Incidence of Canine Elbow Dysplasia in South Africa

(Extracts of article by Prof. R. M Kirberger Dr. N Stander paper published in the Journal of the South African Veterinary Association, 2007)
Elbow dysplasia (ED) is the abnormal development of the elbow joint. It is an all-encompassing term that covers a range of conditions including fragmented medial coronoid process (FMCP), osteochondrosis (OC) and osteochondritis dissecans (OCD); these conditions may occur on their own or in combination with each other.
Elbow dysplasia is inherited as multi-factorial polygenic traits. Within the Rottweiler breed the existence of a major gene has recently been suggested. Heritability varies from 0.10–0.77 and males may have a higher heritability than females.  While a hereditary linkage has been demonstrated, environmental factors also play a role in the development of ED and the subsequent arthrosis.  These factors include overfeeding (i.e. high bodymass), high fat intake, excessive calcium and short bursts of exercise up to the age of 24 months.
Although diagnosis of this condition was recognised back in the 1970s in the USA, it was only in 1998 that radiological testing was introduced in South Africa.  The Kennel Union of South Africa (KUSA) and South African radiologists have adopted the guidelines established by the IEWG for an elbow dysplasia grading scheme to help combat the effects of this often crippling condition on South African dogs.  Regrettably Labradors are amongst the breeds that commonly suffer from this condition. 
These guidelines are as follows:

  • Dogs to be a minimum of 12 months old and should preferably be done at this age.
  • Radiographs to be made simultaneously with the hip dysplasia certification radiographs to save on costs.
  • Radiographs only to be interpreted by qualified veterinary radiologists
  • Only a single maximally flexed good quality ML radiograph of each elbow to be made. It was decided to evaluate only a single view in order to limit costs and thus encourage greater participation in the scheme by dog breeders.

Osteophyte (bone spur) formation at very specific locations within the elbow joints are evaluated for size and graded as follows
Grade 1 (mild arthrosis):               osteophytes <2 mm in size.
Grade 2 (moderate arthrosis):      osteophytes 2–5 mm in size.
Grade 3 (severe arthrosis):           osteophytes >5 mm in size.
In South Africa, results for 340 dogs tested indicated a 20.6% prevalence of elbow dysplasia

The benefit of breeding ED-free dogs is illustrated by the following mating probability results for 13,151 breeding pairs of dogs (primarily Labrador retrievers, Golden retrievers, Rottweilers and German shepherd dogs) with known elbow status of the Orthopaedic Foundation of America

  • Normal elbows × Normal elbows =12.2 % offspring affected with ED.
  • Normal elbows × Dysplastic elbows = 26.1 – 31.3 % offspring affected with ED.
  • Dysplastic elbows × Dysplastic elbows = 41.5 % offspring affected with ED

 

Statistics in South Africa are only now emerging as the awareness of the condition increases and more breeders are screening dogs.  As of 2007, the Labrador ranked No. 12 of larger breeds in terms of incidence of elbow dysplasia screened through the Ondeerstepoort system.  The total number of dogs tested was 340, the second highest of all breeds in the country.  The results are tabled below:

Incidence of Elbow Dysplasia of Labradors in South Africa as of 2007 compared to the Orthopaedic Foundation of America


Breed

Breed Rank

n

% Dysplasia

Grade 1

Grade 2

Grade 3

 

SA

USA

SA

USA

SA

USA

SA

USA

SA

USA

SA

USA

Labrador

12

24

340

33094

20.6

11.5

10.3

8.5

5.6

2.1

4.5

1.0

Within the South African context, the dysplasia prevalence of grade 1 or greater of 20.6% is a cause for concern although these statistics include many dogs x-rayed at over 2 years of age when environmental factors may have had greater influence.  However the LRKC actively strives to improve awareness amongst breeders that will hopefully result in more screening of breeding stock and lead to a significant decrease in the incidence of this potentially crippling condition.