12 28/2020  How hips form and Wolff's Law
12/27/2020  The basics of hip dysplasia in dogs
    1/3/2020  Do your puppies have enough traction in the whelping box÷
  8/23/2019  Why do mixed breed dogs have so many mutations?
  8/15/2019  About pithy statements vs knowledge
    7/9/2019  Let's kill the breeder myths!
    7/5/2019  What is "heritability" and why do you need to know?
  6/17/2019  Facts vs fear mongering
  4/29/2019  Is health problem X in my breed caused by inbreeding and/or loss of genetic diversity?
  4/19/2019  No, we have NOT found the mutation that causes breathing problems in brachycephalic dogs
  4/21/2019  An update on hip dysplasia in dogs
​  4/20/2019  Addison's Disease and those doggone DLAs
​  3/26/2019  Genetic rescue and rehabilitation: I. Restoring genetic diversity of a breed
  3/12/2019  The key requirement for preservation breeding
  2/28/2019  The genetics of canine behavior goes molecular
  2/14/2019  The messy science of assessing working ability in dogs
    2/5/2019  A new ICB course that will use the DNA data from YOUR dog!
  1/20/2019  How to breed dogs that are better than their parents: the genetics of continuous traits    
    1/7/2019  The right - and wrong - way to use DNA tests
​    1/6/2019  Are breeding restrictions putting your breed at risk?
12/31/2018  More on "Simple strategies to reduce genetic disorders in dogs"
12/29/2018  Simple strategies to reduce genetic disorders in dogs
12/24/2018  Celebrating the preservation breeder!
11/27/2018  On preserving the purebred dog.
11/23/2018  Is the Ky allele in Wirehaired Pointing Griffons evidence of cross-breeding?
    9/7/2018  Cool tricks with Kinship Coefficients, part 4: How closely related are the dogs in my breed?"
    9/6/2018  Cool tricks with Kinship Coefficients, part 3: "How can I manage a disease without a DNA test?"
    9/4/2018  Cool tricks with Kinship Coefficients, part 2: "Should I breed this dog?"
    9/4/2018  Cool tricks with Kinship Coefficients, part 1: "Is this dog really an outcross?"
  8/22/2018  The easy way to understand inheritance of recessive alleles
  8/10/2018  The amazing secrets hiding in your pedigree database
  7/21/2018  We can reduce the risk of hip dysplasia NOW!
  7/12/2018  Is BetterBred better?
    7/7/2018  Assessing genetic diversity and relatedness in dogs using DNA
  6/30/2018  Using genomics to manage genetic disease. You don't need to find the genes
  6/28/2018  How much does outcrossing improve genetic diversity?
  6/26/2018  Are you improving genetic diversity, or just pushing the peas around?
​  6/25/2018  NEW: ICB Genetic Management Workshops
  6/21/2018  A DNA Primer for Dog Breeders. Genetic Diversity: Inbreeding (Fis)
  6/21/2018  A DNA Primer for Dog Breeders. Genetic Diversity: Inbreeding (ROH)
  6/21/2018  A DNA Primer for Dog Breeders. Genetic Diversity: Heterozygosity
  6/21/2018  A DNA Primer for Dog Breeders. ICB Breeder Tool Quick Start Guide
​  6/21/2018  A DNA Primer for Dog Breeders (You have your dog's DNA data. Now what?)
  6/17/2018  No pedigree? No problem!
  5/31/2018  A key innovation in dogs: diet
​    5/1/2018  The lesson(s) from SOD1and degenerative myelopathy
10/27/2017  Update on Newfoundlands
10/26/2017  Please don't ruin the Newfoundland
  8/26/2017  The amazing dog nose: can you smell me now?
​  8/24/2017  The complexity of cancer
  8/12/2017  Are preservation breeders preserving the Doberman? (No.)
    8/5/2017  Hip laxity and the risk of degenerative joint disease
    8/2/2017  Making better decisions about hip and elbow dysplasia: the era of genomics is here
  4/29/2017  New insights into the development of dog breeds
  4/27/2017  The genetic status of the Bernese Mountain Dog
    4/3/2017  How to win The Health Test Game
  3/12/2017  An update on the genetic status of the Doberman Pinscher
    3/9/2017  Lessons from wolves
​    3/6/2017  Why "vulnerable breeds" are vulnerable
​    3/3/2017  Inbreeding and the immune system: unintended consequences
​    3/1/2017  The questions PUPscan won't answer. Part 2: The answers
  2/28/2017  The questions PUPscan won't answer. Part 1
    2/5/2017  Latest OFA statistics for hip dysplasia (Dec 2016)
​    2/2/2017  Why didn't Antarctic sled dogs have hip dysplasia?
  1/23/2017  Your handy DNA testing crib sheet
​  1/18/2017  Rescuing the Norwegian Lundehund: an update from Milo
    1/3/2017  Comparing levels of inbreeding in dogs and horses
12/26/2016  Inbreeding of purebred dogs determined from DNA
​12/15/2016  NEW: ICB Genetic Diversity Certification
  12/9/2016  Why we need a more wholistic approach to managing canine genetic disorders
  12/7/2016  A simple new tool for genetic disease management
​  12/4/2016  The ICB Breeder Tool: Overview 
11/26/2016  Dog breeding in the era of genomic selection
11/23/2016  The new ICB Genomic Breeding Tool: the Genomic Relationship Coefficient
  9/18/2016  How to develop effective strategies for the genetic management of your breed
    9/2/2016  Preventing transmission of infectious disease at dog shows and sporting events
  8/31/2016  Gone too soon? Enough already.
  8/27/2016  Hip dysplaysia facts, fallacies, and fairy tales
​  8/16/2016  Why you should care about effective population size
  8/14/2016  The world's oldest cancer...in dogs 
    8/7/2016  Introducing a new course: The Biology of Dogs
  7/29/2016  Bulldog breeders: a call to action
​  7/23/2016  Try these breeding games!
    7/4/2016  Genes and the amazing mind of the dog
    7/2/2016  A game-changer for breeders: the ICB Breeder Tool
  6/30/2016  Understanding the heritability of behavior in dogs
  6/24/2016  Certificate of Completion: Genetics of Behavior & Performance course
    6/5/2016  Are we watching the extinction of a breed? (part 2)
    6/4/2016  Are we watching the extinction of a breed?
  4/15/2016  A broader view of extinction risk of dog breeds in the UK
    4/2/2016  A call for preservation breeding
​  3/29/2016  Twenty key elements of a successful breeding program
  3/28/2016  Breeds with the BEST & WORST genetic diversity 
  3/25/2016  What are we going to do about Terriers?
  3/20/2016  Evaluating the genetic status of a breed using both pedigrees and DNA
  3/15/2016  Reprise: The Pox of Popular Sires
​  3/13/2016  That purebred vs mixed breed thing again
    2/7/2016  Do you know what you don't know?
​  1/31/2016  Do you REALLY need to take a genetics course?
  1/27/2016  Three key strategies to reduce genetic disorders in dogs
  1/17/2016  Is it Nurture or Nature?
    1/2/2016  Managing risk factors for hip dysplasia
​12/23/2015  How do hips become dysplastic?
​12/21/2015  Reliability of DNA tests for inherited diseases in dogs
12/16/2015  Virtual tours of the canine hip and pelvis
12/11/2015  The 10 most important things to know about canine hip dysplasia
  11/4/2015  Coming soon: Course Certifications!
  11/2/2015  Brachycephaly: it's more than just the pretty face
10/24/2015  The poop about dog diets
​10/12/2015  Is (raw) diet the problem?
10/10/2015  Do dogs have more cancer than other mammals? 
  9/29/2015  Myths and mysteries about hip dysplasia  
  9/21/2015  Genetic status of purebred dogs in the UK
  9/16/2015  Bigger puppies develop hip dysplasia
  9/14/2015  The Mongolian Bankhar Dog Project
    9/5/2015  Citizen Scientists: Let's do something about hip dysplasia!
    9/1/2015  Major 2015 epilepsy consensus report
  8/26/2015  Genetics, behavior, and puppy temperament testing
  8/24/2015  The problem with the immune system: if you break it, it's yours  
  8/22/2015  Managing genetic disorders: "Just eliminate the bad gene"
    8/9/2015  Is the dam more important than the sire?
    7/8/2015  Decoding the genetics of behavior in dogs
  6/23/2015  Looking for early pedigree data?
  6/14/2015  For genetic improvement, it's the mix that matters
  6/12/2015  The relationship between inbreeding and genetic disease
    6/9/2015  Putting dogs to work for conservation
    6/4/2015  COI FAQs: Understanding the Coefficient of Inbreeding
    6/2/2015  Solving the problem of genetic disorders in dogs
  5/14/2015  Visualizing inbreeding on the chromosome  
  4/30/2015  The trouble with Terriers
  4/29/2015  Vulnerable breeds: how small is too small?
    4/1/2015  A bright future for purebred dogs
  3/29/2015  Health of purebred vs mixed breed dogs: the actual data
  3/27/2015  Finding genes without DNA
  3/26/2015  Tracing the paths of drifting genes
  3/24/2015  If knowledge is power, know every puppy
  3/19/2015  Lush on linebreeding
  3/12/2015  Why all the fuss about inbreeding? (Or "Why are there so many genetic disorders in dogs?")    
    3/7/2015  What does "health tested" really mean?
    1/9/2015  The history of purebred dogs in the UK
    1/5/2015  Genetic test for renal dysplasia (Caution advised)
    1/2/2015  A better way to pick 'em: using EBVs to reduce genetic disorders in dogs
    1/1/2015  Estimating the breeding value of a dog
12/31/2014  Why do dogs get cancer?
12/28/2014  Cryptorchidism is complicated
12/26/2014  Silent secrets in old dog bones
12/22/2014  The myth of hybrid vigor in dogs...is a myth
12/17/2014  Hitting the bottle: the genetics of boom and bust
  12/4/2014  More on tending the genetic pantry
  12/1/2014  Using inbreeding to manage inbreeding
11/25/2014  Why dogs are sloppy drinkers (and cats aren't)
11/21/2014  The complexity of coat color
11/18/2014  Epilepsy incidence and mortality in 35 dog breeds
  11/9/2014  Reducing genetic risk
  11/7/2014  Take the breeder quiz!
  11/6/2014  Dealing with those pesky mutations
10/31/2014  It's not always as simple as dominant and recessive
  11/9/2014  The fiction of "knowing your lines"
10/24/2014  Is your breed drifting?
10/23/2014  Who's tending your genetic pantry?
10/15/2014  How breeding the best to the best can be worse
10/10/2014  When Should You Spay or Neuter Your Puppy?
  10/3/2014  Genetic disorders in dogs: breaking the machinery of life
  9/25/2014  Get Started Using Estimated Breeding Values (EBVs)
  9/19/2014  The Costs and Benefits of Inbreeding
  8/27/2014  A bit of sheepish fun
  8/20/2014  How many generations of pedigree data should you use to estimate inbreeding?
  7/23/2014  Me, jealous?  Never!  But my dog, on the other hand...
  7/20/2014  Population Size & Inbreeding
  7/19/2014  Avoiding inherited genetic diseases in dogs
  6/18/2014  Wright’s Coefficient of Inbreeding
    6/5/2014  Why DNA tests won't make dogs healthier
    6/1/2014  Eliminating genetic disorders in dogs - too little, too late?
    5/2/2014  Better hips and elbows?  Maybe.
    5/1/2014  Cancer Surprises
  2/21/2014  Genetic Management of Dog Breed Populations
    2/2/2014  What Does Population Genetics Have To Do With Breeding Dogs?
  12/5/2013  The Pox of Popular Sires
  10/5/2013  A bit more about Poodles
  9/24/2013  An open letter to the Canadian Poodle clubs and others that love the breed
  7/23/2013  Why do dogs have so many genetic disorders?
  7/19/2013  Primary lens luxation is WIDESPREAD among dog breeds - are you testing?
  7/18/2013  Inherited myopathy in Labradors is found worldwide - the legacy of a popular sire
    7/2/2013  Finally, a scientific journal about Dogs!
    3/9/2013  How molecular genetics will change dog breeding
    7/6/2012  Locating the genes for hip dysplasia in dogs (Psssst! Look in the kibble bag)
  4/19/2012  Population genetics suggests dire straits for Tollers and Heelers

If the head of the femur conforms to the shape of the socket with no looseness, the hip will develop normally and hip dysplasia will not occur. But any looseness in the hip joint triggers the vicious cycle of bone deformation and remodeling that results in hip dysplasia. Laxity in the hip joint is the basis of the "distraction index" (DI), one of the statistics used by PennHip to evaluate hip phenotype (xxxx).

​The key to preventing hip dysplasia, then, is to prevent the development of laxity in the joint.

This ligament is very short and tight at birth, restricting the range of motion of the femur by keeping the head of the femur well-seated in the cup of the hip socket. This is why a newborn puppy on its back will hold the legs a bit to the sides with the stifles bent. As the puppy grows, this ligament gradually lengthens and the range of motion of the legs increases until the femur can be extended parallel to the axis of the body. (The same ligament is present in humans, which is why a baby on its back also holds its legs at rest in the same flexed position.)

To solve the joint laxity problem, we need to understand what is causing the joint to be loose. This would probably still be a mystery if not for some observations about the occurrence of hip dysplasia in different populations of humans.

Hip dysplasia is more prevalent in some cultures than others. It is rare in African cultures (0.06 per 1000 live births; Loder & Skopelja 2011), while the recorded incidence in Navajo Indians is among the highest, ranging from 10.9 per 1,000 population (Rabin et al. 1965) to 76.1 per 1,000 (Blatt 2014). It would be tempting to attribute these population differences in the incidence of hip dysplasia to genetics. However, some animal studies  revealed that there could also be non-genetic (environmental) causes. In particular, animal studies showed that hip dysplasia could be induced simply by prolonged (days or weeks) extension of the back legs (Wang et al. 2012).

An association between hip dysplasia in infants and the way they were swaddled was highlighted by the results of an educational campaign to reduce dysplasia in Japan (Yamamuro & Ishida 1983). The incidence of hip dysplasia in infants in Japan prior to 1965 was high, estimated at 1.1%-3.5%. An educational campaign begun in 1975 encouraging parents to reduce prolonged extension of the legs while swaddled achieved a marked reduction in the incidence of hip dysplasia, to about 0.2%.

​

POTENTIAL CONSEQUENCES OF TERES LIGAMENT DAMAGE
Orthopedic
  Hip dysplasia
  Legg-Calves-Perthes
  Luxating patella
  Pes varus
  Cruciate ligament rupture
  Flat chest / Swimmers
  Elbow dysplasia?

Neurological
  Wobblers
  Spinal compression (e.g., pug myelopathy, degeneratiove myelopathy)
​  

​NEUROLOGICAL
Pug myelopathy
​

OTHER ANIMALS

Cats
Rabbits

Captive wildlife
 - Snow leopard
 - Panda

Domestic animals
 - pigs ("spraddle leg")
 - birds

REFERENCES

Loder RT & EN Skopelja. 2011. The epidemiology and demographics of hip dysplasia. ISRN Orthopedics, Vol 2011, Article ID 238607. ​doi:10.5402/2011/238607.

Mahan ST & JR Kasser. 2008. Does swaddling influence developmental dysplasia of the hip? Pediatrics 121:177-178. DOI: 10.1542/peds.2007-1618.

Rabin DL, CR Barnett, WD Arnold, RH Freiberger, & G Brooks. 1965. Untreated congenital hip disease: a study of the epidemiology, natural history, and social aspects of the disease in a Navajo population. Am. J. Public Health Nations Health 55 (Suppl 2): SUPPL: 1-44.
 
Blatt SH. 2015. To swaddle, or not to swaddle? Paleoepidemiology of developmental dysplasia of the hip and the swaddling dilemma among the indigenous populations of North America. Am. J. Human Biology 27: 116-128.

Wang e, T Liu, J Li, EW Edmonds, Q Zhao, L Zhang, X Zhao, & K Wang. 2012. Does swaddling influence developmental dysplasia of the hip? J. Bone & Joint Surgery 94:1071-1077.

Yamamuro T & K Ishida. 1984. Recent advances in the prevention, early diagnosis, and treatment of congenital dislocation of the hip in Japan. Clinical Orthopaedics and Related Research 184 4:40. 
​