through December 2004. The percent found to be
dysplastic is 39.6%. On the other end of the spectrum, those
found to be rated "Excellent" are only 0.9%. This brings the
Boykin's ranking of all dog breeds recorded in the OFA to 9th
overall. Considering that there are hundreds of breeds recorded
this is indeed a very poor ranking. The statistics changed with
the inclusion of the 2005 results, lowering the Boykin's rank to
11th, with 1804 total reports to date, 1.1% Excellent rated and
38.2% found to be dysplastic.
It should be
noted that environmental factors such as proper diet and
exercise can reduce pain and suffering but will only mask the
underlying problem. The dog is still genetically unsound and
without breeders addressing genetic problem in future breedings
the incidence of CHD within the breed will continue.
CHD is a
developmental disease meaning that it is not present at birth,
but develops with age.
The only way to reduce and eliminate CHD from the breed is to
screen potential breeding stock for the disease and remove
afflicted individuals from their breeding program. Ultimately,
detailed records should be kept on not only the breeding
individuals but also their littermates as well as their
offspring who may indicate whether the disease may be a
recessive gene that is expressed through these relatives.
Clinical Signs of CHD
An affected dog may have one or any combination of the
following clinical signs:
- Presentation: 5 months to 12
months for the severe form of hip dysplasia; later for
the chronic form
- Abnormal Gait
- Bunny-hopping When Running
- Thigh Muscle Atrophy (loss of
muscle mass)
- Pain
- Low Exercise Tolerance
- Reluctance to Climb Stairs
- Audible "click" When Walking
- Increased Intertrochanteric Width
("points of hips" are wider than normal)
Other conditions of
the hip can mimic CHD; Clinical signs by themselves do not
necessarily mean that a dog has hip dysplasia. Screening tests
such as OFA and PennHip should be used to identify the disease
and degree of affliction.
Screening Tests to Detect CHD
As technology advances, the
veterinary professional community will offer and utilize
improved methods of disease diagnosis. The two most widely
recognized testing and certification programs in the United
States are OFA and PennHip. OVC is also acceptable, although not
widely used outside of the Ontario, Canada area.
OFA
OFA requires that dogs be over 2 years old for hip
certification. Puppies as young as 4 months of age may have
their x-rays submitted for “preliminary evaluation” If the dog
is found to be dysplastic at an early age, the economic loss
from the cost of training, handling, showing and so forth can be
minimized and the emotional loss reduced. For the prelim results
to be released on the OFA database the dog must be at least 12
months old at the time of the x-ray and the dog must be
permanently identified via microchip or tattoo.
Owners of dogs who are x-rayed by their veterinarian have the
option of entering their dog into the OFA database.
This "prescreening" practice has
been shown to result in a biased database containing a greater
frequency of non-diseased hips than actually exists in the true
population. Excluding the worst hips leads to a false impression
that genetic progress is being made. All owners and breeders
should be encouraged to enter all of their results into the
database to help give the most complete results on the health of
the breed.
Reading an OFA Hip Certificate
OFA Hip Certificate
Example: BY-1000E38F-PI
·
BY
= Breed code, in this case a Boykin Spaniel
·
1000
= Ascending numerical identifier given to each animal within a
breed evaluated as normal and given a number, in this case the
1000th Boykin Spaniel to be given a number
·
E
= The phenotypic OFA evaluation, in this case E = Excellent,
other normal phenotypes include G (Good) and F (Fair)
·
38
= The age in months when the testing was done, in this case 38
months
·
F
= Sex, in this case a male
·
PI
= Indicates that the animal has been permanently identified in
the form of tattoo or microchip. If the animals lacks
permanent identification, a suffix of NOPI is applied
The OFA website and online searchable databases can be found
at www.offa.org
PennHip
PennHIP
(University of Pennsylvania
Hip Improvement
Program) incorporates a method of
multifaceted
radiographic technology (x-ray)
reviews to
evaluate hips. It is accurate in puppies as young as 16 weeks of
age. Identifying afflicted dogs at such a young age allows
breeders, owners and trainers adjust their plans for the dog's
future accordingly.
The general
veterinary consensus is that hip dysplasia is hip joint laxity
resulting in osteoarthritis and that the
degree of hip joint laxity has
been shown to be the most important risk factor in determining
whether a dog is prone to developing CHD. The PennHIP
method is a different way to assess, measure and interpret hip
joint laxity. It consists of three separate radiographs: the
distraction view, the compression view and the hip-extended
view. A dog's hips are given scores to indicate the amount of
laxity present.
It
is mandatory that all hip radiographs by PennHIP veterinarians
be submitted for analysis and inclusion in the PennHIP database.
Veterinarians must have special training and certification
directly from PennHip to be able to perform these screening
tests. Due to the additional x-ray views and other expenses
PennHip examination is more expensive than the traditional OFA
exam.
More information
about radiographic procedures or to find a certified
veterinarian can be found at
www.pennhip.org
OVC
Ontario Veterinary
College (OVC), the oldest
veterinary college in Canada and the United States,
is also an acceptable program but rarely seen outside of Canada
or the most northern state in the US.
www.ovc.uoguelph.ca is
their college website. Howard Dobson, DVM in Diagnostic
Imaging (Phone: (519) 823-8800 x 4000) is the contact for OVC
hip evaluations.
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