Radiographs

PennHIP Radiographs – improving hip dysplasia diagnosis

Posted on in Dog Hip Dysplasia, Radiographs Comments Off on PennHIP Radiographs – improving hip dysplasia diagnosis

Diagnosing Canine hip dysplasia using PennHIP

 

Canine hip dysplasia is a well recognized genetic condition in dogs that can cause hip arthritis, chronic pain, and sometimes requires surgery. Over the last fifty years, breed organizations and kennel clubs have attempted to remove the disease from the population through selective breeding. Despite this effort, little progress has been made. This may be in part due to the under utilization of the PennHIP radiographic technique.

Normal dog with hip joints PennHIP compressed

Normal dog with hip joints PennHIP compressed

 

 

OFA (Orthopedic Foundation for Animals) Radiographs

Selecting dogs that are considered “hip dysplasia free”, those considered unlikely to pass the condition onto their offspring, has largely been based on their OFA radiograph findings – by x-raying the appearance of the hips while the dog is lying on its back with its legs in full extension.  Unfortunately, research has shown that OFA radiographs are a poor test for screening against hip dysplasia.

OFA radiographs are a poor test because although they select for dogs with good hip conformation, they does not test for soft tissue laxity, a key component in the development of hip dysplasia. As a result, many dogs that pass their OFA radiographs have now been shown to have lax hips This is likely the reason that efforts to eliminate the disease have not worked. Research has found that breeding dogs with passing OFA radiographs results in hip dysplasia in anywhere from 19% to 73% of the offspring.

PennHIP (Pennsylvania Hip Improvement Program) Radiographs

PennHIP radiographic testing was introduced over 20 years ago, and tests both hip conformation (as does OFA) as well as tissue laxity. It is a more sensitive test than OFA radiographs, meaning that it will detect cases of hip dysplasia that otherwise would be missed. In order to breed hip dysplasia out of the gene pool, it is key that all dogs potentially carrying the condition are detected, and therefore the test needs to be as sensitive as possible.

 

Normal dog with hip joints PennHIP distracted - the joint space has been highlighted blue. Notice how little difference there is between the hip compression and distraction view. This indicates a stable hip joint.

Normal dog with hip joints PennHIP distracted – the joint space has been highlighted blue. Notice how little difference there is between the hip compression and distraction view. This indicates a stable hip joint.

Which is better?

Side by side comparison of OFA and PennHIP radiographs found that none of the dogs that failed their PennHIP radiographs, passed their OFA radiographs, but many dogs that passed their OFA radiographs, failed their PennHIP radiographs. In fact, two of the dogs with “excellent” OFA ratings had some of the worst PennHIP scores, indicating a high probability of developing hip arthritis secondary to tissue laxity later in life.

Another limitation of OFA radiographs is that scoring is based on subjective evaluation. This means that the same radiographs may get a different score depending on who is reviewing them, or even if the same radiologist reviews them on different days (with a different mood, fatigue level etc.). This problem is reduced with PennHIP radiographs because the results are based on measurements and the calculation of a distraction index, which is less likely to show variation between radiologists.

OFA radiographs require the dog to be at least 2 years of age before testing, whereas PennHIP radiographs have been shown to be accurate in predicting the onset of hip dysplasia as early as 4 months of age, allowing for earlier testing.

Conservative estimates based on mathematical models indicate that for a breeder of Labrador retrievers hoping to eliminate hip dysplasia from their line, using the PennHIP system will accomplish that goal 4 times faster than by relying on OFA radiographs.

Although some dogs receiving OFA radiographs may not need sedation, sedation is mandatory for PennHIP radiographs in order to relax the muscles enough to properly appreciate the degree of connective tissue laxity.

Hip dysplasia PennHIP compression view - notice how the dog's left hip joint space (right side of picture) has an irregular width

Hip dysplasia PennHIP compression view -notice how the dog’s left hip joint space (right side of picture) has an irregular width

 

Who should Consider PennHIP?

Any breeder who is serious about producing a line of dogs free from hip dysplasia should employ a PennHIP screening program. Pet owners and dog handlers who want to invest in a dog suited to an active life style, working, or competition, should also consider only purchasing PennHIP cleared dogs. Dogs can be tested for hip dysplasia using the PennHIP method as early as 4 months of age.

If you have any further questions about PennHIP testing in BC, please email info@pointseastwest.com

 

Hip dysplasia distraction view - notice how much wider the joint becomes once it is distracted, compared to the normal dog.

Hip dysplasia PennHIP distraction view – notice how much wider the joint becomes once it is distracted, compared to the normal dog.


Case Report: Bode the SPCA dog’s tarsal arthrodesis

Posted on in Broken bone, Case Reports, Radiographs 3 Comments

Case Report: Bode the SPCA dog’s tarsal arthrodesis

 

Bode cast4

Bode sporting a dapper blue collar with matching leash and cast.
Photo Credit: Soundingsoul Photography

 

Bode is a sweet dog. He was turned over to the SPCA after it was learned that he had been limping around on a dislocated tarsus (ankle) for over a month.  His story spread across social media, with people from all over donating money to his cause.

 

 

Together with donations from local veterinary teams, he was able to undergo the treatment he needed – first to address his infected wound and painful abscessing teeth, then to fix the tarsus itself.

SPCA Bode luxated tarsus AP

Front view of dislocated tarsus.

 

 

 

 

 

Because the tarsus had been dislocated for so long, the joint cartilage was dead.  That meant there was no hope of saving the joint without leaving Bode a legacy of chronic arthritis and ongoing pain.  Instead, the decision was made to perform a tarsal arthrodesis, or to fuse the joint.  It would mean that Bode would always have a hitch when he walked, but that he would also be forever pain free in that joint.

SPCA Bode tarsal luxation lat view

Side view of dislocated tarsus.

 

 

 

 

 

 

 

 

 

 

 

 

 

These radiographs were taken when Bode was first diagnosed. The first one is a front view, and the second one is a side view of the dislocated tarsus.

 

 

SPCA Bode luxated tarsus AP graphics

Front view of dislocated tarsus (ankle) with coloured lines to show how the joint surfaces should be lining up.

 

 

 

 

 

 

 

 

 

For clarity, I’ve added fancy graphics.  These are the same two radiographs, but with the joint surfaces highlighted.  The red line traces along the end of the tibia, and the green line traces the joint surface of the talus, one of the ankle bones.

 

The first part of the surgery involved breaking down the extensive scar tissue that had formed after a month of no treatment.  Only then could the two bones be put back together.  Once that was completed, a fair amount of bone and scar tissue had to be chiselled from the tibia to make a flat surface.  It is along this surface that the stabilizing implant would be placed.

Side view of dislocated tarsus (ankle) with coloured lines to show how the joint surfaces should be lining up.

Side view of dislocated tarsus (ankle) with coloured lines to show how the joint surfaces should be lining up.

 

 

 

 

 

 

 

 

 

Once that was done, all the joint cartilage was removed and small holes were drilled into the underlying bone to stimulate repair.  A hole was also drilled in the top of the tibia and a cancellous bone graft was collected – a harvest of marrow rich in the cells needed to grow new bone – and placed in the joint spaces.  Once that was complete, the stabilizing metal implant was applied.

 

 

Side view taken immediately after tarsal arthrodesis surgery showing application of a specially designed plate for tarsal arthodesis.

Side view taken immediately after tarsal arthrodesis surgery showing application of a specially designed plate for tarsal arthodesis.

 

 

 

 

 

 

 

 

This radiograph was taken immediately after surgery.  It is a side view with a special “banana plate” applied to the tarsus with nine screws.  If you look at the top of the tibia, you can see the hole through which the bone graft was collected.

Post surgical side view of tarsal arthrodesis with graphics higlighting old joint space and bone graft collection site.

Post surgical side view of tarsal arthrodesis with graphics higlighting old joint space and bone graft collection site.

 

 

 

 

 

 

Here is the same radiograph again with more fancy graphics – the purple area represents where the remnants of the old joint space used to be.  The cancellous bone graft selection site is highlighted in red

For the next 8 weeks, Bode moved into the house of an SPCA representative.  He wore a cast to support the implant while healing began and was under strict exercise restriction.

Side view of tarsal arthrodesis taken 8 weeks after surgery.

Side view of tarsal arthrodesis taken 8 weeks after surgery.

 

 

These last two radiographs were taken approximately eight weeks after arthrodesis surgery, and show good healing.  The joint space is no longer visible.  The healing bone is not yet at full strength, but it has starting to share some of the work so Bode no longer needs a cast.  He is still restricted to leash walks, and isn’t out of the woods yet, but he is on his way to a full recovery.

Front view of tarsal arthrodesis taken 8 weeks after surgery.

Front view of tarsal arthrodesis taken 8 weeks after surgery.

 

 

 

 

 

 

The muscles in Bode’s leg are very weak and severely atrophied, so he has been prescribed a comprehensive rehabilitation program to speed his recovery.  It will teach him that he can use the leg without pain, build muscle mass, and speed his return to an active lifestyle.

Thank-you to all those who stepped up to help this wonderful dog.

 

 


Radiograph Abnormality

Posted on in Radiographs 3 Comments

Can you identify the radiograph abnormality:

What is your diagnosis?

hemivert bottle cap

Radiograph abnormality answer:

This dog has an abnormally short 7th lumbar vertebra.  Notice how much smaller the furthest vertebra on the right is when compared to it’s neighbours.  This is a genetic issue he was born with, and is more common in pugs, boston terriers, bulldogs etc.  There is also some degeneration of the lumbosacral joint.

Also, for some reason, this dog has been throwing up a lot.