Puppies are hip!
Our previous article shows that puppies are born with perfectly, normal hips. Puppy hips are quite amazing, although they are not quite adult hips yet.
Looking at their x-ray, a newborn puppy looks like it has no joints at. This is due to the ends of the long bones and many parts of the pelvis being soft cartilage at birth. Cartilage doesn’t show up on x-rays. A new newborn puppy’s x-ray may appear like a disarticulated body. However, mother nature knows what she is doing. She provides just enough support to help your puppy move around while his skeleton grows – and it grows quite fast in the first few months.
At birth, the hip joints are also formed of cartilage. The hip joint appears as a little round ball at the end of the femur that sits in a “dent” in the pelvis. This “dent” is where the hip socket will be.
As your puppy grows, the bones that later form the hip joints are not all programmed by genes. Rather, forces placed on the joint stimulate the placement of growing bone cells in the all the right places. This forms the articulating ball and socket or hip joint.
“As long as the head of the femur (thighbone) stays seated where it belongs in the developing hip socket, the hip joint should form perfectly.”
~ Carol Beuchat PhD
This seems so easy and almost too good to be true. There is a small catch.
If the head of the femur (long bone) is not kept snugly in the hip socket, the development and formation of the joint go out of kilter. The result: “developmental hip dysplasia”; malformation of the hip socket. What veterinarians will call canine hip dysplasia.
“In all mammalian embryos, the hip is laid down as a single unit from mesenchymal tissue (connective tissue that develops the musculoskeletal system) and it develops normally as long as the components are left in full congruity. The hip is normal at some time in the development of the mammal, and abnormal development occurs only when stresses pull the components apart.
In the dog, the hip is normal at birth. Intrauterine (development within the womb) stresses are not sufficient to produce incongruity of the hip. The first time such forces are great enough is when the pup begins to take its position to nurse.
Observations of the disease in man, dog, and a number of other mammals for many years have culminated in the conviction that the bony changes of hip dysplasia, regardless of species, occur because the soft tissues do not have sufficient strength to maintain congruity between the articular surfaces of the femoral head and the acetabulum.”
~ Wayne Riser, founder and first director of the Orthopedic Foundation for Animals (OFA)
What does this mean?
Simplified, it means that muscles, ligaments, and tendons (“soft tissues”) normally keep the head of the femur snugly fitted in the developing socket. If abnormal forces are placed on the joint, these soft tissues might not be enough to stabilise the joint. Malformation of the socket – hip dysplasia – will then occur.
As Riser described, looseness/laxity of the hip joint causes the femoral head to not fit snugly into the hip socket. Joint looseness may then be a prerequisite triggering the development of hip dysplasia.
As puppies grow, there are mechanical forces placed on the joints – i.e weight bearing forces when walking, running, playing.
If the head of the femur (thigh bone) is not positioned properly in the hip socket (i.e. it fits only loosely) during a puppy’s growing months, the mechanical forces that stimulate a natural process of laying down bone in the joint will be abnormally dispersed and the result will be a dysplastic hip.
Greyhounds very rarely suffer from hip dysplasia. Their muscles supporting the hip are exceptionally well developed. This includes their good development of pelvic muscles.
Strong pelvic muscles provided exceptional hip stability within the Greyhound breed. Newborn Greyhounds also demonstrate strong pelvic muscles.
Unfortunately, most breeds of dogs don’t have the strong pelvic muscles of the Greyhound at birth. These strong pelvic muscles are required for the speeds that Greyhounds achieve.
Some dogs are bred for size and strength such as drafting or carting dogs such as the Bernese Mountain Dog.
Structural differences in breeds tend to reflect their predisposition to develop hip dysplasia.
Factors causing hip laxity resulting in the development of dysplasia occur in the first few months of the puppy’s life.
Sometime between birth and four or five months old, a puppy’s soft tissues of the pelvis don’t provide enough support to keep the femoral head snug and tight in the hip socket.
During this time is when the cartilaginous tissues of the hip joint are able to become a perfectly constructed ball and socket joint.
Loose joints result in any uneven forces to become exaggerated. This means that normal forces placed on the joint through movements such as playing, running along with other environmental factors such as weight and inappropriate exercise begin the cycle of damage and inflammation sooner. The joint then cannot develop properly. The result is dysplasia and osteoarthritis.
Both in children and dogs, hip dysplasia is, for the most part, a ‘man-made’ problem and can be controlled if man will use the tools at his disposal.
Few genes so far analyzed directly affect osseous structures. [This is still true.] The shape of bones reflects changes by biomechanical stresses.
~ Wayne Riser
Growing puppies too fast or breeding puppies too big for its breed standard in any breed will set back efforts to produce dogs with better hips.
Similarly, poor weight management in puppies and adults dramatically increases the risk of developing dysplastic hips.
It is always important to grow your puppy slowly.
Finally, we should use that rare talent, a little common sense, about activities that are appropriate for puppies.
This apparently common activity that is the worst for your puppy’s developing hips. It should go without saying, but apparently not…
Many think this type of video is “just toooo cute!” – please think again!
~ Carol Beuchat PhD – Excerpts from her article “How do hips become dysplasic” in Institute of Canine Biology