Elbow dysplasia (ED) is a potentially crippling disease of dogs leading to the development of irreversible and progressive arthritis in the elbow joint. Even with early surgical intervention many dogs have chronic pain and lameness. For many veterinarians and breeders, elbow dysplasia is disease that is not only difficult to diagnose, but controversial when it comes to deciding on a dog’s suitability for breeding.
The single biggest misunderstanding when it comes to ED is that to be affected a dog must have clinical signs of lameness. Lame dogs are in fact the “tip of the iceberg” with the majority of dogs being asymptomatic carriers, which has caused the disease to spread to very high levels within certain breeds.
The Rottweiler is currently ranked #2 in breeds affected by elbow dysplasia with only 58.5% of dogs receiving a normal score from the Orthopedic Foundation For Animals (OFA). This number may even be lower considering that not all breeding dogs are x-rayed and not all OFA scores are released for statistical use.
1) What is elbow dysplasia?
Picture credit: http://www.vetsurgerycentral.com/elbow_dysplasia.htm
Elbow dysplasia (ED) is a broad term used to describe Ununited Anconeal Process (UAP), Fragmented Coronoid Process (FCP) and Osteochondrosis of the humeral condyle (OCD). Most Rottweilers with ED have FCP. All three of these conditions are believed to be due to a failure of endochondral ossification, which is the conversion of cartilage to bone during skeletal maturation. The end result is a weakness in the affected area leading to a flap of cartilage (OCD) or fractures of pieces of bone, which are essential to the stability of the elbow joint (UAP, FCP). The piece of bone floating in the joint is like a pebble in a shoe, causing inflammation and pain.
The consequence of ED is the formation of Degenerative Joint Disease (DJD). DJD (arthritis /osteoarthritis) forms in a joint when there is instability in a joint or as a degenerative process with old age. As the cartilage becomes worn the underlying bone is exposed and because the cartilage cannot repair itself osteophytes (spurs) of bone form. Over time if the instability persists more bone is added leading to more arthritis.
Dogs with elbow dysplasia may have severe forelimb lameness or never show any clinical signs. There may be swelling (effusion) in the elbow joint, pain when the elbow is extended and the paw is often held with the foot rotated outwards. In a 1996 study of 55 Rottweilers followed from 3-12 months only 5% of dogs showed signs of lameness but 57% developed radiographic signs of ED by 12 months of age.
2) Diagnosis:
FCP in particular can be very hard to diagnose. Unless a large fragment is visible, it is typically diagnosed by the appearance of secondary DJD, which can take weeks to months to develop. FCP can be seen as early as 7-8 months but may not be diagnosed until the films are sent for OFA evaluation. Sending the films to a Board Certified Radiologist or Surgeon can be helpful to obtain the diagnosis. 3 views of the elbow are recommended to diagnose ED (neutral lateral, hyperflexed lateral, and ventrodorsal). Hyperflexion is used for OFA evaluation because it gives the best view of the anconeal process. 50% of dogs have both joints affected so it is recommended to always x-ray both elbows. In a growing Rottweiler, ED should be one of the top diagnoses to rule out if there is lameness involving one or both front legs that does not resolve with rest.
3) OFA:
The Orthopedic Foundation For Animals scores elbows as normal or dysplastic (DJD I, II, III). Preliminary x-rays can be done at 12 months or 24 months for breeding dogs. A score of DJD I, II or III is based on the millimeters of arthritis found at the anconeal process. Sclerosis (increased bone density) in the area of the coronoid process is also used. Arthritis will not form in young dog with a normal elbow joint therefore an elbow that fails OFA has underlying ED.
4) What is the cause of elbow dysplasia?
Textbooks can be written on this subject and there is no one single cause. Like hip dysplasia ED is multifactorial. Genetics are thought to be of primary importance in high incidence breeds such as the Chow, Rottweiler, German Shepherd (GSD), Bernese Mountain Dog and Retrievers. Conformation, body condition and trauma are other risk factors. Large puppies of high incidence breeds should be kept in lean body condition and not excessively exercised to lessen the risk. Studies are being done on hereditary pattern and found to vary between breeds and sex.
5) Genetics and Breeding
The International Elbow Working Group (IEWG) was established in 1989 by a group of veterinary radiologists, clinicians and geneticists for the diagnosis, control and screening of elbow dysplasia. Their goal is an open database and to provide guidelines for breed registries on ED.
According to the IEWG the percentage of affected puppies will vary depending of the severity of DJD in the parents. The following numbers are from a study on the incidence of ED in Rottweilers:
Parent 1 OFA Score Parent 2 OFA Score Offspring Affected* Normal Normal 31% Normal Mild ED (DJD I) 43% Normal Moderate/Severe ED (DJD II/III) 48% ED (DJD I/II/III) ED (DJD I/II/III) 56%
*offspring affected meaning % of puppies with ED
FCP has become a major threat for Berners, Retrievers, Rotties and the GSD because it has spread within the population to a high level through the breeding of carriers that have no clinical signs and are therefore assumed to be unaffected. This is supported by the percentage of affected puppies in the table above from two seemingly normal parents.
IEWG recommendations for reducing the incidence of elbow dysplasia:
- have large numbers of animals participating in screening programs
- high quality films evaluated by experts
- open database for easy accessibility
- ideally only normal dogs used for breeding
- dogs with scores of DJDII or III should not be used for breeding
Until a DNA test is available to confirm genetically predisposed dogs the only way to accurately predict the incidence of ED is by evaluating not only the parents but also entire litters. Relying on simply the absence symptoms to determine breedability is inaccurate and will lead to a further increase in ED in the breed. Many breeders have now started requiring OFA hip and elbow radiographs from all puppy buyers to better estimate the dogs affected in their program. The decision to use a DJD I dog should include evaluation of not just the parents’ OFA scores, but more importantly the scores of all littermates. For example: not breeding a DJD I dog whose parents are OFA Normal but 75% of it’s littermates are DJD II, versus breeding a DJD I dog whose parents are OFA Normal, and all its littermates are also OFA Normal. By working together breeders and veterinarians will be able to reduce the incidence of elbow dysplasia in the population by using the same scrutiny that was done in the past with hip dysplasia.
Dr Wendy James is a Rottie enthusiast who was owned by 13 year old Dakota until she passed over the rainbow bridge in November. She currently practices Veterinary Medicine in Calgary and has special interests in dermatology and reproduction.
Dr Wendy James, BSc, DVM
References:
- JAVMA 1996 Oct 15;209(8):1427-30 Relationship Between Physical Signs of Elbow Dysplasia and Radiographic Score in growing Rottweilers.
- WSAVA 2002 Congress Dr Pim Wolvekamp, DVM, PhD, Dipl ECVDI The Many Faces of Elbow Dysplasia.
- Tufts Canine and Feline Breeding and Genetics Conference, 2005; Examining Elbow Dysplasia
- Genetic Control of Hereditary Skeletal Diseases; WSAVA 2002 Congress; Dr H.A.W. Hazewinkel DVM, PhD, Dipl ECCS, Dipl ECVCN.
- Orthopedic Foundation for Animals: http://www.offa.org/elbowinfo.html
- International Elbow Working Group: http://www.iewg-vet.org/about.htm
- Elbow Dysplasia in Dogs Dr Daniel A Degner, Dipl ACVS http://www.vetsurgerycentral.com/elbow_dysplasia.htm
- Dynamic Ulna Osteotomies in Canine Elbow Dysplasia; WSAVA 2002 Congress; Dr Aldo Vezzoni Dipl ECVS
- Projections of the Canine Elbow; WVC 2004; Dr Craig Long
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