Title: Canine hip dysplasia

{{short description|Joint abnormality in dogs}}
{{more citations needed|date=July 2022}}
{{About|the disease in dogs|the disease in humans|Hip dysplasia|the disease in other animals|Hip dysplasia#Other animals}}
{{Use mdy dates|date=September 2021}}
[[File:Bilateral hip dysplasia.JPG|thumb|Hip dysplasia in a Labrador Retriever]]
[[Image:Normal canine hips.JPG|thumb|Normal hips, for comparison]]

In dogs, '''hip dysplasia''' is an abnormal formation of the hip socket that, in its more severe form, can eventually cause lameness and arthritis of the joints. It is a genetic (polygenic) trait that is affected by environmental factors. It is common in many dog breeds, particularly the larger breeds, and is the most common single cause of arthritis of the hips.&lt;ref name=&quot;workingdogs.com&quot;&gt;{{cite web |author=Workingdogs.com |title=Canine hip dysplasia |url=https://www.petshelps.com/dog-hip-dysplasia-causes-symptoms-and-treatments/ |access-date=August 18, 2013 |publisher=Workingdogs.com}}&lt;/ref&gt;

==Overview==
===Normal hip anatomy===
In the normal [[anatomy]] of the [[hip]] joint, the almost spherical end of the [[femur]] head (the caput, or caput ossis femoris) fits into the [[acetabulum]] (a concave socket located in the [[pelvis]]). The bony surfaces of the femur head and of the acetabulum are covered by cartilage. While bones provide the strength necessary to support body weight, cartilage ensures a smooth fit and a wide range of motion. Normal hip function can be affected by congenital conditions such as dysplasia, trauma, and by acquired diseases such as [[osteoarthritis]] and [[rheumatoid arthritis]].{{cn|date=August 2024}}

===Dysplastic hip anatomy===
The hip could have major contractions from dysplasias. The caput is not deeply and tightly held by the acetabulum. Instead of being a snug fit, it is a loose fit, or a partial fit. Secondly, the caput or acetabulum are not smooth and round, but are misshapen, causing abnormal wear and tear or friction within the joint as it moves.&lt;ref name=&quot;:4&quot;&gt;{{Cite web|url=http://vcahospitals.com/know-your-pet/hip-dysplasia-in-dogs|title=Hip Dysplasia in Dogs|website=vca_corporate|language=en|access-date=December 22, 2019}}&lt;/ref&gt;
The body reacts to this in several ways. First, the joint is continually repairing itself and laying down new [[cartilage]]. However, cartilage repair is a relatively slow process, the tissue being [[avascular]], so the joint may suffer degradation due to the abnormal wear and tear, or may not support the body weight as intended. The joint becomes [[inflammation|inflamed]] and a cycle of cartilage damage, inflammation and pain commences. This is a [[positive feedback|self-fueling]] process, in that the more the joint becomes damaged, the more damage it will cause to the surrounding tissues and bones. The inflammation also causes further damage. The bones of the joint may also develop [[osteoarthritis]], visible on a [[radiograph]] as small outcrops of bone, which further degrade the joint.&lt;ref&gt;{{Cite web|url = https://www.youtube.com/watch?v=ntwLK6kHnbo|title = Ask The Expert Dr. Randall - Hip Dysplasia In Dogs|date = March 23, 2014|access-date = November 10, 2015|website = Youtube|publisher = Flexpet|last = Randall|first = D.}}&lt;/ref&gt; Osteoarthritis is a degenerative disease marked by the breakdown of cartilage between joints resulting in painful bone-to-bone contact.&lt;ref&gt;{{Cite journal|last1=Connor|first1=J.R.|last2=LePage|first2=C.|last3=Swift|first3=B.A.|last4=Yamashita|first4=D.|last5=Bendele|first5=A.M.|last6=Maul|first6=D.|last7=Kumar|first7=S.|title=Protective effects of a cathepsin K inhibitor, SB-553484, in the canine partial medial meniscectomy model of osteoarthritis|journal=Osteoarthritis and Cartilage|volume=17|issue=9|pages=1236–1243|doi=10.1016/j.joca.2009.03.015|pmid=19361586|year=2009|doi-access=free}}&lt;/ref&gt;

The underlying deformity of the joint may get worse over time, or may remain static. A dog may have good radiographs and yet be in pain, or may have very poor radiographs and have no apparent pain issues. The hip condition is only one factor to determine the extent to which dysplasia is causing pain or affecting the quality of life. In mild to moderate dysplasia it is often the secondary effects of abnormal wear and tear or arthritis, rather than dysplasia itself, which is the direct causes of visible problems.&lt;ref name=&quot;:5&quot;&gt;{{Cite web|url=https://www.ofa.org/diseases/hip-dysplasia|title=What is canine hip dysplasia?|date=2018|website=Orthopedic Foundation for Animals|access-date=December 22, 2019}}&lt;/ref&gt;

===Causes and effects===
[[File:Hip dysplasia gait.jpg|thumb|right|300px|A Labrador Retriever standing with hind legs close together to compensate for hip dysplasia]]
Hip dysplasia may be caused by a femur that does not fit correctly into the pelvic socket, or poorly developed muscles in the pelvic area. Large and giant breeds are most susceptible to hip dysplasia (possibly due to the [[body mass index]] (BMI) of the individual animal),&lt;ref name=&quot;Comhaire 2008&quot;&gt;{{cite journal|last1=Comhaire|first1=F.H.|last2=Snaps|first2=F.|title=Comparison of two canine registry databases on the prevalence of hip dysplasia by breed and the relationship of dysplasia with body weight and height.|journal=American Journal of Veterinary Research|date=March 2008|volume=69|issue=3|pages=330–3|doi=10.2460/ajvr.69.3.330|pmid=18312130|doi-access=free}}&lt;/ref&gt; though many other breeds can suffer from it. The [[Orthopedic Foundation for Animals]] maintains a list of top 100 breeds affected.&lt;ref&gt;{{cite web|title=Hip Dysplasia by Breed|url=http://www.offa.org/stats_hip.html|archive-url=https://web.archive.org/web/20101019034631/http://www.offa.org/stats_hip.html|archive-date=October 19, 2010|publisher=Orthopedic Foundation for Animals|access-date=April 30, 2017|year=2016}}&lt;/ref&gt;

To reduce pain, the animal will typically reduce its movement of that hip. This may be visible as &quot;bunny hopping&quot;, where both legs move together, or less dynamic movement (running, jumping), or stiffness. Since the hip cannot move fully, the body compensates by adapting its use of the [[Vertebral column|spine]], often causing spinal, [[stifle joint|stifle]] (a dog's knee joint), or soft tissue problems to arise.{{cn|date=August 2024}}

The causes of hip dysplasia are considered heritable, but new research conclusively suggests that environment also plays a role.&lt;ref&gt;{{cite web|url=https://www.sciencedaily.com/releases/2012/03/120326112842.htm/ |title=A number of environmental factors can affect the incidence of hip dysplasia in dogs |publisher=Veths.no |date=March 26, 2012 |access-date=March 2, 2023}}&lt;/ref&gt; To what degree the causality is genetic and what portion environmental is a topic of current debate. [[Neutering]] a dog, especially before the dog has reached an age of full developmental maturity, has been shown to almost double the chance he or she will develop hip dysplasia versus intact dogs or dogs that were neutered after reaching adulthood.&lt;ref&gt;{{cite journal | last1 = Torres | last2 = de la Riva | first2 = G. | last3 = Hart | first3 = B.L. | last4 = Farver | first4 = T.B. | last5 = Oberbauer | first5 = A.M. | last6 = Messam | first6 = L.L.M. | last7 = Willits | first7 = N. | display-authors = 4 | year = 2013 | title = Neutering Dogs: Effects on Joint Disorders and Cancers in Golden Retrievers | journal = PLOS ONE | volume = 8 | issue = 2| article-number = e55937 | doi = 10.1371/journal.pone.0055937 | pmid = 23418479 | pmc = 3572183 | bibcode = 2013PLoSO...855937T | doi-access = free }}&lt;/ref&gt; Other environmental influences include overweight condition, injury at a young age, overexertion on the hip joint at a young age, ligament tear at a young age, or repetitive motion on forming joint (e.g. jogging with puppy under the age of 1 year). As current studies progress, greater information may help provide procedures to effectively reduce the occurrence of this condition.{{cn|date=August 2024}}

It is most common in medium-large pure bred dogs, such as [[Newfoundland (dog)|Newfoundland]]s, [[German Shepherd Dog]]s, [[retriever]]s (such as [[Labrador retriever|Labrador]]s, [[Nova Scotia Duck Tolling Retriever|Toller]]s, or [[Golden retriever|Golden]]s), [[Rottweiler]]s and [[Mastiff]]s, but also occurs in some smaller breeds such as [[spaniel]]s and [[pug]]s.&lt;ref&gt;{{Cite web|url=https://www.akc.org/expert-advice/health/hip-dysplasia-in-dogs/|title=Hip Dysplasia in Dogs: Causes, Symptoms &amp; Treatment|website=American Kennel Club|language=en|access-date=December 22, 2019}}&lt;/ref&gt;

==Clinical detection and testing==
===Symptoms===
{{Redirect-distinguish|Morgan's line|Dennie–Morgan fold}}
[[File:Tchén splawnaedje hanche.jpg|thumb|Atrophy of thigh muscle after a two-year evolution of hip dysplasia]]

Dogs with hip dysplasia may exhibit the following signs and symptoms:&lt;ref name=&quot;:5&quot; /&gt;

*Decreased activity 
*Decreased range of motion
*Difficulty or reluctance rising, jumping, running, or climbing stairs
*Lameness in the hind end
*Looseness in the joint
*Narrow stance
*Swaying, &quot;bunny hopping&quot; gait
*Grating in the joint during movement     
*Loss of thigh muscle mass
*Noticeable enlargement of the shoulder muscles as they compensate for the hind end   
*Pain
*Stiffness or soreness after rising from rest
*[[Subluxation]] or [[joint dislocation|dislocation]] of the hip joint
*Caudolateral curvilinear [[osteophyte]], sometimes called Morgan's line, a thickened osteophyte on the [[caudal (anatomical term)|caudal]] aspect of the [[femoral neck]]&lt;ref&gt;{{cite journal |last1=Kishimoto |first1=M. |last2=Pae |first2=S.-H. |last3=Muroya |first3=N. |last4=Watarai |first4=H. |last5=Anzai |first5=H. |last6=Lee |first6=K.-J. |last7=Shimizu |first7=J. |last8=Sasaki |first8=M. |last9=Yamada |first9=K. |title=The relationship between the size of caudolateral curvilinear osteophyte of the canine femoral neck and the radiographic view |journal=Journal of Veterinary Science |year=2010 |volume=11 |issue=1 |pages=89–91 |doi=10.4142/jvs.2010.11.1.89 |pmid=20195071 |pmc=2833436}}&lt;/ref&gt;

Affected dogs can show clinical signs as early as seven months of age, but most do not until one to two years of age.&lt;ref name=&quot;:4&quot; /&gt; In part this is because the underlying hip problem may be mild or severe, worsening or stable, and the body may be more or less able to keep the joint in repair well enough to cope.{{cn|date=August 2024}}

===Diagnosis===
Hip dysplasia is diagnosed with radiographs of the pelvis.
It is also common to [[X-ray]] the spine and legs, as well as the hips, since [[soft tissue]]s can be affected by the extra strain of a dysplastic hip, or there may be other undetected factors such as [[neurology|neurological]] issues (e.g. [[nerve]] damage) involved.{{cn|date=August 2024}}

===Other conditions with similar symptoms===
The following conditions can give symptoms very similar to hip dysplasia, and should be ruled out during diagnosis:
* [[Cauda equina syndrome]] (i.e. lower back problems){{cn|date=August 2024}}
* Cranial (anterior) [[Cruciate ligament]] tears{{cn|date=August 2024}}
* Other rear limb arthritic conditions&lt;ref name=&quot;petsurgery.com&quot;&gt;{{Cite web|url=http://www.petsurgery.com/totalhipreplacement.html|title=Total Hip Replacement|date=2006|website=Southern California Veterinary Referral Group|archive-url=https://web.archive.org/web/20060613175606/http://www.petsurgery.com/totalhipreplacement.html |archive-date=June 13, 2006 }}&lt;/ref&gt;
* [[Osteochondritis dissecans]] and [[elbow dysplasia]] in the forelimbs are difficult to diagnose as the animal may only exhibit an unusual gait, and may be masked by, or misdiagnosed as, hip dysplasia.&lt;ref name=&quot;Ch.84OCD&quot;&gt;{{cite book |author1=Lenehan, T.M.|author2=Van Sickle, D.C. |editor1=Nunamaker, D.M.|editor2=Newton, C.D. |chapter=Chapter 84: Canine osteochondrosis|chapter-url=http://cal.vet.upenn.edu/projects/saortho/chapter_84/84mast.htm|title=Textbook of small animal orthopaedics|url=http://cal.vet.upenn.edu/projects/saortho/index.html|publisher=Lippincott|location=Philadelphia|year=1985|isbn=978-0-397-52098-5}}&lt;/ref&gt;

A dog may misuse its rear legs, or adapt its gait, to compensate for pain in the ''forelimbs'', notably [[osteoarthritis]], [[osteochondritis]] (OCD) or [[elbow dysplasia|shoulder or elbow dysplasia]], as well as pain in the hocks and stifles or spinal issues. It is important to rule out other joint and bodily issues before concluding that only hip dysplasia is present. Even if some hip dysplasia is present, it is possible for other conditions to co-exist or be masked by it.{{cn|date=August 2024}}

==Treatment==
There is no complete cure, although there are many options to alleviate the clinical signs. The aim of treatment is to enhance quality of life.{{cn|date=August 2024}}

Most dogs with hip dysplasia do not need surgery as they do very well with a home physical therapy program, keeping trim and strong, and using pain medication as needed.&lt;ref name=&quot;:4&quot; /&gt;

If the problem cannot be controlled with medications, then often surgery is considered. There are traditionally two types of surgery - those which reshape the joint to reduce pain or help movement, and [[hip replacement (animal)|hip replacement]] which completely replaces the damaged hip with an artificial joint, similar to [[hip replacement|human hip replacements]].{{cn|date=August 2024}}

===Non-surgical interventions===
Non surgical intervention is dependent on many factors including age, weight, degree of hip laxity, lifestyle of the owner and their tolerance for the cost incurred for medication and physical therapy.&lt;ref name=&quot;:4&quot; /&gt;

==== Maintenance of minimal body weight ====
Weight control is often &quot;the single most important thing that we can do to help a dog with arthritis,&quot; and &quot;reducing the dog's weight is enough to control all of the symptoms of arthritis in many dogs.&quot;&lt;ref name=&quot;vetrica_arthritis2&quot;&gt;{{cite web|url=http://www.vetrica.com/care/dog/arthritis.shtml|title=Arthritis in the Dog|date=February 9, 2004|publisher=Vetrica.com|access-date=August 18, 2013|archive-url=https://web.archive.org/web/20140204052845/http://www.vetrica.com/care/dog/arthritis.shtml|archive-date=February 4, 2014}}&lt;/ref&gt; With weight control, the goal is to prevent the dog from becoming overweight to reduce mechanical stresses applied to the hip joints. In general terms, the ribs should be easily palpated and there should be an indentation in front of the hip bones.&lt;ref name=&quot;:5&quot; /&gt;

==== Exercise routine ====
Reasonable exercise stimulates cartilage growth and reduces degeneration,&lt;ref name=&quot;vetrica_arthritis2&quot; /&gt; and also regular walks taken in the early stages of dysplasia can help prevent loss of muscle mass to the hips. Exercise should fit an individual dog's maximum intensity level with the goal to maintain muscle tone and cardiovascular function without causing pain, stiffness, and inflammation to the joint. Exercise also improves joint range of motion which in turn keeps the dog more comfortable. Swimming, because it is a non-weight bearing exercise, can be a very useful means of maintaining muscle tone and range of motion without placing concussive forces on the joint, though swimming is primarily a front-legged exercise.&lt;ref name=&quot;:5&quot; /&gt;

==== Medication ====
Medication can reduce pain and discomfort, and also reduce damaging inflammation.&lt;ref name=&quot;vetrica_arthritis2&quot; /&gt; Most often, medication consists of a [[non-steroidal anti-inflammatory drug]] (NSAID), which doubles as an anti-inflammatory and painkiller. Typical NSAIDs used for hip dysplasia include [[carprofen]] and [[meloxicam]] (often sold as Rimadyl and Metacam respectively).&lt;ref&gt;{{Cite web|url=https://toegrips.com/medicine-hip-dysplasia-dogs/|title=Helpful Medicine for Hip Dysplasia in Dogs. 10 Tips for Treating Hip Dysplasia without Surgery|date=February 6, 2019|website=Dr. Buzby's ToeGrips for Dogs|language=en-US|access-date=December 22, 2019}}&lt;/ref&gt; Both are used to treat arthritis resulting from dysplasia, although other NSAIDs such as [[tepoxalin]] (Zubrin) and [[prednoleucotropin]] (&quot;PLT&quot;, a combination of [[cinchophen]] and [[prednisolone]]) are sometimes prescribed.{{cn|date=August 2024}}

==== Diet supplementation ====
Incorporating [[omega-3 fatty acid]]s such as [[docosahexaenoic acid]] (DHA) and [[eicosapentaenoic acid]] (EPA) into the diet can result in improved symptoms of the disease. Omega-3 fatty acids can help decrease inflammation that occurs from osteoarthritis, as well as improve the locomotion of dogs who have the disease. EPA and DHA can be supplemented into the diet through fish oils.{{cn|date=August 2024}}

[[Glucosamine]] and [[chondroitin sulfate]] are [[nutraceutical]]s that can also be added into the diet to help treat osteoarthritis caused by hip dysplasia. Both nutraceuticals help with improvement of cartilage, joint health and repairing of tissues. A glucosamine-based nutritional supplement may give the body additional raw materials used in joint repair. Glucosamine can take 3–4 weeks to start showing its effects, so the trial period for medication is usually at least 3–5 weeks. In vitro, glucosamine has been shown to have negative effects on cartilage cells.&lt;ref&gt;{{cite journal |author1=Terry, D.E. |author2=Rees-Milton, K. |author3=Smith, P. |author4=Carran, J. |author5=Pezeshki, P. |author6=Woods, C. |author7=Greer, P. |author8=Anastassiades, T.P. |display-authors = 4 |title=N-acylation of glucosamine modulates chondrocyte growth, proteoglycan synthesis, and gene expression |journal=J. Rheumatol. |volume=32 |issue=9 |pages=1775–86 |year=2005 |pmid=16142878 }}&lt;/ref&gt;

Another nutrient that can help improve the structural support of the body is [[vitamin C]]. Vitamin C contributes to the building blocks of [[collagen]] that can help to strengthen the joints.{{cn|date=August 2024}}

===Surgical interventions===
Surgical procedures attempt to modify, repair, or replace the hip joint in order to allow pain-free usage.{{cn|date=August 2024}}

*''[[Femoral head ostectomy]] (FHO)'' is when the head of the femur is removed but not replaced. Instead, the resulting scar tissue from the operation takes the place of the hip joint. This false joint is less stable with a reduced range of motion than a normal joint, causing an abnormal gait. Nevertheless, pain relief with adequate function can be achieved. The procedure can be performed in all dogs of all sizes, but there are usually better long-term success rates in smaller dogs less than 20&amp;nbsp;kg (44&amp;nbsp;lbs). This procedure is used when there is significant osteoarthritis and a total hip replacement is cost-prohibitive.&lt;ref name=&quot;:5&quot; /&gt;
*''Triple pelvic [[osteotomy]] (TPO)'' involves bone cuts in the pelvis so that the socket portion of the joint can be rotated over the ball; the bones are then stabilized with a bone plate. This procedure is indicated for dogs under 10 months of age. A TPO can be performed to reestablish joint stability and encourage normal joint development. This procedure is not indicated if osteoarthritis is already present. Recovery time is about six weeks.{{cn|date=August 2024}}
*[[Hip replacement (animal)|''Hip replacement'']] has the highest rate of success, especially in severe cases, since it completely replaces the faulty joint. It usually restores complete mobility if no other joint is affected, and also completely prevents recurrence. It is ideal for dogs over 10 months old that already have established osteoarthritis and can no longer be medically managed.&lt;ref name=&quot;:5&quot; /&gt; Hip replacement is also the preferred clinical option for serious dysplasia in animals that weigh {{convert|40|-|60|lb|kg|abbr=on}}.{{cn|date=August 2024}}
*''Juvenile pubic symphysiodesis (JPS)'' is a procedure for very young dogs that manipulates the way the pelvis grows to create a tighter hip. It involves [[cauterization|cauterizing]] the growth plates of the pelvis to halt vertical growth. To compensate, the rest of the pelvis grows outward, in a manner which enhances the &quot;socket&quot; of the hip and provides better support than the dog would have had naturally. Since it relies on growth in puppyhood, it has a very tight window for surgery &amp;ndash; between 4 and 5 months old. This is compatible with hip scoring of puppies at 4 months.{{cn|date=August 2024}}
*''Capsular [[neurectomy]]'' is a procedure in which the hip joint capsule is de-nerved to reduce pain in the hip. This allows the dog to exercise moderately with less pain, thus preventing the leg muscles from weakening from disuse and providing less support to the bad joint. Both hips can be done in one surgery. This surgery should not prevent a future hip replacement if a more complete fix is desired.{{cn|date=August 2024}}

==See also==
* [[Dislocation of hip in animals]]

==References==
{{Reflist}}

==External links==
{{Commons category|Hip dysplasia in dogs}}

{{Authority control}}

[[Category:Dog musculoskeletal disorders]]