Hip Dysplasia - A Mini-Tutorial for the Puppy Buyer
This tutorial is intended to give the Puppy Buyer a better understanding of what Hip Dysplasia means, the terminology they may encounter, and things they can do to prevent Hip Dysplasia in their new puppy.
What Is Hip Dysplasia?
Hip Dysplasia (HD), refers to an abnormal anatomic structure of the hip joint. The hip joint is a ball (top part of the thigh bone) and socket (pelvis) joint, held together by the fit of the bones, ligaments, and muscles. Abnormal development of the hip joint is characterized by laxity (looseness) that leads to abnormal wear of the joint, which can lead to osteoarthritic changes and pain.
A Mini-Tutorial for the Puppy Buyer
What Causes Hip Dysplasia?
Heredity plays a major factor in how the bones, muscles, and ligaments are destined to develop. Other factors, such as diet, exercise, growth rate, and weight will be discussed in the Prevention section (below).
First and foremost, select a puppy from a Breeder that screens their breeding dogs for HD. The theory is that breeding dogs with healthy hips are more likely to produce offspring with healthy hips. While it is not a guarantee against HD, it does improve the odds. It is safe to say that parent dogs with HD are likely to produce puppies with HD. See also the Testing section (below).
I already have a puppy, what can I do now?
While you can't change your puppy's parents, or its genetic makeup that may or may not include Hip Dysplasia, you can give your puppy the best possible environment to help delay or minimize the effects of this disease. This is done by slowing the growth rate of the puppy, maintaining a healthy weight (not too fat), and using exercise wisely to build muscle mass.
Diet: A high fat, high protein diet can lead to growth spurts in young pups that put a strain on the developing joints. Because of this, there are puppy foods developed for the “Large Breed Puppy”. Some Veterinarians will also recommend switching your puppy over to Adult food at a young age to slow the growth rate. Read the package labels for protein and fat percentages and compare the various choices available. If your puppy is meant to be a big dog, it will still be a big dog even though you've slowed its growth. It will just be more likely to be a healthier big dog than one that grew too fast.
Certain supplements may help in managing hip health. Glucosamine is one supplement that is sometimes found in Large Breed dog foods, and can be purchased as a separate supplement as well. Ester C, a form of Vitamin C, is thought by some to alleviate pain in dogs with HD. It is also generally accepted that high levels of Calcium in the diet are problematic, and supplementing the diet with additional Calcium should be avoided. Work with your Veterinary professional to determine an appropriate treatment plan.
Weight: Being overweight puts undue strain on joints such as the hips. A dog which is lean is better off in this regard than one that is even slightly overweight. Regularly monitor your pup's weight. This can most easily be done by feeling the pup's ribs. You should always be able to feel a dog's ribs under their coat. Ask your Vet to show you how to do this if you are in the least bit unsure.
Exercise: Puppies, like babies, should receive age-appropriate exercise. They should be allowed to play or stop playing at will. They should not be encouraged to walk or run long distances or for long periods of time. Excessive leash walking, for example, can cause repetitive stress injuries to their developing joints and muscles. Excessive leash walking would be similar to walking on a treadmill, and should not be confused with the leisurely stroll taking time to smell the flowers. There is a huge difference between a puppy sprinting around the yard, stopping, and resuming play at will, and one who is kept moving at a consistent pace for the same period of time.
It is generally accepted that you should not jog with your dog until it is at least a year old, and then it should be kept in mind that their stamina needs to be built up over time.
Until they develop strength and good coordination, the risk of falling off stairs, or other high places, should be avoided.
Finally, the risk of repetitive stress injury to a puppy's growing body is a concern in the most general of senses. All joints, bones, muscles, ligaments, are at risk of injury if a pup is encouraged or forced to repeat the same motion over and over for an extended period of time. This can include, but is not limited to, long walks at a constant pace, trotting for long distances, excessive stair or hill climbing. If done in moderation, these things can be safe and beneficial; if taken to excess, it has the potential to damage their growing bodies. Your puppy needs exercise to develop properly, just remember they are babies at 9 weeks, and only young adults at one year, scale their exercise to their developmental stage.
Another thing the pet owner can do, is take the opportunity to have their pup's hips X-Rayed, preferably by a radiologist, during another procedure requiring anethesia. This could be at the time you have your pup spayed / neutered, or at some other time, such as a dental cleaning. The traditional “Hip Extended View” is appropriate for this type of information.
Testing before Breeding
What you need to know
What your pup's Breeder can do to give your puppy the best chance at good hip health is to test their breeding dogs and only breed dogs with healthy hips.
Do not expect your puppy to have been tested before you purchase them, as none of the currently available tests are valid for puppies under the age of 4 months.
The science of detecting Hip Dysplasia in dogs is still in its infancy. Because Hip Dysplasia is a complex disease, involving the development of the bones of the hip joints, ligaments and muscles, there is no simple genetic blood test to identify dogs with the disease. The only tools currently available involve examination of the conformation (shape) and condition of the hip joint via X-ray. The methods for analyzing the X-rays vary somewhat from organization to organization, but essentially they are all looking for two basic things: evidence of laxity (looseness / poor fit) and evidence of remodeling of the joint due to osteoarthritic changes. All of the various testing organizations then use their own grading scale to quantify their findings.
This section will attempt to give you a brief understanding of some of the various testing organizations, and their grading scales. It should be noted that almost every country seems to have its own testing organization, and the list would be overwhelming if all were included. Therefore, this article is limited to the organizations most likely to be used by Doodle Breeders in North America. See also the Terminology section.
The BVA, OFA, and OVC systems all use one X-ray view of the dog's hips, called the “Hip Extended” view. From this single X-ray view, they determine the fit of the joint, and whether or not any osteoarthritic changes are present (one indication of Dysplasia). All of these methods are sometimes referred to as being subjective.
BVA assigns a number to each hip, and the dog's score is the sum of the two hips. BVA scores are compared with the OFA scoring system on the OFA website at: http://www.offa.org/hipgrade.html
OFA assigns a grade of: Normal (“Excellent”, “Good”, “Fair”), “Borderline” and Dysplastic (“Mild”, “Moderate”, “Severe”). OFA scores are considered “preliminary” if the dog is under 2 years of age, and the official score can only be obtained from tests run after age 2 years. Along with an official score, a tracking number is assigned by OFA for those dogs that are in the normal range (Excellent, Good, Fair). There is a tendency for the score to change between preliminary and official scores, which is why OFA does not assign an OFA number to a preliminary score. If there is a change in score from preliminary to official, it is generally worse, not better, e.g. an OFA preliminary "good" at 6 months of age can change to an OFA "fair" when the official score is obtained after age 2 years.
OFA has an open and online database where the dog's results can be looked up by the official number. It is optional for this information to be made public, hence, not all dogs that have OFA numbers assigned will be found there. OFA also assesses, scores and assigns numbers in their database for other portions of a dog's anatomy (Elbows, Patellas, etc.). So, even though most people might mean hip scoring when they say a dog has been OFA'd, it is best to confirm that is actually what they mean.
OVC assigns either “Normal” or “Dysplastic” scores to dogs over 18 months of age. OVC does not currently have a website explaining their criteria, although they assured us that they are working on one.
PennHIP represents the newest testing method. Use of the PennHIP method is growing in popularity and, with that, availability of the test is expanding worldwide. Currently it isn't available everywhere, so some Breeders are forced to use one of the other systems. PennHIP is generally accepted as being an objective test. The PennHIP system uses the “Hip Extended” view, as well as two additional X-rays (Compression and Distraction), to measure the looseness of the hip joint. The score assigned to the results is what is called a “Distraction Index” (DI), a measurement of the range of motion in the joint itself, and is a number between 0.00 and 1.00, where the tightest joint is 0.00, and the loosest is 1.00. For each breed of dog in the PennHIP database, they calculate the “Breed Average”, the average score of all the dogs, and their report gives the DI number as well as a comparison to other dogs of that breed. Because the “Breed Average” changes as more dogs are tested, it is not possible to give a specific number that corresponds to the normal hip or even the average, but know that a score of 0.30 corresponds to very tight (healthy) hips for any breed of dog, and a score 0.70 corresponds to very loose hips. The difficulty in comparing this method to the other methods is that most dogs are somewhere in between 0.30 and 0.70. The minimum age for PennHIP is 4 months.
Diagram showing the positioning used for the PennHIP Compression and Distraction X-Rays:
Finally, be wary of anyone who tells you that their breeding dogs' test scores are "Pending". The time between taking X-Rays and getting Hip Score results, regardless of testing organization, is far less than the time it takes to whelp a litter. Use of this term indicates that they might not have tested prior to breeding, and could be considered a warning sign.
Arthritis - Inflammation of a joint.
BVA - British Veterinary Association (UK/Australia). BVA also refers to the hip scoring system of that organization.
Dysplasia - Abnormal anatomic structure due to abnormal growth or development.
OFA - Orthopedic Foundation for Animals (USA). OFA also refers to the hip scoring system of that organization.
Osteoarthritis - Degenerative arthritic changes to cartilage and bone in a joint. It is commonly referred to as the “wear and tear” form of arthritis.
OVC - Ontario Veterinary College (Canada). OVC also refers to the hip scoring system of that organization.
PennHIP - University of Pennsylvania Hip Improvement Project. PennHIP also refers to the hip scoring system of that organization.