de la Vallée de l'Aumance

Canine HD is a developmental trait primarily affecting medium and large sized dogs, and it is also known in Cardigans. However, many Cardi's with affected hips do not seem to suffer a lot and manage to live their lives as any other dog.

 

Canine hip dysplasia is a developmental malformation of the hip joints resulting in secondary joint disease (arthrosis, arthritis) and corresponding clinical symptoms such as pain and lameness. The major cause of CHD is an excessive laxity of the hip joint, characterized by subluxation of the femoral head out of the acetabulum. The aetiology of CHD is not fully understood. Poor quality connective tissue of the joint capsule may play a crucial role. The disease is hereditary, and current data suggest a major gene theory. Heritability may be up to 95 % (!) depending on breed and population studied. Many breed clubs have established a program to control CHD.
Diagnosis of CHD is commonly based on radiographic findings in large-scale screening of dogs. Radiographic technique has been standardized worldwide. The dog is deeply sedated or anesthetized to guarantee adequate muscle relaxation. Then it is positioned in dorsal recumbence with the hind limbs extended caudally and the femora parallel to the spine, to the table top and to each other. The patellae are centered over the femoral shafts.

The severity of CHD is judged based on the degree of subluxation and to a lesser degree on the presence and severity of secondary joint disease. It must be noted though that radiographs do not precisely reflect the genetic make up of a dog itself nor the risk for passing CHD to the offspring. 
Internationally 3 somewhat differing scoring modes are in use:
- the FCI (Fédération Cynologique Internationale)
- the OFA (Orthopedic Foundation for Animals)
- the BVA/KC (British Veterinary Association/The Kennel Club)

 

FCI:

FCI is the umbrella organisation of more than 80 national kennel authorities located in most European countries, in Russia, South America, and Asia. The scientific committe of FCI proposes a 5 grades scoring system from A (reflecting a normal hip joint) to E (indicating severe hip dysplasia). Grades are defined descriptively based on the size of Norberg angle (NA), degree of subluxation, shape and depth of the acetabulum and signs of secondary joint disease. Radiographic evaluation of the hip joints has been implemented as mandatory prerequisite for breeding dogs in many western countries in the last 40 years. Dogs must be at least 1 year of age for official scoring. Hips are usually scored by a single scrutineer per breed club or within a country with some exceptions. Dogs scoring moderate or severe are banned from breeding in most countries. For mildly dysplastic dogs specific breeding restrictions may apply.The following FCI classification is based on radiological features noted on a radiograph taken with the hind limbs extended of dogs between 1 and 2 years of age. It is as objective as possible. It may be adopted for older dogs, but secondary arthrotic changes have then to be judged according to the age of the dog. Final grading is based on the worst hip joint. The mode of publication of the results depends on the bye-laws established by the individual breed clubs.

 

A: No signs of Hip Dysplasia 

The femoral head and the acetabulum are congruent. The craniolateral acetabular rim appears sharp and slightly rounded. The joint space is narrow and even. The Norberg angle is about 105°. In excellent hip joints the craniolateral rim encircles the femoral head somewhat more in caudolateral direction. 
B: Near normal hip joints 
The femoral head and the acetabulum are slightly incongruent and the Norberg angle is about 105° or The femoral head and the acetabulum are congruent and the Norberg angle is less than 105°. 
C: Mild hip dysplasia 
The femoral head and the acetabulum are incongruent, the Norberg angle is about 100° and/or there is slight flattening of the craniolateral acetabular rim. No more than slight signs of osteoarthrosis on the cranial, caudal, or dorsal acetabular edge or on the femoral head and neck may be present. 
D: Moderate hip dysplasia 
There is obvious incongruity between the femoral head and the acetabulum with subluxation. The Norberg angle is more than 90° (only as a reference). Flattening of the craniolateral rim and/or osteoarthrotic signs are present. 
E: Severe Hip Dysplasia 
Marked dysplastic changes of the hip joints, such as luxation or distinct subluxation are present. The Norberg angle is less than 90°. Obvious fl attenting of the cranial acetabular edge, deformation of the femoral head (mushroom shaped, fl attening) or other signs of osteoarthrosis are noted.

 

 

OFA:

The phenotypic evaluation of hips done by the OFA (Orthopedic Foundation for Animals, USA) falls into seven different categories. Those categories are Normal (Excellent, Good, Fair), Borderline, and Dysplastic (Mild, Moderate, Severe).
Once each of the radiologists classifies the hip into one of the 7 phenotypes above, the final hip grade is decided by a consensus of the 3 independent outside evaluations. Examples would be:

1. Two radiologists reported Excellent, one Good - the final grade would be Excellent

2. One radiologist reported Excellent, one Good, one Fair - the final grade would be Good

3. One radiologist reported Fair, two radiologists reported Mild - the final grade would be Mild

The hip grades of Excellent, Good and Fair are within normal limits and are given OFA numbers. This information is accepted by AKC on dogs with permanent identification (tattoo, microchip) and is in the public domain. Radiographs of Borderline, Mild, Moderate and Severely dysplastic hip grades are reviewed by the OFA radiologist and a radiographic report is generated documenting the abnormal radiographic findings. Unless the owner has chosen the open database, dysplastic hip grades are not in the public domain.