Genetic diseases with multiple modes of inheritance

Hip Dysplasia

Current thoughts on hip dysplasia

Scientists now realize that hip dysplasia is caused by multiple genes and that the severity and progression of the disease are dependent upon a dog’s genetic susceptibility and exposure to certain environmental factors(Runge 2010).

Hip dysplasia has been studied for over 50 years, and breeders have been trying to eliminate it in their programs for years, yet it still exists, and the prevalence has actually increased in later years (Junutta 2008). Some research shows that genetics only account for 15-40% of the variation in hip scores, so influence from environmental factors is huge (Lewis 2013).

What is hip dysplsia?

Hip dysplasia is a condition where the hip joints are loose. This laxity allows the head of the femur bone to not align properly in the hip socket. Over time, this misalignment leads to abnormal wear on cartilage surfaces resulting in inflammation, pain and osteoarthritis.

Current testing and test problems

There is no genetic test available.

There are 2 organizations that will rate hips on dogs: OFA and Pennhip. Dogs are sedated and X-rays are taken. This needs to be performed by veterinarians who have undergone training on how to properly align hips during the procedure. These x-rays are then sent off to OFA or Pennhip, where they are graded by radiologists.

There are several problems with this method. One is that if the dog’s legs are not properly aligned during the X-ray, the X-ray may not be accurate. The other is that there may be human error in actually scoring the X-rays.

The OFA classifies hips into 7 categories:
• Excellent, Good, and Fair – these are all within normal limit
• Borderline – results are not clear
• Mild, Moderate, and Severe – these all indicate some form of dysplasia

Scores reflect the hip laxity in individuals and do not necessarily reflect the genetics. Remember that there are multiple genes involved and that those genes have not been identified at this time.

There have been multiple cases where 2 dogs with excellent hip ratings have produced puppies with poor hips. This may be due to the fact that the environment plays a HUGE role in the development of hip dysplasia.

We still perform OFA tests on our dogs even though we are aware that research shows that using these values has not led to a reduction in hip dysplasia, nor is it a great indicator in determining if a puppy will or will not develop hip dysplasia in the future.

Hedhammar A, F-M Wu, L Krook, HF Schryver, A de Lahunta, FP Whalen, FA Kallfelz, EA Nunez, HF Hintz, BE Sheffy, & GD Ryan. 1975. Overnutrition and skeletal disease: An Experimental Study in Growing Great Dane Dogs. Cornell Vet 64: Supp 5

Janutta V, Hamann H, Distl O. Berl Munch Tierarztl Wochenschr. 2008. Genetic and phenotypic trends in canine hip dysplasia in the German population of German shepherd dogs. 21:102-109.

Kealy RD, DF Lawler, JM Ballam, SL Mantz, DN Biery, EH Greeley, G Lust, M Segre, GK Smith, & HD Stowe. 2002. Effects of diet restriction on life span and age-related changes in dogs. J. Am. Vet. Med. Assoc. 220: 1315-1320.

Krontveit RI, A Nodtvedt, BK Saevik, E Ropstad, & C Trangerud. 2012. Housing- and exercise-related risk factors associated with the development of hip dysplasia as determined by radiographic evaluation in a prospective cohort of Newfoundlands, Labrador Retrievers, Leonbergers, and Irish Wolfhounds in Norway. Am J Vet Res 73: 838-846.

Lewis, TW, SC Blott, & JA Woolliams. 2013. Comparative analyses of genetic trends and prospects for selection against hip and elbow dysplasia in 15 UK dog breeds. BMC Genetics 14:16.

Runge JJ, Kelly SP, Gregor TP, et al. 2010, Distraction index as a risk factor for osteoarthritis associated with hip dysplasia in four large dog breeds. J Small Anim Pract 51:264-269, 2010.

How does the enviroment play a role?

Environmental factors play a HUGE role in determining if a dog will develop hip dysplasia.

Research shows that all puppies are born with normal hips therefore hip dysplasia in not a congenital defect (Riser 1985) but environmental factors starting in puppyhood may influence their chance of developing hip dysplasia later in life.

What can be done to prevent hip dysplasia?

Both the breeder and the new owner can both play a part in preventing hip dysplasia. The list below are things that we monitor and suggest to new owners.

• Providing excellent footing in the whelping crate

We make sure that babies are raised on a surface with excellent traction to prevent slipping (Krontveit 2012).

• Not breeding dogs who have hip issues.

The current thought is that hip dysplasia is caused by multiple genes and environmental factors; therefore, dogs with bad hips should not be bred.

• Monitor weight in pregnant females

We closely monitor weight in our females to prevent large puppies that will have a hard time moving around (Riser 1985).

• Monitor weight in ALL dogs

We weigh our dogs and evaluate their body condition on a monthly basis. We then adjust the amount of food that they receive to keep their weight in check. Excessive weight applies extra pressure to joints.

• Diet

Research shows that dogs kept on a restricted diet are 25% less apt to develop hip dysplasia than dogs that are overweight and they live longer too (Kealy 2002). Obesity may be the single most significant environmental factor.

• No stairs for the first 3 months

We do not expose our puppies to stairs before they leave and recommend that new owners prevent their puppies from going up or down stairs until the puppies are 3 months old. (Krontveit 2012)

• Hand feeding puppies

Research shows that puppies kept on a restricted diet have a much lower rate of hip dysplasia.(Hedhammar 1975) We do not free feed our puppies. We also move our puppies to a high quality adult formula between 6 and 8 months of age.

• Feeding a high-quality food

We feed all of our adults and puppies a high-quality food. Research shows that dogs fed high quality foods have a lower incidence of hip dysplasia than those fed lower-quality food. High-quality foods take into account Calcium – Phosphorus ratios, protein levels, and undergo feeding trials.

• Age-appropriate exercise

Our puppies and adults all receive daily exercise based upon their age and stage of development. Research shows that dogs who receive appropriate daily exercise have a lower incidence of hip dysplasia. The key is low-strenuous exercise and not overexertion. Please note that too much exercise, prolonged periods of exercise, high-impact exercise, or allowing puppies to tussle and play hard with other dogs or puppies can actually increase the rate of hip dysplasia.

We send home exercise guidelines with every puppy outlining age-appropriate exercise based upon age.