Flat coated retriever.
Encyclopaedia Britannica, 11th Edition
The Orthopedic Foundation for Animals reports 1.5% of screened flat-coated retrievers are affected with luxating patellas. With this number in mind I was surprised at the high incidence of patellar luxation (PL) in Dutch flat-coated retrievers but also encouraged with the progress made in such a short time – a reduction to 18% from 28% in 17 years.
The success in reducing PL points to the progress that can be made with diligent screening programs but the plateau also highlights the limitations of these programs. As the authors suggests the inclusion of breeding values in improving future performance. Other studies have already shown the effectiveness of EBV and I suspect we will see greater integration of EBVs to breeding programs.
I guess this also means a future post on breeding values.
For those who don’t feel like following the reference link, here is the abstract:
Canine patellar luxation has been described in various dog breeds, with high prevalence especially in smaller dogs. Most dogs suffer from medial displacement of the patella, although in larger dogs lateral displacement is also seen. A sex predisposition has been described for females. Patellar luxation is considered a polygenic, multifactorial disorder. From 1990 to 2007, in total 3834 Flat-Coated Retrievers were screened; 23.6% of those animals were affected with patellar luxation. Lateral displacement of the patella was most common in this breed (61% of cases), whereas medial (31% of cases) and lateral and medial (8% of cases) were less common. Unilateral involvement (51% of cases) was just as often observed as was bilateral involvement (49% of cases). Females were more often affected with patellar luxation (30% of all tested females) than were males (17% of all tested males). The heritability of patellar luxation was 0.17 ± 0.03 in this population, and breeding with one affected parent increased the prevalence of patellar luxation in offspring by 45% compared to that with two unaffected parents. Since the start of the screening program, there was an initial decrease from 28% to 18% in incidence, but this stagnated thereafter. The annual average estimated breeding values followed the same pattern. With approximately one quarter of the Dutch Flat-Coated Retrievers being affected with patellar luxation, this population shows unusually high prevalence compared with reports in other large-breed dogs. The heritability for patellar luxation in this population was moderate (0.17), indicating that environmental factors play a large role in the manifestation of the disorder. A screening program reduced the prevalence of patellar luxation in this breed, but improvement has recently stagnated. Inclusion of breeding values in the screening program could improve its effectiveness
REFERENCE
Lavrijsen IC, Heuven HC, Breur GJ, Leegwater PA, Meutstege FJ, & Hazewinkel HA (2013). Phenotypic and genetic trends of patellar luxation in Dutch Flat-Coated Retrievers. Animal genetics, 44 (6), 736-41 PMID: 24033452
Science and Dogs 
Very interesting stuff. My Flat Coat was Dutch and developed a patella luxation at the age of 1 1/2. It went away with the strengthening of the leg muscles and by giving two steroid injections. The combination made the muscles stronger and more compact thus shortening the lenght of muscle and tendins and finally keeping the patella in place. The problem disappeared in a couple of months and we avoided an operation!
(www.dr-dog.eu)