Patellar luxation in four dog breeds in the Netherlands

Abstract

This study evaluated the incidence and gradation of patellar luxation in four dog breeds in the Netherlands, presented for patellar luxation (PL) examination to one of the ‘Meutstege’ group certified orthopaedic surgeons between 1994 and 2011. PL was graded according to Putman’s grading system by a limited group of experts. The results were filed. Different trends in PL were analysed. The incidence for PL in Flat-Coated Retrievers was 6% in 2011. The Dutch Kooiker dog has an incidence of 14% for PL, the Jack Russel Terrier 8% and the Chihuahua 48%. There was a significant downward trend for FCR, KK and JR during the examination period, but not for CHI. In all four breeds most affected animals had grade 1 PL. In the FCR and JR grade 2 and 3 were seen occasionally, but there was no significant decrease in the amount of animals with grade 2 or 3 in time. A decrease was seen though in the KK. The Chihuahua had the most diffuse distribution, with high percentages of animals with patellar luxation grade 1 and 2. The sex ratio (males:females) was 1:1.73 for the FCR, 1:1.25 for the KK, 1:2.53 for the JR and 1:1.15 for the CHI. The percentage of ‘loose’ patella in the animals that were graded ‘free’ of PL was 26% in the FCR, 20% in the KK, 27% in the JR and 37% in the CHI. FCR was the only breed were LPL was more common than MPL. The ratio MPL: LPL in this breed was 1:1.69. In the other breeds MPL was more common, the ratios for KK, JR and CHI were respectively 1:0.72, 1:0.86 and 1:0.03.