I often
get asked "what's the real difference between OFA and PennHip".
I am going to attempt to answer that question here without
getting into the extreme technical issues involved as well.
It would
most likely take me hours to really go over the major
differences between the two systems, the pros and cons of each
and WHY they don't always agree. I will try to simplify it
a little here. Everybody tries to compare the two. There
really is NO comparison – they may both be fruits, but they are
most definitely NOT the same fruit.... just as an Apple does not
equal a Peach.
I will
agree that both techniques, PennHip and OFA, are means of
scoring hips, however, just because you score well with one
system does not mean you will score well with the other system.
THEY DO NOT MEASURE THE SAME THING. THEY ARE NOT EQUAL.
If you get an average score on PennHip, that
does NOT necessarily equal a FAIR score on OFA.
If you get an EXCELLENT score on PennHip, that
does NOT necessarily mean you will even PASS an
OFA. Make no mistake, they DO NOT compare.
OFA measures how DEEP
the hip fits in the socket. PennHip measures how TIGHT does the
hip stay in the socket.
What does this mean?
Here
is your glossary:
- Acetabulum - the "cup" on the
pelvis that the head of the femur fits in forming the
hip socket. It can be deep (a cup), shallow (a
saucer), or somewhere between.
- Femoral head - the ball-shaped
top of the thigh bone that fits into the acetabulum.
- The "string" - the series of
ligament, tendons, and cartilage that forms the joint
capsule and surrounding tissue that holds the hips
socket together
- Life - Represented by the
tailgate of the truck on a bumpy road.
- Arthritis - what happens when
the ball either moves around too much in the cup/saucer
or falls off of it completely.
With OFA,
they want to see a deep cup (acetabulum) with the ball (femoral
head) down deep inside it. Obviously this is important - if you
are trying to take something with you down the bumpy road of
life, it is better to take it in a "cup" than a "saucer". And
the deeper, the better.
On the
other hand, PennHip does not really care how deep the hip fits
in the socket, it merely evaluates how much movement "in"
(Compression) and "out" (Distraction) of the socket there is.
In other words - Does it STAY in the socket.
The
comparison that I use for this example is similar to the OFA
comparison. If you were riding down that same bumpy road of life
on the tailgate of the truck, we have already determined that if
you wanted to take, say a ball, with you, it would be much
better to have that ball sitting in a cup rather than a saucer.
But let's take it one step further. Let's say that we could
actually anchor that ball into either the cup or the saucer by
using a string (ligament).
-
If that
ligament is too long, you increase your risk of the ball falling
out of your cup/saucer. So, obviously, we would want a string
that is very short and very tight. If the string is very short
and very tight then you would get a good score on your PennHip.
However, even if the string is very short and very tight, if the
ball is sitting inside of a saucer instead of a cup, or if the
ball simply does not fit in the cup at all (incongruity in the
joint) your OFA's will be very poor.
-
Now let's
look at it from the opposite direction. Let's say that you
definitely have a cup that you're working with. Let's say that
the string (ligament) that holds the ball in the cup is very
long. Now, you will most likely have a very good OFA score but a
very poor PennHip score.
-
Or, what
if you have a saucer that you're working with and a very long
string? Chances are that you will not go very far down that road
of life before your ball falls out of your saucer (aka - your
dog starts showing arthritis). You would have most likely had a
poor OFA score and a poor PennHip score.
-
What if
you have a saucer and a very short string? The ball most likely
will not fall off from the saucer. This will equal good PennHip
scores and poor OFA scores.
So what
does it all mean? Here at Sequoyah Shepherds we feel that it is
important to have both passing OFA scores, as well as good
PennHip scores (PennHip doesn't actually give you a pass or
fail, they give you your dogs scores when compared with other
dogs of ONLY that same breed - these are given in percentages
....i.e. your dog is better that 70% of the breed, or your dog
is in the top 30% of the breed).
The nuts
and bolts of it are these.……
If you
have a deep acetabulum (good OFA scores) where the ball will fit
down deep into the hip socket, you are less likely to have wear
and tear on the acetabulum itself because the ball obviously is
more likely to stay put. However, if you don't have a good
PennHip score, meaning the ball actually stays in the hip
socket, it really doesn't matter how deep it actually will fit
in the socket if it won't stay there. That's kind of like
putting a wheel on an axle - if you don't anchor it down, it is
going to fall off eventually when you go
down the road. So, IMO, it does not matter how good your OFA scores are if your dog
cannot get a decent PennHip score.
Conversely, even though a dog passes his PennHip, does that mean
you can ignore OFA? You should easily be able to tell that
if the femoral ball is sitting on a saucer instead of a deep
acetabulum, even with a short "string" or ligament, there is more likely to
be "play" in the hip socket. Any movement in the joint that
indicates laxity, increases the risk of arthritis.
I, personally, am going to tell you that I feel that
70-80% of all German shepherds have hip dysplasia. What does
this mean? What exactly
is hip dysplasia? As a veterinarian, I have submitted
numerous radiographs to OFA. Some of them have come back
"dysplastic" with no arthritis and some have come back as
"passing". I have resubmitted radiographs on dogs that
were judged as "dysplastic" at 2 years of age and THOSE EXACT
SAME DOGS came back as "fair" at 6 or 8 or 10 years of age.
I have also resubmitted rads on dogs that were "GOOD" at 2 year
of age that "became" dysplastic years later. The fact is
that
"arthritis" = "hip dysplasia". Hips
aren't technically dysplastic until you are see arthritis
present even though OFA might grade them as "dysplastic" at
present WITHOUT arthritis. OFA scores come from a panel of
3 experts who, based on their opinions, judge the likelihood
that the dog in question will become "dysplastic" or "form
arthritis" at some point.
I have
stated that 70-80% of all German Shepherds have hip dysplasia.
Most everyone that hears that statement is appalled - either by
the statics or with my opinion, as most breeders (and even OFA)
says that only 18% or so have hip dysplasia. If I told
you that I had a 11-year-old German shepherd who was starting to
get some arthritis in his hips, would any of you think that was
abnormal? I dare say that most of you would not. How is that any
different from arthritis that develops at three or four years of
age then? It looks the same on a X-ray. It feels the same
to the dog. Why is it then that we call it "arthritis" at 10
years of age and "hip dysplasia" at 3 years of age? Why did one dog get it at three years of age and
another dog get it at 11 years of age? Why do some dogs never
get it at all, no matter what kind of sports, agility, or other
strenuous activities they have engaged in throughout the years?
Well, let's
take a moment to look at people. I am also going to tell you that 70-80% of
all people have knee problems = arthritis (at some point in
their life). Many older people (just like dogs) have
arthritis to some extent but not enough to affect them in any
significant way. As, we are fond of saying in the
veterinary world, "dogs (humans) walk on their hips (knees), not
their xrays". Many dogs/people have arthritis and show
absolutely NO sign of it whatsoever. Owners love to come
in and say things like "my last dog lived to 12 years old and he
NEVER had any arthritis". "Did you xray him?" "No".
"How do you know then?" ???
So what
determines "how", "when", or "if" your dog will get arthritis
(or "hip dysplasia")? The
answers to these questions are not simple but instead are
wrapped tightly within the bounds of genetics, environment, and
other factors affecting the development of these dogs through
the years.
Many
breeders will tell you that environment plays a biggest role in
the development of arthritis. I, personally, do not
believe it is true but there is something to be said for this
argument.
Now
let's get back to people..... If you have a person that played
football professionally through most of his adult life and
retires at 40 years of age, none of you would be surprised to
find that he has arthritis in his knees, even if he has NEVER
suffered an actual knee injury. Why? The obvious answer is that
he participated in a sport that environmentally dramatically affected his
knees through the years. However, explain to me why there are
some men who have play football professionally throughout their
life and at 40 years of age still have excellent knees.
ANSWER: Genetics.
If that
same man who played football and developed arthritis had spent
most of his life as a white-collar worker sitting behind an
executive desk, would he have gotten arthritis? The answer is.…
Maybe. It would've depended on how "bad" his knees actually were
- how loose were the ligaments? how deep were the sockets?
Just as with some dogs, no matter what you do,
they are going to develop arthritis at a very early age. Those
same dogs, if they are put through strenuous activities at an
early age, such as agility, Schutzhund, Frisbee, etc. will
generally develop much more severe cases than if they spent
most of their life in mild to moderate activity range with a
normal to lean bodyweight.
So, yes,
environment does play a significant role in the development of
arthritis. But what about GENETICS?
Now, let's go back to the guy who played football and did not
develop arthritis. The long and short of it is..... he had
excellent genetics to begin with. When you have excellent
genetics to begin with, ENVIRONMENT will play LESS of a role
than if the genetics are questionable to poor.
So what
does all this mean? It means, if you were lucky enough to get a
dog out of the top 20% orthopedically in the German Shepherd
breed, you have struck gold, my friend. You don't have to worry about whether your dog jumps in and out of the back of
your truck, you can go out and play Frisbee with your dog at an
early age, you can start agility whenever you want, you can lead
a perfectly normal life without having to worry about the
developmental stages of your dogs hips. How do you know if your
puppy is one of those dogs? The plain and simple answer is
......you don't. Or, at least you don't into your dog turns 12
years of age or so. No amount of research, testing, X-rays, or
pedigree studies will be able to truly answer this question for
you at this point in time. No breeder guarantee will assure it for you. You can simply
do your due diligence and hope for the best. That is what most
of the breeders who are offering the longer-term hip guarantees
are doing as well. Most of us know what type of dog our dogs
are. Most of us know what type puppies they generally produce.
Most of us know what type dogs are in the pedigrees. Does this
mean that we can absolutely 100% guarantee that your puppy will
be hip dysplasia free? Absolutely not. But most of us feel
pretty confident that we are doing everything possible to ensure
the best genetics that we can and are willing to take that
financial risk for you because we are striving to be able to
produce that "perfect" puppy.
By using
both OFA and PennHip as means of evaluating the quality of the
breeding dog, breeders can better assess the likelihood of those
dogs passing on "fair" to "poor" genetics. Does that mean
you don't have anything to worry about? Does that mean you don't
have to use a little common sense? Absolutely not. Though we do
our best to ensure that the dogs we are breeding are as close to
that top 20% as we can get, none of us are willing to stake our
life on the fact that YOUR puppy will never develop arthritis.
There are too many factors involved in the genetics that we
simply do not completely understand at this point that are
affecting the quality of the offspring. Two very nice
breeding dogs can produce puppies with poor quality hips (or at
least hips that are not of breeding quality). That is why
here at Sequoyah Shepherds every one of our pups will be placed
on limited registration and that registration WILL NOT BE LIFTED
until both the hips and elbows are xrayed to prove that the dog
is acceptable orthopedically. (There are other restrictions as
well but we will focus on orthopedics here. This
requirement also
helps us to know what our breeding dogs are producing so that we
can improve our breeding program.
So,
back to environment .... There are things you can do to decrease
the risk of developing arthritis in your puppy should he/she
GENETICALLY not fall in the top 20-30 percentile. If your
puppy does not happen to be in the top percentages, obviously it
would not be a good idea to take him out and start doing frisbee
work with him during the formative stages of his joints.
Obviously, it would not be a good idea to feed a poor quality
food that has a disproportionate calcium / phosphorus ratio or
excessive amount of calcium within the food – this, too, will
hurt the formative stages of his joints - nor do you want to
allow him to gain weight to fast or become excessively heavy.
So what it
boils down to is.... everyone has a role to play. A breeder should
do the best they can to ensure that they are dealing with the best
genes, and you, as the owner, needs to make sure that your puppy is
fed properly, maintains the proper weight, does not participate in
high impact activities at an early age, and stay in contact with
your breeder reporting back on any problems that you may have with
your puppy. This feedback will not only help ensure that your
breeder is able to assist you in any way they can, but it will also
help them to be able to better select the good genes out of the gene
pool and therefore improvement their breeding program and the
perpetuation of excellence in the GSD breed itself. With
everyone working together, we will help improve the quality of the
life of the breed we all love.
And I, for
one, feel that one of the best ways that we as breeders can help
ensure the best genetic material being passed on to the offspring,
is by performing both OFA's AND PennHips and expecting our breeding
dogs to pass both scoring systems. Is it fail-safe? No,
but it is by far better than any other system out there.
I know this
was a bit of a ramble, but hopefully it has helped clear up some of
the misconceptions with the German Shepherd, their hips, and their
hip scores. Feel free to give me a call or email me if you have any
questions or input. As I have time, I may also add comparisons
to this page of some of the other scoring systems that are used in
Canada and abroad. Thanks!
THE CHART:
Genetics vs Environment
Equals......
|
Genetics: |
OFA: |
PennHip: |
Environment: |
Results: |
|
Loose ligament and shallow cup |
Poor |
Poor |
Poor |
Arthritis Early |
|
Loose ligament and shallow cup |
Poor |
Poor |
Good |
Arthritis Later - but still gets it |
|
Loose ligament
and Deep Cup |
Good |
Poor |
Poor |
Arthritis MOST LIKELY early |
|
Loose ligament and Deep Cup |
Good |
Poor |
Good |
Arthritis MOST LIKELY later |
|
Short ligament and Shallow Cup |
Poor |
Good |
Poor |
Arthritis POSSIBLE depending on how
tight the PennHip scores were |
|
Short ligament and Shallow Cup |
Poor |
Good |
Good |
Arthritis Less Likely |
|
Short ligament and Deep Cup |
Good |
Good |
Poor |
NORMAL HIPS - NO ARTHRITIS |
|
Short ligament and Deep Cup |
Good |
Good |
Good |
NORMAL HIPS - NO ARTHRITIS |
Questions and Answers:
True or False
Let's see what you know.....
:-)
|
If your dog passes an
OFA with a score of EXCELLENT, he will
never get arthritis? |
False |
|
If your dog has good hips, it should not
matter if he/she is sedated to shoot hip
xrays because it will allow for better
positioning of the hips on the film and
give you a more ACCURATE result.
|
True |
|
OFA prefers that a dog NOT be xrayed
within 6 weeks before, after, or during
a heat cycle |
True |
|
PennHip does not care whether a dog is
in heat when he/she is xrayed and says
that it will not affect the resulting
scores |
True |
|
PennHip xrays cost more because more
films must be shot than with OFA |
True |
|
If you shoot a set of PennHip
radiographs, PennHip does not require
that they be sent in if you can tell
that the hips are going to come back
poor anyway. |
FALSE |
|
If you shoot a set of OFA radiographs,
OFA does not required that they be sent
in if you can tell that the hips are
going to come back poor or dysplastic
anyway. |
True |
|
Positioning of a dog for an OFA film can
alter the OFA results from Good to Fair
or Fair to Dysplastic but are unlikely
to alter the results from Excellent to
Dysplastic |
True |
|
If your dog comes back with a Dysplastic
score in one hip and a Fair in the
other, it is okay to breed as long as
you breed to a mate with very good hip
scores |
False |
|
The older the dog is at the time of the
hip certification, the more accurate the
results |
True |
|
If a dog is xrayed at 2 years of age, he
will never need to be hip xrayed again
because the results will never change. |
False |
Cornell University also has an
interesting article on Hip Dysplasia.......
http://bakerinstitute.vet.cornell.edu/animalhealth/page.php?id=1104\
