It’s no secret that hip dysplasia (HD) is a common serious problem for working dogs, especially the larger ones like our LGDs. It’s truly not a secret, but given the way that some breeders are reluctant to discuss it, it can certainly feel that way. One of the reasons for this reluctance is that there have been very few concrete answers about the prevention of HD. It is a polygenic (informed by multiple genes) disorder that is highly influenced by environment and care and may also be epigenetic in nature – complicated, to say the least. If you’re not familiar with the term ‘epigenetic’, here is a good run down on what it means for our canine partners.
Before we get too far into what’s behind HD, let’s take a little look at why we should be considering HD in our LGDs.
Canine Hip Dysplasia was first described in 1937 by Dr. Gary Schnelle. At the time it was assumed to be rare, but not quite 80 years later is the most common inherited joint disorder in dogs as well as the leading cause of arthritis of the hip. It affects up to 50% of some registry breeds and disproportionately affects large purebred and mixed breed dogs.
Here are some illustrations and a radiograph of what HD looks like.
A healthy hip has a ball and socket construction. The ball sits at the top of the femur and is nicely rounded. It fits snugly into the socket in the side of the hip, one on each side. If you ball up your right hand into a fist, cup your left hand like a semi circle or “C”, then place your right hand into your left, you’ll get a fairly good idea of what this looks like. You can move your right hand around in the cup of your left hand to replicate the movement of the ball in the hip socket. In the joiny, of course, there is a lot more to it – ligaments to hold the ball in place, cartilage and synovial fluid to cushion and lubricate the joint motion, etc.
The failure of any of these parts is detrimental to the hip joint, but nothing quite as destructive as a malformed ball and socket. Instead of sliding smoothly in motion, the bones grind and rub against each other, causing the bony spurs to grow that can be quite painful. As the disorder progresses, osteoarthritis sets in. The affected dog will have difficulty raising and lowering their body and will be stiff after periods of rest and during climate changes.
There are degrees of malformation with HD and a variable rate of onset, although 95% of dogs will be diagnosable (via x-ray) by 24 months of age. All pups are born with normal hips but within months or years begin to show visible signs associated with joint laxity (looseness). The most common symptoms are as follows:
- decreased activity
- exercise intolerance
- reluctance to rise. sit/lie, run or climb stairs
- “wobbly”, swaying gait
- pain, tender to the touch
- “bunny hopping” with the back leg(s), especially when running
- increased muscle mass in the front shoulders due to over compensation carrying body weight
- grating sound on motion of the hip
- arthritic signs as the condition progresses
Since this is a disorder that presents on a spectrum (meaning that there are milder forms, moderate and severe forms), not all dogs experience a lot of pain, especially if arthritis has not yet set in. For this reason, an owner’s reliance on observation to diagnose HD can’t be trusted. Some dogs with severe changes on x-ray show little pain or reluctance to move, whereas some with mild changes are quite lame. The correlations are still poorly understood.
Apart from the fact that living with any of the above symptoms will negatively impact the ability of the working LGD to fulfill their role as guardian, the stress of living with such complications will shorten their working life. It is a well known fact that arthritis causes chronic pain, which in turn can cause heightened anxiety and irritability, interfering with the thoughtful process necessary to guard livestock. It also causes chronic stress which contributes to a shortened life span. Given the stoic nature of our LGDs, it could take some careful body language interpretation to deduce. Some dogs are able to behave very close to normal most of the time, but their tolerance for anything out of the ordinary is greatly compromised. This is often the cause of “out of the blue” type aggressive behavior towards trusted people or animals. In the worst case scenarios, the dog becomes unable to rise or carry out their duties at all far before old age sets in and often has to be euthanized.
Pregnancy can increase the rate at which HD progresses in the bitch, as outlined in this informational post by Rachel Counts. It can leave her unable to rise or walk without extreme discomfort, compromising both her health and that of her pups. Birthing is very difficult on the bitch’s hips and can exacerbate the problem further. If a bitch is intended to work during her gestation, ensuring that she is free from HD will make her much more likely to comply. Canine hip dysplasia has also been determined to be in part hereditary. As such, if one or both of the parents has the condition, it is much more likely that a significant portion of the pups will as well.
So what does all of this mean? PennHIP, which along with OFFA screens and rates radiographs for HD puts it best:
“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.”
Today, the general veterinary consensus is that hip dysplasia is a heritable disease manifested as hip joint laxity that leads to the development of OA.
Canine Hip Dysplasia afflicts millions of dogs each year and can result in debilitating orthopedic disease of the hip. Many dogs will suffer from osteoarthritis, pain, and lameness, costing owners and breeders millions of dollars in veterinary care, shortened work longevity, and reduced performance. The occurrence of CHD is well documented in the large and giant breed dogs, but there is also evidence that CHD is prevalent in many small and toy breeds as well as in cats.”
Stay tuned for the second part of this discussion on hip dysplasia, up next.
Orthopedic Foundation For Animals: http://www.offa.org/hd_info.html
Baker Institute, Cornell University: http://bakerinstitute.vet.cornell.edu/contentimages/library/File/Canine_Hip_Dysplasia_brochure_11_05.pdf
Veterinary Referral Surgical Practice: http://veterinaryreferralsurgery.com/article_dysplasia.php