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Canine hip dysplasia (CHD) is a polygenic and multifactorial developmental disorder characterized by coxofemoral (hip) joint laxity, degeneration, and osteoarthritis (OA). Current diagnostic techniques are largely subjective measures of joint conformation performed at different stages of development. Recently, measures on three-dimensional images generated from computed tomography scans predicted the development of OA associated with CHD. Continued refinement of similar imaging methods may improve diagnostic imaging techniques to identify dogs predisposed to degenerative hip joint changes. By current consensus, joint changes consistent with CHD are influenced by genetic predisposition as well as environmental and biomechanical factors; however, despite decades of work, the relative contributions of each to the development and extent of CHD signs remain elusive. Similarly, despite considerable effort to decipher the genetic underpinnings of CHD for selective breeding programs, relevant genetic loci remain equivocal. As such, prevention of CHD within domestic canine populations is marginally successful. Conservative management is often employed to manage signs of CHD, with lifelong maintenance of body mass as one of the most promising methods. Surgical intervention is often employed to prevent joint changes or restore joint function, but there are no gold standards for either goal. To date, all CHD phenotypes are considered as a single entity in spite of recognized differences in expression and response to environmental conditions and treatment. Identification of distinct CHD phenotypes and targeting evidence-based conservative and invasive treatments for each may significantly advance prevention and management of a prevalent, debilitating condition in canine companions.
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Veterinary Medicine: Research and Reports 2015:6 181–192
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REVIEW
open access to scientific and medical research
Open Access Full Text Article
http://dx.doi.org/10.2147/VMRR.S53266
Diagnosis, prevention, and management
of canine hip dysplasia: a review
Emma R Schachner
Mandi J Lopez
Department of Veterinary Clinical
Sciences, School of Veterinary
Medicine, Louisiana State
University, Baton Rouge, LA, USA
Correspondence: Mandi J Lopez
Department of Veterinary Clinical
Sciences, School of Veterinary Medicine,
Louisiana State University, Skip Bertman
Drive, Baton Rouge, LA 70803, USA
Tel +1 225 578 9918
Email mlopez@lsu.edu
Abstract: Canine hip dysplasia (CHD) is a polygenic and multifactorial developmental disorder
characterized by coxofemoral (hip) joint laxity, degeneration, and osteoarthritis (OA). Current
diagnostic techniques are largely subjective measures of joint conformation performed at dif-
ferent stages of development. Recently, measures on three-dimensional images generated from
computed tomography scans predicted the development of OA associated with CHD. Continued
refinement of similar imaging methods may improve diagnostic imaging techniques to iden-
tify dogs predisposed to degenerative hip joint changes. By current consensus, joint changes
consistent with CHD are influenced by genetic predisposition as well as environmental and
biomechanical factors; however, despite decades of work, the relative contributions of each
to the development and extent of CHD signs remain elusive. Similarly, despite considerable
effort to decipher the genetic underpinnings of CHD for selective breeding programs, relevant
genetic loci remain equivocal. As such, prevention of CHD within domestic canine popula-
tions is marginally successful. Conservative management is often employed to manage signs of
CHD, with lifelong maintenance of body mass as one of the most promising methods. Surgical
intervention is often employed to prevent joint changes or restore joint function, but there are
no gold standards for either goal. To date, all CHD phenotypes are considered as a single entity
in spite of recognized differences in expression and response to environmental conditions and
treatment. Identification of distinct CHD phenotypes and targeting evidence-based conservative
and invasive treatments for each may significantly advance prevention and management of a
prevalent, debilitating condition in canine companions.
Keywords: canine hip dysplasia, orthopedics, joint, osteoarthritis
Introduction
Canine hip dysplasia (CHD) is a complex developmental disorder characterized by joint
laxity and osteoarthritis (OA) in one or both coxofemoral (hip) joints (Figure 1A–C).1
The polygenic, multifactorial etiology2 of CHD has challenged veterinarians and
researchers since the condition was described in the 1930s.3 Joint changes characteristic
of CHD are also associated with environmental factors such as nutrition,4–6 exercise,7
and the process of skeletal ossification.8,9 The condition affects essentially all breeds,
with an estimated prevalence ranging from 1% to 80% according to the Orthopedic
Foundation for Animals. It appears to occur at a relatively high rate in large-bodied
and brachycephalic dogs as well as those with high body length to height ratios.10,11
The periodic appearance of OA in joints other than the coxofemoral joint12,13 has led
some to propose systemic contributions to CHD expression.1 These complexities,
among others, complicate attempts to manage the CHD by selective breeding despite
strict reporting and guidelines.14
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Schachner and Lopez
There are many theories to explain CHD joint degenera-
tion, but joint laxity and irregular or delayed endochondral
ossification are among the most popular. The conditions are
not mutually exclusive, and their phenotypic expression is
variable within and among breeds.15 Partially ossified hip
structures may become distorted during development due
to mechanical stresses in joints with delayed endochondral
ossification.8,16 Joint components may be more vulnerable to
deformation and damage from normal joint kinetics before
they are fully ossified.8,9,17 Abnormal and delayed endochon-
dral ossification in the coxofemoral joint has been identified
in 15-day-old dogs that developed CHD by the time they were
12 months old,8,9,18 and in Great Danes with experimentally
induced hip dysplasia.19 In contrast, comparably earlier joint
ossification appears to occur in Greyhounds, a breed with
one of the lowest incidences of CHD. While it is clear that
variation in the process of endochondral ossification may play
a role in the development of CHD, the exact relationships
between ossification patterns, abnormal joint structure, and
development of OA remain unclear.20
Affected joints usually develop varying degrees
of synovial inflammation, articular cartilage damage
( Figure 1), osteophytes, and subchondral bone sclerosis and
remodeling.21–23 While there is no single, overarching descrip-
tion of the sequence of events in the process, there are changes
that occur in many forms of dysplasia. Recently, the dorsal
acetabular rim angle (a measure of the dorsal slope [angle] of
the subchondral articular acetabular surface relative to hori-
zontal) was reported to be significantly larger (less femoral
head coverage by the acetabulum) in dogs with coxofemoral
joint laxity versus normal dogs as early as 1 week of age.17
Subluxation of the femoral head and delays in ossification
Figure 1 Anatomy of canine hip dysplasia.
Notes: (AC) Canine hip-extended radiographs, and corresponding images of the joints (DF) from different individuals demonstrating mild (A and D), moderate (B and E),
and severe (C and F) joint changes. Light photomicrographs of normal (G) and brillated (H, arrow) articular cartilage.
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Canine hip dysplasia
of the craniodorsal acetabular margin are often visible by
8 weeks, and, in many cases, subluxation of the femoral
head increases by around 12 weeks of age.18 Degeneration
and microfractures of the articular cartilage, and thickening,
inflammation, and deterioration of the joint capsule, tendi-
nous insertions, and ligaments are often apparent by 5 months
of age.18 Despite the presence of these degenerative traits in
many dogs with degenerative coxofemoral joint changes,
clinical signs are variable.21
A direct relationship between joint capsular collagen
composition and mechanical properties was proposed over
30 years ago.24 Altered capsular collagen composition has
been identified in children with congenitally dislocated
hips25 and dogs with hip joint laxity.26 Joint capsular collagen
fibrils were found to be more heterogeneous in 8-month-old
Labrador Retriever puppies with severe coxofemoral joint
laxity than those with normal joints.15 Abnormal collagen
composition is thought to contribute to reduced joint capsule
stiffness, which contributes to excess femoral head motion
and abnormal mechanical stresses on the femoral greater
trochanter and acetabular margins and cartilage.15 Over time,
the abnormal forces are thought to result in deformation of
the articulating structures and an incongruous joint.18
Despite almost a century of work, many aspects of the
development and progression of joint changes and OA associ-
ated with CHD remain elusive. This makes establishment of a
gold standard for treatment a challenge. The lack of a single,
predictable pattern of joint degeneration is likely a reflection
of natural variability, including individual responses to exter-
nal environmental influences. However, ambiguity in disease
progression may also reflect distinct disease processes that
have yet to be recognized. Continued efforts to identify and
characterize patterns in joint changes may lead to identification
of CHD phenotypes, which will, in turn, contribute to earlier
disease identification and more effective targeted treatments.
Diagnosis
Despite some recognized patterns of joint degeneration
characteristic of CHD, there is significant variability in the
progression and ultimate severity of the disease as well as
inconsistent relationships between gross and radiographic
joint changes and clinical signs.21 There are, however, two
general behaviors often attributed to CHD, including lame-
ness in young dogs (under 1 year), that increases with activity
or trauma, and gait abnormalities and hind limb muscle atro-
phy in older dogs.27 Notably, hind limb lameness can be due
to reasons other than CHD joint changes, including pelvic,
distal hind limb, and neurological pathologies, metabolic
bone disease, ligament rupture, patellar luxation, and spine
disorders.27 Hence, a thorough, comprehensive assessment is
paramount to identification of the source of discomfort.
Subjective laxity examinations
The Ortolani test is a subjective evaluation of coxofemoral joint
laxity originally designed for diagnosis of human congenital
hip dislocation in the 1930s.28,29 The test is also used as a CHD
screening test.28 Dogs are placed in lateral recumbency; one
hand of the examiner is used to apply force along the length of
the femur from the stifle toward the pelvis as the other braces
the back just above the sacrum (Figure 2).27 This maneuver is
intended to displace the femoral head. The stifle is then slowly
abducted to reduce the joint.29 An audible or palpable pop as the
femur slips back into the acetabulum is considered a positive
Ortolani sign indicative of joint laxity. Lack of an Ortolani
sign does not necessarily mean that the hip is normal. Joint
changes associated with dysplasia, like thickening of the joint
capsule and joint tissue, may interfere with the displacement
required for a positive sign.28,30 Bardens’ test,31 an examination
technique designed to evaluate the hips of babies (aged younger
than 6 months), is thought to be more sensitive for detecting
coxofemoral joint laxity and/or shallow acetabula in puppies
6–8 weeks of age.29 With the dog in lateral recumbency, the
proximal femur is elevated laterally from the body. With the
femur elevated, the index finger of the other hand is used to
push the femur away from the joint in a dorsal direction with
pressure on the greater trochanter. More than 2 mm of displace-
ment is considered a positive sign.31 In general, these and other
palpation techniques may be used as part of a comprehensive
examination on puppies or dogs suspected to have excessive
joint laxity characteristic of CHD. However, the tests alone are
not sufficient for diagnosis of CHD.
Radiography
Radiography has long been the gold standard to assess
and quantify joint changes associated with CHD joint
remodeling.32,33 Worldwide, there are five popular, standard-
ized evaluation systems with distinct metrics that are used to
grade canine radiographic coxofemoral joint conformation
and degenerative changes.
Orthopedic Foundation for Animals
The Orthopedic Foundation for Animals evaluation is
performed on hip-extended radiographs performed under
heavy sedation or general anesthesia by three independent
board-certified radiologists.10 Based on subjective assess-
ment of nine joint parameters (Figure 3A), conformation
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Schachner and Lopez
is categorized as excellent, good, fair, borderline, mild,
moderate, or severe. The first three categories are considered
to be normal while the last three are dysplastic.10 Metrics
are largely subjective assessments of hip conformation and
evidence of degenerative joint disease.
British Veterinary Association/Kennel Club
The British Veterinary Association/Kennel Club maintains a
“pass/fail” evaluation system that was instituted in 1965 and
updated in 1984.34 For scoring, dogs must be at least 1 year
of age, microchipped (or tattooed), and, if registered with the
Kennel Club, the registration number must be included on the
radiograph.35 Each dog has one opportunity to be scored by the
system. Joints are individually scored on nine criteria from 0 to
5 or from 0 to 6 on hip-extended radiographs by two qualified
radiologists on a British Veterinary Association/ Kennel Club
panel, with 0 being the best score and 106 the worst (53 possible
points for each hip).34 The nine criteria ( Figure 3B) include the
Norberg angle (Figure 3C) and subjective assessments includ-
ing subluxation, dorsal acetabular edge, cranial acetabular
edge, cranial effective acetabular rim, acetabular fossa, femoral
head recontouring, and femoral head and neck exostosis.34,35
An average score for each individual dog breed is published,
ie, the breed mean score, and it is recommended that only
animals with total scores well below the breed mean be used
for breeding purposes.35
Fédération Cynologique Internationale
The Fédération Cynologique Internationale (FCI)36 is one
of the largest canine organizations in the world and includes
kennel clubs from across Europe, Asia, Africa, and South
America. Extended hip and abducted hind limb radiographs
performed at 1 year of age (18 months for large breed dogs)
are scored according to the official FCI system by radiologists
approved by breed-specific kennel clubs.36 Scoring includes
the Norberg angle, formed by a horizontal line connecting
the centers of the right and left femoral heads and a line con-
necting each center to the cranial margin of the corresponding
acetabulum (Figure 3C)37 as well as subjective hip conforma-
tion parameters. Each joint is assigned a grade of A–E, with
A representing healthy and E representing severe dysplasia.
The more dysplastic of the two joint scores is considered the
A
Acetabulum
Ligamentum
teres
Cartilaginous labrum
B
DC
Femoral head
Joint capsule
Figure 2 Schematic illustration of the Ortolani test.
Notes: Image demonstrates the coxofemoral joint prior to distraction (A), while force is applied from the stie toward the hip along the axis of the femur to displace the
femoral head (B), during abduction of the femur to reduce the joint (C), and with the femoral head snapping back into place with an audible click, ie, the Ortolani sign (D).
Arrows indicate the direction of the applied force. Adapted from Chalman JA, Butler HC. Coxofemoral joint laxity and the Ortolani sign. Journal of American Animal Hospital
Association. 1985;21:671–676.28
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Canine hip dysplasia
final score for the individual dog. The same grading scale can
also be applied to computed tomography (CT) scans.
Pennsylvania Hip Improvement Program
University of Pennsylvania researchers developed a quantita-
tive method to evaluate canine hip conformation38–40 that was
implemented in 1994.41 The primary distinction of the Penn-
sylvania Hip Improvement Program (PennHIP) method is that
passive hip joint laxity is measured in addition to subjective
radiographic conformation.38–40 Three radiographic views
are evaluated by PennHIP-certified radiologists: a standard
hip-extended view for evidence of degenerative joint disease;
a compression view for congruity between the femoral head
and acetabulum; and a distraction view, for joint laxity. The
distraction index is the ratio of the distance between the
centers of the femoral head and acetabulum (d) and the radius
of the femoral head (r), as shown in Figure 3D. The closer the
score is to 0, the better the fit, ie, minimal femoral distrac-
tion, but a score of 1 indicates severe laxity and associated
femoral distraction.41 Recently, the PennHIP distraction index
and OA scores were found to have strong correlations with
microstructural changes in the articular cartilage,42 potentially
indicating a relationship between joint laxity measured by
this technique and articular surface degeneration.
Dorsolateral subluxation
Dorsolateral subluxation is used to quantify joint laxity in
a position to simulate weight-bearing (Figure 3E). During
Figure 3 Representations of anatomical landmarks and evaluation mechanisms to assess canine hip dysplasia.
Notes: Coxofemoral joint anatomical characteristics considered by the Orthopedic Foundation for Animals (A): craniolateral acetabular rim (1), cranial acetabular margin
(2), femoral head (3), fovea capitis (4), acetabular notch (5), caudal acetabular margin (6), dorsal acetabular margin (7), junction of femoral head and neck (8), and trochanteric
fossa (9). (B) British Veterinary Association/Kennel Club canine coxofemoral joint characteristics scored during evaluation.10,34 Schematic superimposed on a hip-extended
radiograph demonstrating the Norberg angle (C, arrow). Illustration of the Pennsylvania Hip Improvement Program (distraction index, the distance between the centers of
the femoral head and acetabulum during distraction (D) divided by the radius (r) of the femoral head (d).41 Depiction of the dorsolateral subluxation score (E) calculated as
100 multiplied by the percentage of femoral head medial to the cranial acetabular rim (d) divided by the femoral head diameter (θ), d/θ ×100%).
Abbreviations: AF, acetabular fossa; An, acetabular notch; CaAE, caudal acetabular edge; CrAE, cranial acetabular edge; CrEAR, cranial effective acetabular rim; DAE, dorsal
acetabular edge; Fh, femoral head; Fv, foveal defect.
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general anesthesia, pressure is applied to the femur at the level
of the stifle while imaging the dog in ventral recumbency.43
Joints with less than 45% coverage of the femoral head
by the lateral aspect of the cranial acetabular rim have an
increased chance of developing joint changes and OA over
time compared with those with a higher percentage (.55%)
of coverage.43
Subjective radiographic evaluations are limited by
the inherent variability associated with examiners, image
quality, and differences between animals including periar-
ticular soft tissue changes and muscle atrophy. Variation in
the degree of muscle relaxation associated with sedation
or anesthesia during imaging can influence the ability to
identify joint abnormalities by as much as 50%.44 Further,
each evaluation system is distinct, so results are based on
slightly different criteria. Recently, the Orthopedic Founda-
tion for Animals score was reported to underestimate the
likelihood of developing coxofemoral joint OA compared
to the PennHIP distraction index.45 Reporting mechanisms
also vary widely in public access to individual scores for
reproduction decisions. As with any measure, radiographic
hip scores should not be used in isolation to evaluate and
predict current and future joint structure and function. It
is possible that the presence of OA at a young age may be
indicative of rapidly progressive joint disease, and, given
recognition of the genetic basis for the disease, consider-
ation of the presence and extent of CHD signs in related
individuals is likely warranted. Based on this information,
it is clear that continued efforts to identify mechanisms for
early and accurate CHD diagnosis are of utmost importance.
Adaptation of knowledge from decades of research to emerg-
ing imaging modalities will, no doubt, continue to improve
upon current standards.
Computed tomography
CT technology for pelvic imaging has improved consider-
ably over the past few decades. While radiographs remain
the primary method used to image canine coxofemoral
joints, CT is becoming increasingly popular. Using three-
dimensional CT models, a recent longitudinal study showed
that volumetric changes in the acetabulum and proximal
femur occurred in a predictable manner during skeletal
growth in a colony of dogs with coxofemoral joint laxity.46
Another study demonstrated that two-dimensional CT images
and three-dimensional models created from CT images
can be used to predict the presence of joint OA at matu-
rity.47 Two-dimensional CT measures included the percent
femoral head coverage, acetabular index, and the following
angles: acetabular anteversion, ventral, dorsal, and horizontal
acetabular sector, center edge, and horizontal toit externe
(Figure 4). Measures on three-dimensional models included
femoral head and neck volumes, femoral head and neck radii
and femoral neck angle (Figure 4). The 16-week distraction
index and center edge angle combination was the best pre-
dictor of mature OA, whereas the 32-week dorsal acetabular
sector angle and Norberg angle combination was the most
effective predictor of the presence of OA at maturity. Hence,
combined measures were the best mechanism for predicting
development of OA, and the combinations varied with age.
In a separate study, numerous measures were performed on
pelvic CT scans of beagles and mixed breed dogs at various
time points between the ages of 2 months and 1 year to assess
the relationship of the measures with joint laxity.17 The dorsal
acetabular rim angle and center distance index (the distance
between the femoral head and the center of the acetabulum,
divided by the radius of the femoral head, or the PennHIP41
distraction index) were found to be good indicators of joint
laxity and dysplastic changes.17 Magnetic resonance imag-
ing is used to evaluate the three-dimensional structure of
human articular soft tissues, and relatively recently, canine
articular soft tissues,48 but CT is best for bone structure,49
and the cost of magnetic resonance imaging for screening
may be prohibitive. As technology advances, and CT and
magnetic resonance imaging become more readily available
and affordable, use of three-dimensional imaging method-
ologies will likely become an integral part of diagnosis and
assessment of CHD.
Therapeutic management
and intervention
Conservative management
There are numerous descriptions of multifactorial systems,
with numeric, visual analog, and descriptive scales to repro-
ducibly evaluate joint pain associated with CHD.50 Many of
the assessments within the systems are subjective evalua-
tions of individual behavior or responses, and there is no
single gold standard with which to quantify hip pain in the
dog.50 While efforts continue to establish a uniform, standard
evaluation system for canine hip joint pain, those systems
that include multiple subjective and objective assessments
by individuals who are not aware of specific treatments or
conditions, are often informative.
Conservative management of CHD generally consists
of a combination of mechanisms to reduce progression of
joint damage and alleviate discomfort.51 Nonsteroidal anti-
inflammatory drugs are commonly used for pain associated
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Figure 4 Measurements and three-dimensional models for evaluating the dysplastic canine hip.
Notes: (A) Volume rendered model of the canine pelvis generated from two-dimensional computed tomography images (B and C). The blue line in (A) indicates the level
of the cross-sectional image in (B) and (C). (B) and (C) Representative measures performed on two-dimensional computed tomographic images of the canine coxofemoral
joint. Acetabular index is the ratio between the width and the depth of the acetabulum; d/w ×100. For further information see Lopez et al42 and Andronescu et al.47 For
details on these measures see Lopez et al.42
Abbreviations: AAA, acetabular anteversion angle; AI, acetabular index; CEA, center edge angle; CPC, percentage of femoral head coverage; DASA, dorsal acetabular
sector angle (dorsal coverage of the femoral head); HASA, horizontal acetabular sector angle (total acetabular coverage of the femoral head); HTEA, horizontal toit externe
angle (orientation of the acetabulum); VASA, ventral acetabular sector angle (ventral coverage of the femoral head).
with severely arthritic joints in dogs.52 Numerous studies
indicate that achieving and maintaining a healthy body
weight contributes to delayed onset and reduced clinical signs
associated with hip joint pain.4,5,53 Various food supplements
reported to alleviate signs of coxofemoral joint pain from OA
range from green-lipped mussels (Perna canaliculus)54 to
fish oil.55 Polysulfated glycosaminoglycan supplements and
injections have been recommended for prevention and treat-
ment of OA in dogs and other mammals.56–59 Intramuscular57
and intra-articular administration has also been reported,56
but responses vary.51 Alternative methods that have also been
investigated for the treatment of painful CHD joints include
acupuncture and gold bead implantation, among others. The
implantation of gold beads at acupuncture points was devel-
oped in the USA in the 1970s and implemented to a limited
degree in veterinary medicine in the 1990s for degenerative
joint disease pain.60,61 Results are mixed, with some studies
showing clinical improvement61,62 and others showing no
discernible effect.63
Maintenance of optimum body weight has long been
considered one of the most effective methods for reducing the
signs associated with dysplasia and OA.4 A lifelong dietary
restriction of 25% delayed the appearance of OA as well as the
intensity of clinical signs in Labrador Retrievers compared
with feeding ad libitum.53 Weight loss in conjunction with
physiotherapy that included transcutaneous electrical nerve
stimulation improved the clinical outcome for obese dogs
with radiographic signs of OA.64 Recently, intra-articular
botulinum toxin A was reported to reduce the pain associated
with OA based on improvements in limb use (ie, gait pat-
terns) measured with a force platform.65 At present, there are
few reports of long-term studies concerning the efficacy of
nonsurgical or conservative treatment of CHD joint changes.
These studies can be limited by the challenges of consistent
monitoring and reporting by multiple and individual owners,
as well as a wide range of disease severity and canine per-
sonalities.66 However, a recent retrospective report indicates
that conservative and nonsurgical management (ie, weight
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Schachner and Lopez
control, reduced exercise, and analgesics) of 74 dogs over the
span of 13 years did not improve quality of life as anticipated
from previous reports.66
There is significant interest in the use of regenerative
medicine to treat signs of CHD and OA; however, much of
the information reported is subjective in nature. Currently,
numerous controlled, preclinical and clinical trials are under-
way that may provide some perspective on the value of this
emerging technology. Intra-articular injection of adipose-
derived stem cells has been found to be a safe therapeutic
approach for the treatment of symptoms associated with
OA.67 Preliminary studies show that injection of adipose-
derived stem cells into affected joints may reduce clinical
signs of hip pain (ie, lameness) based on subjective clinical
evaluations67 and force platform gait analysis.68,69 A random-
ized comparison between a single intra-articular injection of
adipose-derived stem cells or plasma rich in growth factors
showed that both treatments reduced behavior associated with
pain, but that the adipose-derived stem cells appeared to be
more effective for up to 6 months post-treatment based upon
owner assessments.70 This information clearly demonstrates
that there is more work to be done on the efficacy of conserva-
tive and alternative methods to manage signs of CHD.
Surgery
Despite the prevalence of CHD, a gold standard surgical pro-
cedure has yet to be identified.71 As such, there are numerous
surgeries to prevent progression of degenerative joint changes
or alleviate pain and restore joint function.
Some surgical procedures designed to prevent onset of OA
in hips identified as being predisposed to development of OA72
include double and triple pelvic osteotomy, acetabular shelf
and excision arthroplasty, femoral osteotomy, and juvenile
pubic symphysiodesis.73 Both juvenile pubic symphysiodesis
and triple pelvic osteotomy are designed to increase femoral
head coverage by ventrolateral rotation of the acetabulum. The
juvenile pubic symphysiodesis procedure involves premature
closure of the pubic symphysis.72,74 Resulting reduction in
the pelvic inlet width causes ventrolateral rotation of the
acetabulum during pelvic growth, and is thought to result in
a 40%–46% improvement in acetabular and dorsal acetabu-
lar rim angles compared to no treatment.73–75 Juvenile pubic
symphysiodesis appears to have the best outcomes when per-
formed in puppies that are 12–16 weeks old.73 Triple pelvic
osteotomy is a much more extensive procedure, and involves
osteotomies of the ilium, pubis, and ischium to allow manual
rotation of the acetabulum for better femoral head coverage.76
The ilial osteotomy is stabilized with bone plates customized
to accommodate the rotation.77 This procedure is generally
recommended for young dogs without irreversible (or with
mild) degeneration of the coxofemoral joint.77,78 Information
about long-term outcomes of the various surgical treatments
is limited. Preliminary reports indicate that juvenile pubic
symphysiodesis and triple pelvic osteotomy minimally affect
laxity and femoral head coverage when performed at 5 months
or older72 compared with earlier reports indicating that the
procedure performed slightly earlier (15 weeks) improved
acetabular coverage of the femur.75 Mechanisms to reduce the
OA characteristic of CHD will undoubtedly improve quality of
life for affected dogs. Long-term outcomes will help identify
treatments toward this end.
Total hip replacement (Figure 5) is often applied in
advanced cases of joint degeneration and is considered a
salvage procedure.79 There are no clear guidelines for the
best time to implement total hip replacement, but the aver-
age time between onset of signs and surgery is 10 months.80
Total hip replacement procedures in dogs began in the 1970s,
and a modular system was introduced in the mid 1990s that
coupled a fixed monobloc cobalt-chromium alloy femoral
implant with an acetabular cup for cemented fixation.81
Further refinements to total hip replacement implants have
contributed to a high clinical recovery rate, with loosening of
the acetabular cup and cup wear reported as some of the most
common complications.81 More recently, cementless fixation
has been developed, and is reported to have positive results.79
As the name implies, femoral and acetabular implants are
cemented to bone for cemented total hip replacement. In
contrast, cementless fixation or uncemented implants are
designed so that the bone grows into or onto the prosthesis
without the need for cement at the bone–implant interface.
Implant loosening is reported to be less than for cemented
implants.79,82 A primary concern associated with total hip
replacement is the potential for an inflammatory response
Figure 5 Radiograph illustrating a bilateral total hip replacement.
Notes: Blue line indicates femoral implant, pink line indicates acetabular implant.
Image courtesy of Dr Jeffrey D Brourman.
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Canine hip dysplasia
to implant particulate wear debris from aseptic implant
loosening.83 Another consideration is that the persistence
of joint laxity may influence the outcomes of total hip
replacement.84 Efforts continue to improve upon available
total hip replacement implants for dogs. A hybrid system of
a cementless acetabular cup and a cemented femoral implant
has been successfully applied in dogs relatively recently.85
Hip resurfacing to replace only joint surfaces versus the
entire joint86 in dogs is under development, but clinical
trials have yet to be reported.81 Unfortunately, large-scale,
prospective randomized studies have yet to be conducted
for comparison of long-term outcomes for various surgical
procedures and nonsurgical management. Hence, individu-
alized care remains largely based on clinician preference
and experience.71
Genetics
While diagnosis and treatment of CHD are central to indi-
vidual patient care, prevention by selective breeding will help
obviate the presence of a debilitating condition in canine
companions. With this in mind, there has been significant
effort focused on identifying specific genes, genetic muta-
tions, and quantitative trait loci (regions of chromosomes
containing DNA for a specific trait), to use in conjunction
with standard imaging methods for identification of CHD
carriers.87,88 Genetic screening programs are complicated
by the polygenic nature of CHD and related OA, as well as
environmental influences on phenotypic expression. A few
promising quantitative trait loci for OA associated with
CHD89 and the CHD phenotype in German shepherds90
have been identified relatively recently. Additionally, several
chromosomal markers for CHD have been reported for a
population of cross-bred Labrador Retriever–Greyhounds.91
Notably, several specific single nucleotide polymorphisms
and positional candidate genes in dogs with CHD have been
found to correlate with genes associated with the expression
of OA and developmental dysplasia of the hip in humans.87
While the genomic underpinnings of CHD remain largely
elusive, significant progress has been made and will continue,
with expanding knowledge of the canine genome and interac-
tions among genes that influence their expression.
Future directions
Despite almost a century of research, the complex etiology
and optimal treatment paradigm for CHD remain elusive.
As originally proposed by Schnelle at a meeting of the
Veterinary Medical Society of New York City in the 1930s,92
CHD is not likely a single affliction but an array of heritable
and environmentally induced degenerative disorders that
differentially affect the morphology and function of the
canine hip. The variable phenotypic expression of CHD
makes development and implementation of standard iden-
tification procedures difficult. It may be possible to identify
specific phenotypes within the broad spectrum of CHD
similar to those of the human hip, like acetabular rim syn-
drome, acetabular retroversion, and femoral head necrosis.
The relationship between articular damage in the human
hip with morphology suggests a need to evaluate similar
relationships in the dog.93 Identification and characteriza-
tion of CHD phenotypes at the genetic, microstructural, and
macrostructural levels will likely contribute to early detec-
tion and informed breeding decisions. Another area that will
continue to promote progress in both imaging and treatment
is development of novel measures on images obtained with
contemporary imaging modalities like CT and magnetic
resonance imaging. As evidence-based assessments of CHD
prevention and treatment strategies become available, their
selection and implementation will improve and facilitate
the development of novel clinical approaches and surgical
procedures. Incremental advances in the diagnosis, treat-
ment, and prevention of the joint degeneration and pain
associated with CHD through focused research and clinical
evidence will continue to progress toward diminishing and
eradicating CHD from our canine companions.
Disclosure
The authors report no conflicts of interest in this work.
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... One of these diseases is hip dysplasia (HD). HD was first described in dogs in the 1930's (1) and in humans as early as Hippocrates (2). HD is better known as canine hip dysplasia (CHD) in dogs, and developmental dysplasia of the hip (DDH) in humans. ...
... In both species the acetabular cover of the femoral head is insufficient, either because the acetabulum (5,9,10) or the femoral head (5,9,10) is deformed, or joint laxity (2,5) is present. This disturbed femuro-acetabular relationship causes abnormally high peak forces (1,6,10) with or without joint instability and (sub)luxation (2,5,9) resulting in osteoarthritic changes (2,5,9). The body tries to counter the sequela of HD in both species by thickening and stiffening of the joint capsule (10)(11)(12) in order to reduce the laxity (11,12). ...
... Some examples of common genetic factors that influence the occurrence of HD in both species include breed (1, 6) ethnicity (29), increased anteversion angle of the femur (2,30,31), neck shaft angle of the femur (2, 31), and collagen composition (1,4). Because of these high genetic factors, family anamnesis is important for discovering HD in humans and improving breeding programs in dogs. ...
Article
Full-text available
Hip dysplasia (HD) is common in both humans and dogs. This interconnection is because humans and dogs descended from a common ancestor and therefore have a similar anatomy at micro-and macroscopic levels. Furthermore, dogs are the animals of choice for testing new treatments for human hip dysplasia and orthopedic surgery in general. However, little literature exists comparing HD between the two species. Therefore, the aim of this review is to describe the anatomy, etiology, pathogenesis, diagnostics, and treatment of HD in humans and dogs. HD as an orthopedic condition has many common characteristics in terms of etiology and pathogenesis and most of the differences can be explained by the evolutionary differences between dogs and humans. Likewise, the treatment of HD shows many commonalities between humans and dogs. Conservative treatment and surgical interventions such as femoral osteotomy, pelvic osteotomy and total hip arthroplasty are very similar between humans and dogs. Therefore, future integration of knowledge and experiences for HD between dogs and humans could be beneficial for both species.
... The Bardens test can be conducted from 8 to 9 weeks of age with 83% accuracy [19]. It should be considered that the degree of hip-joint laxity can be raised between the ages of 8 and 12 weeks due to the expansion of the joint capsule and false-positive results might be observed [20,21]. On the other hand, in juvenile dogs with severe grades of hip laxity, false-negative orthopedic examinations might be recorded because of the fibrosis of the joint capsule [20]. ...
... It should be considered that the degree of hip-joint laxity can be raised between the ages of 8 and 12 weeks due to the expansion of the joint capsule and false-positive results might be observed [20,21]. On the other hand, in juvenile dogs with severe grades of hip laxity, false-negative orthopedic examinations might be recorded because of the fibrosis of the joint capsule [20]. Thus, due to the possibility of false-negative or false-positive results, a combination of the physical and radiographic examinations is recommended [22][23][24]. ...
Article
Full-text available
Canine hip dysplasia is a complex and multifactorial disease. The early diagnosis of dysplastic dogs under one year of age helps veterinarians to plan proper preventive/therapeutic methods. Having an accurate screening method increases the chance of the early detection of dysplasia. The goal of our study was to assess the inter-observer reliability of eight radiographic parameters in four-month-old Rottweilers. Radiographs of the 28 Rottweilers were investigated by five experienced observers. The radiographs were taken in ventrodorsal view with extended legs, frog-leg ventrodorsal view, distraction view, and dorsal acetabular rim view. Four quantitative parameters such as Norberg angle (NA), distraction index (DI), dorsal acetabular rim slope (DARS), and center edge angle (CEA) and four qualitative parameters such as sclerosis of the cranial acetabular rim (SCAR), location of the center of the femoral head (LCFH), grading of the degenerative joint disease (GDJD), and grading of the dorsal acetabular rim (GDAR) were evaluated. High inter-observer agreements were recorded for quantitative values, whereas the inter-observer agreement of the qualitative parameters was low. It can be deduced that the evaluated quantitative parameters are reliable, and a combination of these methods with clinical examinations might increase the accuracy of the examinations.
... Orthogonal radiographs and CT of the pelvis and hips were made at − 6, 0, + 6, + 12, + 26 weeks from the implantation ( Table 1) and parameters such as the center-edge (CE)-angle 18 were assessed by a board-certified veterinary radiologist. Subsequently, the CT-scans were uploaded into image analysis software Mimics (Medical v20, Materialise, Leuven, Belgium) to calculate the percentage of femoral head coverage by using multiplanar reconstruction 19 . ...
... After surgery, the mean CE-angle of the treated hips improved, due to a combination of femoral head medialization and an increase in femoral head coverage by the acetabulum and implant (Fig. 4). The mean intervention side CE-angle increased to 119° (117°-120°), which is within the normal range 18 . The mean total femoral head coverage for the intervention hips increased from 46% (range 41-50%) preoperatively to 60% (58-62%) postoperatively (Table 2 and Fig. 4). ...
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The concept of a novel patient-specific 3D-printed shelf implant should be evaluated in a relevant large animal model with hip dysplasia. Therefore, three dogs with radiographic bilateral hip dysplasia and a positive subluxation test underwent unilateral acetabular augmentation with a 3D-printed dog-specific titanium implant. The contralateral side served as control. The implants were designed on CT-based pelvic bone segmentations and extended the dysplastic acetabular rim to increase the weight bearing surface without impairing the range of motion. Outcome was assessed by clinical observation, manual subluxation testing, radiography, CT, and gait analysis from 6 weeks preoperatively until termination at 26 weeks postoperatively. Thereafter, all hip joints underwent histopathological examination. The implantation and recovery from surgery was uneventful. Clinical subluxation tests at the intervention side became negative. Imaging showed medialization of the femoral head at the intervention side and the mean (range) CE-angle increased from 94° (84°–99°) preoperative to 119° (117°–120°) postoperative. Gait analysis parameters returned to pre-operative levels after an average follow-up of 6 weeks. Histology showed a thickened synovial capsule between the implant and the femoral head without any evidence of additional damage to the articular cartilage compared to the control side. The surgical implantation of the 3D shelf was safe and feasible. The patient-specific 3D-printed shelf implants restored the femoral head coverage and stability of dysplastic hips without complications. The presented approach holds promise to treat residual hip dysplasia justifying future veterinary clinical trials to establish clinical effectiveness in a larger cohort to prepare for translation to human clinic.
... Hip dysplasia is a biomechanical disease characterized by the incompatibility of the hip joint, which occurs under the influence of hereditary and environmental factors, and can be seen in all carnivores, especially in dogs. It was first described by Schnelle in 1935 as bilateral luxation of the coxofemoral joint (Gınja et al. 2006, Karabaglı et al. 2014, Schachner and Lopez 2015, Bostancı and Demirkan 2017, Polat 2021. ...
... Dogs with hip dysplasia are known to show clinical signs such as lameness in their hind legs, muscular atrophy, exercise intolerance, and rabbit walking (Deny et al. 2000, Dassler 2002, Schachner and Lopez 2015. Deformations and inflammations in the musculoskeletal system can cause differences in hematocrit (HCT) and serum biochemical parameters. ...
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In this study, it was aimed to investigate the effect of hip dysplasia on some biochemical parameters, oxidative stress factors and hematocrit values in dogs. Hematocrit values (HTC), serum calcium (Ca), phosphorus (P) levels, serum alkaline phosphatase (ALP), creatine kinase (CK) activities and oxidative stress factors were evaluated in a total of 27 dogs with healthy hip joints (n: 11) and hip dysplasia (n: 16). There was no statistically significant difference between the two groups in terms of HCT, Ca and P values (p˃0.05). ALP and CK activities were found to be statistically significantly increased in the group with hip dysplasia compared to the control group with a healthy hip joint (p˂0.05). While malondialdehyde (MDA) level, one of the oxida-tive stress factors, was increased in the group with hip dysplasia, decreased glutathione (GSH) levels, catalase (CAT) and glutathione peroxidase (GSH-Px) activities were significantly decreased. There was no significant difference between the two groups in terms of superoxide dismutase (SOD) level. As a result, it was determined that oxidative stress factors differ in dogs with hip dysplasia compared to dogs with the healthy hip joint.
... Occasionally, in dog there is an abnormal development of bone structures on the hip joint, followed by synovial inflammation and articular cartilage damage, resulting in inadequate hip development with different levels of incongruency between the femoral head and the acetabulum. This condition is commonly denominated as hip dysplasia (HD) [3]. ...
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... Various diseases, such as osteoarthritis, intervertebral disc disease and cancer are common in companion animals and usually result in chronic pain that affects animals' wellbeing (1,2). Nonsteroidal anti-inflammatory drugs (NSAIDs) are commonly used for analgesia of chronic pain in dogs (3)(4)(5) but may fail to control pain and can be associated with adverse effects (6,7). ...
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... In addition, studies are still necessary for canine hip dysplasia, a disease that can affect the gait and has a high prevalence in large-and giant-breed dogs [21,22]. Hip dysplasia is commonly diagnosed by clinical signs and imaging studies, more frequently using hip-extended radiographs, but the relationship between the radiographic changes and clinical signs may be inconsistent [23]. However, a study of sEMG of the vastus lateralis, biceps femoris, and gluteus medius muscles in dogs on walking showed that those with hip osteoarthritis had mean activity of the muscles significantly decreased during the early swing phase [5]. ...
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Accelerometers may be used as a tool for objective analysis of kinetic and/or temporospatial gait parameters; however, only a few studies have been done in small animals. Therefore, this study analysed surface electromyography (sEMG) signals related to inertial sensors (accelerometry), aiming to create a reproducible standard in dogs. The hypothesis was that the combined use of an accelerometer and sEMG sensors could be used to identify the phases of the gait cycle and that the standard data established in healthy dogs could be used to compare data obtained from dogs with hip dysplasia. These signs were obtained from two different muscles, the biceps femoris and vastus lateralis muscles, from two breeds of dogs (Labrador retriever and golden retriever), during a walking gait at a controlled velocity. After signal processing, a second-order low-pass Butterworth filter with a cut-off frequency of 6 Hz was used, and an algorithm was applied to determine a threshold value for the gait cycle phases. Then, correlations between signals from both transducers were determined. Data relating to percent muscle activity, correlation and asymmetric functions, stance time and swing during the gait cycle in healthy dogs were generated after signal processing. Signals collected from dogs with hip dysplasia fell outside of the reference intervals established in healthy dogs. In conclusion, the methods applied for signal analysis and processing allowed the identification of structures of muscular activity during the gait cycle and the establishment of normal distribution values in healthy dogs.
... There has been a significant effort on identifying specific genes, mutations, and quantitative trait loci, to use in conjunction with standard imaging methods for the identification of canine hip dysplasia carriers (Zhou et al.,) [14] , (Zhu et al.,) [15] . As evidence-based assessments of canine hip dysplasia become available, their selection and implementation will improve and facilitate the development of novel clinical approaches and surgical procedures (Schachner et al.,) [11] . These trends should be confirmed by a larger genetic study on the molecular level (Kasarda et al.,) [6] . ...
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At the time of purchasing a dog, should observe that they have hip dysplasia or not. The combined application of the quantitative and qualitative methods could help in the selective breeding of dogs. A healthy diet and avoiding unusual playing could free them from this hip dysplasia. Inbreeding ensures the fixation of such traits the chance of the following problem. In severe cases, novel clinical approaches and surgical procedures could be applicable.
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Hip dysplasia (HD) is one of the most common hereditary orthopaedic diseases in dogs, with serious implications for the quality of life of the affected animals. Radiographic screening is essential for the selection of breeding stock in some at-risk breeds, and radiography is also used in the diagnosis of clinical HD cases. A definitive diagnosis of HD is based on radiographic examination, and the most commonly used view is the ventrodorsal hip extended projection, sometimes in combination with various hip stress-based techniques. Radiographic images require high quality positioning and dogs are usually anesthetized and often manually restrained to facilitate optimal positioning. The ‘as low as reasonably achievable’ (ALARA) principle used in human radioprotection is not always fulfilled in veterinary practice, except in the UK, where human exposure to ionizing radiation in veterinary medicine is strictly regulated. While each dose of ionizing radiation is small, doses accumulate over a lifetime, which can eventually result in substantial radiation exposure. Therefore, manual restraint should be avoided and mechanical immobilization, sedation or general anaesthesia should be used. This review examines the biological effects of human exposure to ionizing radiation and common sources of veterinary exposure. The diagnostic quality of imaging methods for the diagnosis of canine HD is compared between manually restrained and hands-free dog positioning. Hands-free radiographic techniques are available to assess hip laxity, degenerative joint changes and hip osseous structure while preserving image quality, and can be used to select animals for breeding or for the diagnosis of HD.
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Stem cells isolated from adipose tissue show great therapeutic potential in veterinary medicine, but some points such as the use of fresh or cultured cells and route of administration need better knowledge. This study aimed to evaluate the effect of autologous stromal vascular fraction (SVF, n = 4 ) or allogeneic cultured adipose-derived stem cells (ASCs, n = 5 ) injected into acupuncture points in dogs with hip dysplasia and weak response to drug therapy. Canine ASCs have proliferation and differentiation potential similar to ASCs from other species. After the first week of treatment, clinical evaluation showed marked improvement compared with baseline results in all patients treated with autologous SVF and three of the dogs treated with allogeneic ASCs. On days 15 and 30, all dogs showed improvement in range of motion, lameness at trot, and pain on manipulation of the joints, except for one ASC-treated patient. Positive results were more clearly seen in the SVF-treated group. These results show that autologous SVF or allogeneic ASCs can be safely used in acupoint injection for treating hip dysplasia in dogs and represent an important therapeutic alternative for this type of pathology. Further studies are necessary to assess a possible advantage of SVF cells in treating joint diseases.
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Purpose: The aim of this study was to compare the efficacy and safety of a single intra-articular injection of adipose mesenchymal stem cells (aMSCs) versus plasma rich in growth factors (PRGF) as a treatment for reducing symptoms in dogs with hip osteoarthritis (OA). Methods: This was a randomized, multicenter, blinded, parallel group. Thirty-nine dogs with symptomatic hip OA were assigned to one of the two groups, to receive aMSCs or PRGF. The primary outcome measures were pain and function subscales, including radiologic assessment, functional limitation and joint mobility. The secondary outcome measures were owners' satisfaction questionnaire, rescue analgesic requirement and overall safety. Data was collected at baseline, then, 1, 3 and 6 months post-treatment. Results: OA degree did not vary within groups. Functional limitation, range of motion (ROM), owner's and veterinary investigator visual analogue scale (VAS), and patient's quality of life improved from the first month up to six months. The aMSCs group obtained better results at 6 months. There were no adverse effects during the study. Our findings show that aMSCs and PRGF are safe and effective in the functional analysis at 1, 3 and 6 months; provide a significant improvement, reducing dog's pain, and improving physical function. With respect to basal levels for every parameter in patients with hip OA, aMSCs showed better results at 6 months.
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Background Regenerative medicine using Mesenchymal Stem Cells (MSC) alone or combined with Plasma Rich in Growth Factors (PRGF) is a rapidly growing area of clinical research and is currently also being used to treat osteoarthritis (OA). Force platform analysis has been consistently used to verify and quantify the efficacy of different therapeutic strategies for the treatment of OA in dogs including MSC associated to PRGF, but never with AD-MSC alone. The aim of this study was to use a force platform to measure the efficacy of intraarticular ADMSC administration for limb function improvement in dogs with severe OA. Results Ten lame dogs with severe hip OA and a control group of 5 sound dogs were used for this study. Results were statistically analyzed to detect a significant increase in peak vertical force (PVF) and vertical impulse (VI) in treated dogs. Mean values of PVF and VI were significantly improved within the first three months post-treatment in the OA group, increasing 9% and 2.5% body weight, respectively, at day 30. After this, the effect seems to decrease reaching initial values. Conclusion Intraarticular ADMSC therapy objectively improved limb function in dogs with hip OA. The duration of maximal effect was less than 3 months.
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A double-blind, randomised, controlled, multicentre field study was conducted to compare the safety and efficacy of firocoxib chewable tablets and carprofen tablets in 218 dogs with osteoarthritis. Firocoxib is a non-steroidal anti-inflammatory drug with more than 350-fold selectivity in dogs for the inducible isoform of the enzyme cyclo-oxygenase-2. The efficacy, tolerance and ease of administration of firocoxib (5 mg/kg/day) and carprofen (4 mg/kg/day) were assessed by the owners and the attending veterinarians during 30 days of treatment. The efficacy was assessed in terms of the dogs' overall scores at the end of the treatment, based on the veterinarians' assessment of lameness, pain on manipulation/palpation, range of motion, and joint swelling; 92.5 per cent of the dogs treated with firocoxib and 92.4 per cent of the dogs treated with carprofen had improved. The reduction in lameness in the dogs treated with firocoxib was significantly greater than in the dogs treated with carprofen. The owners' evaluations were that 96.2 per cent of the dogs treated with firocoxib and 92.4 per cent of the dogs treated with carprofen had improved, and this difference was statistically significant.
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A “double blinded” prospective study was undertaken to determine whether gold bead implantation acupuncture alleviates lameness and pain in dogs, affected by moderate to severe hip dysplasia. Nineteen large-breed adult dogs, of various breeds with clinical and radiographic evidence of hip dysplasia, were randomly assigned to the acupuncture or the placebo group. The acupuncture treatment with gold bead implantation was performed by a licensed acupuncturist. Objective data were acquired, in the gait analysis laboratory, using kinetic and kinematic parameters before and at one and three months after treatment. In the acupuncture group there was a decrease in vertical and peak vertical impulse formation at one month, which indicated an increase in lameness, without any significant difference between groups at three months post-treatment. Subjective data were gathered by radiographs as well as serial complete physical examinations by an experienced clinician and an owner questionnaire, before and at one and three months after treatment. Subjective grading of hip dysplasia radiographs did not show any difference in severity between the two groups. According to the physical examination, one dog in the acupuncture group improved, five stayed the same and three worsened. In the placebo group two dogs improved, four stayed the same and three worsened. According to the questionnaire, three dogs in the acupuncture group improved, four stayed the same and two worsened. In the placebo group three dogs improved and six stayed the same. Serial blood analyses were performed and the results were within normal limits at all times.
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Hip dysplasia is a potentially debilitating orthopaedic disease in which laxity of the coxofemoral joint often leads to secondary osteoarthritis, a reduction in joint function and pain. It has been recognised for many years as being of particular importance in pedigree dogs, especially in larger breeds, and is known to be partly governed by genetic factors. In order to try to control canine hip dysplasia and to reduce its incidence, a number of radiographic screening programmes have been developed worldwide. In 1983, a scheme was established by the British Veterinary Association and supported by the Kennel Club to examine radiographs of dogs' hips by assessing different anatomical features and giving them a numerical score. This article describes the process of scoring in this scheme, explains how to interpret the score and gives advice on the use of hip scores in the selection of breeding animals.
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Objective: To evaluate associations of measures assessed by radiography, 2-D CT, and 3-D CT of the hip joints of immature dogs with osteoarthritis in the same joints at maturity. Animals: 46 hound-type dogs from a colony predisposed to osteoarthritis. Procedures: Images of hip joints (1/dog) were obtained at 16, 32, and 104 weeks of age. Radiographic measures included Norberg angle, distraction index, and osteoarthritis score. Two-dimensional CT measures included acetabular index, percentage of femoral head coverage, and center edge, horizontal toit externe, acetabular anteversion, and ventral, dorsal, and horizontal acetabular sector angles. Three-dimensional CT measures were femoral head and neck volume, femoral neck angle, and femoral head and neck radius. Differences among measures at 16 and 32 weeks in dogs with different osteoarthritis scores at later time points, relationships among variables at each time point, and relationships of single and combined measures with the presence of osteoarthritis at 104 weeks were evaluated. Results: The 16- and 32-week distraction index, center edge angle, dorsal acetabular sector angle, horizontal acetabular sector angle, percentage of femoral head coverage, acetabular index, and Norberg angle and the 32-week femoral neck angle varied significantly with osteoarthritis severity at 104 weeks. Presence of osteoarthritis in mature dogs was most strongly associated with 16-week combined measures of distraction index and center edge angle and 32-week combined measures of dorsal acetabular sector angle and Norberg angle. Conclusions and clinical relevance: Changes in hip joint morphology associated with radiographic signs of osteoarthritis were detectable as early as 16 weeks of age and varied with osteoarthritis severity in adult dogs. The use of combined hip joint measures may improve early identification of dogs predisposed to hip joint osteoarthritis.
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Purpose The aim of this study was to obtain data on chondral damage and compare the damage patterns of various hip disorders. Methods Data were collected at 100 consecutive arthroscopies, and chondral lesions were recorded on anatomic articular maps divided into different anatomical zones. This geographic zone method made it possible to analyze the ICRS grade and location in relation to the hip morphology. Results The distribution and degree of the chondral defects showed a hip morphology-specific pattern. On the acetabular side, there were high incidences of full-thickness defects in the anterior–superior zone and the middle superior zone in patients with femoroacetabular impingement (FAI) (zone 2: 25.4 % grade 3, 35.5 % grade 4; zone 3: 20.3 % grade 3, 37.2 % grade 4) and borderline dysplasia (zone 2: 31.2 % grade 3, 12.5 % grade 4; zone 3: 18.7 % grade 3, 25 % grade 4). However, in patients with joint laxity, partial-thickness defects were dominant (zone 2: 50 % grade 1, 15 % grade 2; zone 3: 40 % grade 1). In patients with acetabular dysplasia, full-thickness defects extended even to the posterior superior zone (zone 4: 80 % grade 4). On the femoral head side, the incidence of full-thickness cartilage injuries was high in patients with FAI and borderline dysplasia compared to those with joint laxity and acetabular dysplasia. Conclusion Evaluation of chondral damage using the geographic zone method showed that the pattern of cartilage damage was influenced by hip morphology. Understanding of hip disorder-specific chondral damage patterns may be useful for the development of arthroscopic classification of hip disorders and may lead to the establishment of treatment guidelines. Level of evidence Diagnostic study, Level III.