Hip Dysplasia
A genetic predisposition is a genetic (unseen) characteristic, which influences the possible phenotypic (seen) development of an individual organism within a species or population under the influence of environmental conditions. “Factors such as excessive growth rate, types of exercise, and improper weight and nutrition can magnify this genetic predisposition”. American Kennel Club (Best Viewed On Desktop)
Our Angus, diagnosed at 10 months, swimming with Kona at the Gulf. After this trip, he was diagnosed with elbow dyplasia as well.
30% Genetic Predisposition
Hip Dysplasia
70% Environment
“Why are so many Labradors STILL being diagnosed with hip dysplasia even though their parents were OFA certified?”
"MY breeder gave me a warranty on my puppy's hips and elbows and I will get my money back if my dog gets dysplasia".
"I would never buy a puppy whose Dam or Sire had a "Fair" hip rating.
I recently was visiting a Labrador Forum where yet another Lab from OFA tested parents had just been diagnosed with dysplasia. Nestled in amongst all the condolences were the quotes you see above. Before our Angus was diagnosed with dysplasia, I might have said the same as that last quote. I know for sure that I thought the same. I had chosen a breeder whose Bitch was certified “Excellent” who had chosen a Stud with an “Excellent” certification. And there was that health warranty. I had done everything possible to ensure that I didn’t have a Labrador who would suffer from HD. Right? The answer is no. The honest answer anyway.
70% Environment
The genetic predisposition is triggered by the environment.
Breeders and Pet Owners alike put far too much faith in subjective, phenotypic testing and health warranties.
I did not provide the proper environment for Angus. I over fed him and over exercised him. I allowed him to play on stairs, jump as often as he wanted, allowed unsupervised play with older dogs with more aggressive play styles.
I allowed the OFA certification of his parents and a breeder's health warranty to give me a false sense of security. Although his breeder honored the Hip warranty and refunded our purchase price, that was little consolation to me as I watched 10 month old Angus struggle while we found the tools to manage his pain.
After Angus was diagnosed we continued to raise Kona, then Dreama with the dream of becoming breeders. While I raised them, I read everything I could find on the subject. I wanted to understand how I could prevent the disorder in not only our own girls, but in any of their future offspring.
Hip Dysplasia is not "inherited" in the way that automatically comes to mind when one reads that word. The reality is that that inheritance is because of traits of the breed itself; in other words, every Labrador has the potential to develop dysplasia and how they are raised will in the majority of cases, determine whether they do or not.
I learned that breeder and owner education provides the most hope in preventing the disorder. This page was created for those who, like me, love a dog that has this debilitating disorder; those who are about to bring home an Aisling puppy; and for other Breeders who want to protect their own offspring.
Traits in the Labrador that predispose the breed to dysplasia
Rate of Growth:
-
The average Labrador weighs about 1 pound at birth; they double their weight by 2 weeks of age and by 8 weeks weigh on average between 12 and 16 pounds. This rapid growth continues until they are about 6 months of age.
-
By 8 months of age, they are nearly at their adult weight which can be anywhere from 65 to 100 pounds and are at about 80% of their adult height.
All parts of the Labrador do NOT grow at the same pace which creates weaknesses in areas that may lead to injury which may lead to issues within the hip joint or elbow - an injury in one leg affects the gait of other legs increasing the odds of joint issues in a second leg.
Temperament:
-
Food Obsession ; lead to over-eating and over-heavy puppies/dogs
-
From 6 weeks of age; Labrador puppies are extremely high energy; much of their awake time is spend running and jumping
-
Bred to face icy waters, the breed has a very high pain tolerance; this, combined with the high rate of energy, can lead to undiagnosed injury and inflammation.
When a Labrador puppy plays, they play full out. When they run, they run full out. This high energy continues until they are at least 2 years of age and with some Labradors, until they are 3 years of age!
Many owners will seek to find outlets for this high energy that are inappropriate for the growing puppy
-
excessive leash walking on hard surfaces like pavement
-
excessive retrieving where the puppy is jumping to catch a ball, stick or frizz bee; activities like agility training where consideration is not given to age appropriate training
-
allowing the puppy jump up on doors, fences, and windowsills, on and off of furniture and in and out of vehicles
Despite decades of searching for a "gene" that would identify which dogs will get dysplasia, one has not been found, nor has any combination of genes been deemed as responsible (there have been reports that STR's and SNP's - in the thousands - have been suspected of causing dysplasia, but as of now, no genetic test is available).
There is currently NO genetic test that can be given to ensure that two Labradors will not ever produce a puppy that will develop dysplasia.
30% Genetic Predispositon & Selective Breeding
Six decades past and then again twenty-two years ago, Breeders were asked to be patient and allow several generations of selective breeding to eliminate canine dysplasia. Journal of the American Veterinary Medical Association 210(10):1474-9 · May 1997
Without a genetic test to rely on, Breeders have participated in phenotypic evaluation based on subjective readings of x-rays to include or eliminate dogs from their breeding program.
Nearly 70 years have passed, choosing our breeding stock based upon the certifications for their hips and elbows has NOT eliminated dysplasia. While OFA Breed Trend reports show an improvement, 12-14% of selectively bred Labradors are still being diagnosed with dysplasia.
Breeders can improve the odds for puppies but cannot prevent the disorder entirely because a determination of "Normal" Hips and "Normal" Elbows by the Orthopedic Foundation for Animals does NOT eliminate the risk for the offspring and along with Breeder Health Warrantees, provide a false sense of security to far too many Labrador owners.
The reason for the continued incidence of dysplasia in selectively bred dogs should be clear - environment plays a much higher part in the condition than previously realized.
Understanding the OFA Rating Method
Preliminary testing is done before the age of two years; the X-ray of hips is read by only one radiologist. Final certification (after the age of two years) is read by three radiologists. NORMAL Hips are rated as Excellent, Good, or Fair but ALL are considered normal. The variance is in slight changes to the joint. BORDERLINE Hips means the dog does NOT have dysplasia but has changes that indicate that it may develop later onset dysplasia / arthritis. DYSPLASTIC Hips are rated as Mild, Moderate, or Severe. The OFA reports that 12% of over 270,000 OFA tested Labradors are “dysplastic”. Once each of the radiologists classifies the hips into one of the 7 phenotypes above, the final hip grade is decided by a consensus of the 3 independent outside evaluations. Examples would be: Two radiologists reported excellent, one good--the final grade would be excellent One radiologist reported excellent, one good, one fair--the final grade would be good One radiologist reported fair, two radiologists reported mild--the final grade would be mild Three Radiologists, all independent and randomly selected to view a particular x-ray, can all see the same X-ray and have different opinions. Re-send the x-ray, and a different set of three radiologists may come to the same or a completely different consensus. The process is far too subjective.
Phenotypic Evaluation Is Just the Starting Point
12 - 14% of over 270,000 selectively bred Labradors are rated as "dysplastic"; dysplastic hips are rated as Mild, Moderate, or Severe. (Note that at the time of this paper, OFA did not breakdown the percentage among these ratings on the Breed Trends Report). A little information before we dig into this! Genotype/unseen. Most health testing done by breeders today is genetic (via swabs of DNA). Phenotype/seen. Hips and Elbows are phenotypic testing based only on what is visible at the time of testing. Selectively Bred: Dogs bred from parents who have been certified with "normal" hips and elbows. After more than 60 years (30 generations on a dog's pedigree) of selectively breeding OFA certified dogs Dysplasia has not been eliminated as promised if we removed even "fair" and "borderline" dogs from our breeding programs. 12 - 14% of over 270,000 selectively bred Labradors are rated as "dysplastic"; Hips are rated as Mild, Moderate, or Severe. (Note that at the time of this paper, OFA did not breakdown the percentage among these ratings on the Breed Trends Report). 19% of selectively bred Labradors are rated as "Excellent" 67% of selectively bred Labradors tested by the OFA are "GOOD" "FAIR" or "BORDERLINE" (Again, note that at the time of this paper, OFA did not breakdown the percentages among these ratings. One must wonder if it because the normal state of a two year old Labradors hips is actually "borderline".) Even dogs certified as "Excellent" at two years of age may STILL develop late onset dysplasia. "Pet population" Definition: The pet population consists of those dogs not selected for a breeding program who are never phenotypically evaluated for dysplasia and those who are due to lameness whose results will never be sent to the OFA. The Pet Population is grossly under represented in the OFA Database where 12%- 14% of selectively bred Labradors are still rated with varying degrees of dysplasia. OFA TRENDS REPORT FOR LABRADOR RETRIEVERS A bit more: The Founder of the OFA, the man who initially believed that phenotypic testing of breeding dogs would eliminate dysplasia resigned when he realized that this was not happening. Regardless, the OFA continues to set the criteria for choosing our breeding dogs. Originally, the OFA certified hips at 18 months but when selectively bred dogs were still being diagnosed with dysplasia, they changed certification age to two years. The next step was to divide the "Normal" results into three categories in an attempt to show improvement beyond what Breeders were promised. Continually moving the goalpost has not eliminated dysplasia because - as studies are proving - it is not "inherited" from parent to child as much as it is a genetic predisposition shared by all medium and large breeds based upon structural and temperamental TRAITS of the breeds themselves. Breeders, despite doing all they were asked to do, are still liable for offspring that were crippled by the disorder despite the fact that we only control the environment for the first 8 weeks of a puppy's lifetime.
Controlling the Environmental factors that may trigger dysplasia
Environmental studies show that there is a correlation to the surface during the first 8 weeks of a puppy's life and future hip and elbow health. In fact, it does appear that the first THREE months of life have a greater impact on future joint health than any other factor. This means that the first four weeks your puppy is in YOUR home is as important as the phenotypic evaluation for parents, grands, and greats and the first eight weeks in the Breeder's home.
Estimated heritability of an average of 30%
"Hip dysplasia (HD) in dogs is affected to a larger degree than previously believed by the environment in which puppies grow up. It is particularly during the period from birth to three months that various environmental factors appear to influence the development of this disease. During the puppy stage, preventive measures can therefore be recommended with a view to giving dogs disposed to the condition a better quality of life. Dogs are not born with HD, but genetically disposed puppies can develop varying degrees of HD.”
Labrador Retriever ranked 113th in Breeds with dysplasia ALL DATA: Tests 304,077 (previous 270,00); 87.3% Rated Normal (Excellent, Good, Fair)/previously only reported "Excellent" status at 19%); 11.6% Dysplastic (Severe, Moderate, Mild/previously 12 -14%) remains the most tested breed in the database.
"If your growing puppy is a larger (or immense) breed such as a Great Dane or Newfoundland, and you’re searching for a product in that “Growth and Reproductive” stage, make sure the food has a statement asserting that it meets the nutritional needs of “large-size dogs (70 lbs or more as an adult dog).”
Most of the estimates of heritability of hip dysplasia score in dogs are in the range of 0.2-0.3, which means that 20-30% of the variation you see among dogs in hip scores is accounted for by genetics - and it also means that 70-80% of the variation is from environmental causes, many of which breeders and owners can control.
Hip dysplasia (HD) and elbow arthrosis (EA) are, despite extensive breeding programs, still causing problems in many dog breeds such as the Labrador Retriever.
The #1 and #2 common injury factors for puppies - it's not just about hips and elbows
"In contrast to European countries, the overwhelming majority of dogs in the U.S. are neutered (including spaying), usually done before one year of age. Given the importance of gonadal hormones in growth and development, this cultural contrast invites an analysis of the multiple organ systems that may be adversely affected by neutering. "
Although there is a genetic influence on hip dysplasia, the heritability of the trait is rather low. Many studies have shown that genetic variation accounts for only a modest fraction of the variation in hip scores, usually 15-40%. (Breed dependent which accounts for the range)
"However, conformational characteristics and environmental factors such as diet and exercise are thought to have profound effects on the phenotypic expression of DJD in individuals genotypically predisposed to hip dysplasia."
"Calcium and phosphorus work together, and a proper calcium-to-phosphorus ratio is essential for healthy bones and joints. The calcium: phosphorus ratios in your pup’s diet should be between 1.1:1 and 1.3:1."
It is particularly during the period from birth to three months that various environmental factors appear to influence the development of this disease. During the puppy stage, preventive measures can therefore be recommended with a view to giving dogs disposed to the condition a better quality of life."