Hip Dysplasia and Osteoarthritis

Hip Dysplasia in Dogs: A Guide for Dog Owners

Reference = Foster, J. (1996) Hip Dysplasia in Dogs: A Guide for Dog Owners. British Veterinary Association, London: You and Your Vet.

  • HD is a term encompassing a number of specific developmental and other abnormalities of the hip joint
  • Developmental changes related mainly to growth are known as primary changes. Wear and tear from usage are secondary changes. End results are mechanically unsound joints not functioning properly
  • Affected joints are usually painful and lameness will result. Extreme cases make movement difficult with a lot of suffering
  • A scheme has been developed to assess HD status through radiography primarily for breeders use with 97 breeds surveyed by the scheme
  • Argued that dogs aren’t born with HD. Hip development can worsen with time most notably during rapid growth phase (14-26 weeks of age)
  • Unwelcome changes start in early puppyhood with first usage, continuing into adulthood
  • Wear and tear from exercise is followed by inflammation and degeneration
  • BVA/KC HD scheme scores HD severity from zero (best) to 53 (worst) giving the range for the total of 0-106 with a breed mean score and breed range
  • Not surprising of high rates of HD considering some animals treble in size in a 3 month period of adolescence
  • Getting the right nutritional needs in the right quantity is difficult but important and overlays inheritance and other factors (e.g. Exercise and degree of body weight)
  • Because of the many underlying factors involved (joint looseness, bone formation or loss, inflammation and pain) and varying presented signs (from apparent soundness through to lameness and exercise intolerance) there is no predicting the degree of HD just by looking from the outside
  • Clinical examination more reliable revealing movement limitation, proabable reduction in muscle mass of affected limb and some degree of pain (dogs won’t show clear signs as discomfort will be relatively constant as opposed to sudden pains). Radiography the only real diagnosis tool
  • 2 main factors of likeliness of HD and severity – inheritance (genetic code) and environmental factors (outside influences altering growth and structural functions)
  • Applied heat, massage, good bedding and correct exercise important when caring for dog with HD
  • For dog to get hip x-ray, appointment should be made with vet for hip radiography under the scheme (minimum age = 12 months)

Treatment of Hip Dysplasia

Reference = Anderson, A. (2011) Treatment of Hip Dysplasia. Journal of Small Animal Practice, 52: 182-189.

  • Common development disorder of hip joint characterised by laxity and subsequent development of osteoarthritis
  • Progression of HD dependent on genetic susceptibility and environmental factors
  • Can occur in all dogs but more so in medium and larger sized breeds
  • Discomfort in young dogs (4-8 months) usually due to hip laxity. Although clinical improvement associated with improved hip stability can be seen in the following months due to development of joint capsule thickening, periarticular fibrosis and healing of microfractures of dorsal acetabular rim
  • Hip laxity and development of osteoarthritis have a relationship, although the likeliness of developing osteoarthritis based on laxity varies between breeds (Smith et al., 2001)
  • Discomfort in older dogs usually due to osteoarthritis development
  • German Shepherds have 5 times the risk of osteoarthritis compared with combined risk of Labradors, Golden Retrievers and Rottweilers (Smith et al., 2001) based on radiography DI, all having the same DI
  • Aim of treatment is to reduce or eliminate pain to restore or improve limb function
  • Firstly conservative management and then surgical procedure
  • Decision making influenced by many factors (age, severity of signs and radiographic changes, behaviour and potential use)
  • Conservative management aims to reduce or eliminate pain through exercise restriction, weight control, analgesics (normally non-steroidal anti-inflammatory drugs) and physical therapies
  • Barr et al. (1987) followed up 50 dogs with moderate to severe radiographic signs of HD (mean age at presentation of 8 months) for a mean period of 4.5 years undergoing some form of conservative management with 76% displaying no signs or very little change in rear limb gait by owners. 19 of the 50 were then assessed by a vet who reported 89% having no gait abnormality or slight pelvic sway – Positive report of conservative management
  • Although another study (Farrell et al., 2007) showed conflicting results where 42-66% of tested dogs were clinically affected at a follow up (median age at presentation:follow up = 1 year:5 years) with 40% requiring NSAIDs. With a reassessment of a smaller portion of the dogs by a vet showing lameness in 92% with high muscle atrophy, restricted motion and pain on extension
  • A study comparing treatments showed more lameness, less gluteal muscling and more pain and restrictions on extension with conservative management over other options although signs generally mild and only 20 dogs assessed (Plante et al., 1997)
  • Examples of no difference in total number of months worked/time of retirement between dogs with mild or moderate HD and dogs with no HD in military (Barnfield et al., 1996) and guide dogs (Pfaffenberg et al., 1976)
  • Diet (quantity of food thus affecting weight) has been shown to have a significant effect on dogs predisposed to HD. Labradors fed 25% less food (8 months to 2 years) had less joint laxity (Kealey et al., 1992) and had significantly lower prevalence of osteoarthritis when followed up later in life (Kealy et al., 2000)
  • Overweight dogs with osteoarthritis fed calorie-restricted diets resulting in weight loss improved significantly at least in the short term (Mlacnik et al., 2006) as excess body weight increases stress on joints and can contribute to degradation of articulate cartilage
  • Surgery options available to help prevent or limit development of HD and osteoarthritis
  • Wide range of treatment options potentially available

Lifelong Diet Restriction and Radiographic Evidence of Osteoarthritis of the Hip Joint in Dogs

Reference = Smith, G.K. et al. (2006) Lifelong Diet Restriction and Radiographic Evidence of Osteoarthritis of the Hip Joint in Dogs. Journal of the American Veterinarian Medical Association, 229(5): 690-693. 

  • This study tested 48 Labradors split into 2 groups of 24 (paired off from same litter based on similar size and characteristics), one fed a control diet and the other fed 25% less for life with hip joints radiographed every year at the same time, in an attempt to see if reduced weight plays a role in reduced prevalence and delayed onset of osteoarthritis
  • Overall prevalence of osteoarthritis did increase from 15% at 2 years to 67% at 14 years although restricted-fed dogs had lower prevalence and later onset. Median age at first onset of osteoarthritis was 6 years in control fed and 12 years in restricted-fed
  • Restricted feeding delayed or prevented osteoarthritis in these Labradors favourably affecting duration and quality of life
  • HD is highly prevalent, progressive and frequently debilitating and its expression can be influenced a great deal by environmental factors
  • HD can be as high as 73% in some breeds (Paster et al., 2005)
  • Generally accepted that degenerative changes occur in all dogs as they age, with HD showing signs of osteoarthritis very prematurely in comparison (Morgan et al., 2000)
  • Initial expression of HD of femoral head subluxation (unnatural fit in the socket; slight dislocation) in the hip
  • Incorrect positioning can result in abnormal loading leading to cartilage damage and bone remodelling. This results in osteoarthritis characterised by synovitis, increased joint fluid, cartilage erosion, elongation and edema (swelling from fluid) of the round ligament, thickening of joint capsule and osteophyte (bony projection) formation
  • Conventionally believed that no increase in hip osteoarthritis and joint laxity after age 2 so suggested studies only needed to be taken between 1 and 2 years of age (Jessen & Spurrell, 1972). This current study refutes that as there is a constant rate of development in change of radiographic evidence of hip osteoarthritis throughout life
  •  Many studies have highlighted the role of obesity in joint degeneration and the importance of calorie controlled diets in many animals and species to help prevent of reduce associated issues such as osteoarthritis (Bendele & Hulman, 1991; Felslon, 1996). Although dogs vary considerably between one another so one energy intake cannot be specified for all, so lean body conformation (body condition score of 4 or 5) is recommended through appropriate caloric restriction after 8 weeks (Kealy et al., 2002; Bodkin et al., 2003)
  • Important to consider same results may not be replicated in shorter term feeding restrictions and in breeds less susceptible to HD, although that isn’t to say that results wouldn’t be the same, just more evidence needed. Important to keep susceptible dogs lean throughout life

Diagnosis, Genetic and Preventitive Management of Canine Hip Dysplasia: A Review

Reference = Ginja, M.M.D., et al. (2010) Diagnosis, Genetic Control and Preventive Management of Canine Hip Dysplasia: A Review. The Veterinary Journal, 184: 269-276.

  • HD seen as one of the most common orthopaedic diseases in dogs
  • Vast majority of affected dogs show minimal to no clinical signs, but can be highly debilitating
  • Hip joint laxity is a major risk of developing degenerative joint disease
  • HD is an inherited, non-congenital disease particularly prevalent in larger breeds of dog (Ginja et al., 2008) with environmental factors influencing expression (Silvestre et al., 2007)
  • HD is a biomechanical disease characterised by abnormal hip joint development that can be very debilitating (Vezzoni et al., 2008)
  • Medical and/or surgical intervention is needed for badly affected dogs (Farrel et al., 2007)
  • Hip joint laxity causes abnormal weight bearing that may lead to osteoarthritis during or after maturity (Smith et al., 1995)
  • Some of the chronic alterations (bony remodelling, fibrosis, thickening of the joint capsule) can on occasion improve limb function by improving joint congruity and stability (Barr et al., 1987)
  • 2 ages where clinical signs are shown: Younger than 1 year of age with instability and overloading of articulate areas causing tearing and stretching of round ligament, synovitis and acetabular microfractures (Manley et al., 2007); and in adult dogs with chronic pain from osteoarthritis
  • Typical signs include – gait abnormalities in the forms of: stiffness, reduced height of step shortened stride length, bunny hopping, difficulty in rising, climbing stairs and jumping obstacles (Ginja et al., 2008)
  • Barlows test, Ortalani test and Barden’s test used to help hip joint laxity by manipulating the femoral head and following protocols to check for indicators that can then be used to suggest presence of HD. Although other researchers have failed to repeat Barden’s findings, and due to subjectivity involved it makes predictions of HJL and HD unreliable (Ginja, et al., 2009)
  • Has been determined that HD with only subtle radiographic signs can still influence joint kinematics (Bockstahler et al., 2007)
  • HD is largely affected by genetic inhertance with expression modified by environmental risk factors such as nutrition, exercise, body weight, birth weight, number of puppies in litter, age of the dam, floor cover, pre-weaning mortality rate in litter, season of birth and hip laxity (Maki et al., 2000; Ginja et al., 2008)
  • Hip joint laxity heritability shown to be higher than HD heritability (Ginja et al., 2008)
  • Difficult to prevent HD by stopping symptomatic dogs from breeding as many a symptomatic dogs are still carriers and pass the involved genes on to their offspring
  • Treatments are focuses on pain reduction and improved function of hip joints and quality of life (Farrell et al., 2007)
  • Dogs can show signs of pain at 5-6 months with apparent dismissal of pain at 9-11 months likely due to healing of microfractures and dorsal acetabular rim (Riser, 1975). Restricting exercise at this time can help prevent worsening of secondary arthritic changes that occur wit HD (Vezzoni et al., 2008)
  • Prevention of obesity recommended to reduce stress placed on joints
  • Swimming is a great exercise alternative to reduce undesirable secondary effects