The influence of obligatory screening for patellar luxation in Chihuahua and the incidence trend of 10 other commonly canine breeds.

Abstract

One of the most common orthopedic conditions in small animal practice is the luxation of the patella. There are various predisposed breeds for patellar luxation (PL) including Kooiker, Flatcoated Retriever, Jack Russell Terrier and Chihuahua dogs but other breeds can be affected as well. Due to the genetic inheritance of the disease it is possible to reduce the incidence by breed guidelines. The purpose of this research is to show how important it is to test for PL before breeding. The outcome of this study could be used in breeding programs and etiology studies. By using the historic Meutstege database and compare these results with the results of the last five years (till 2015) it is possible to evaluate the change in the trend of the appearance of this disease. In this study eleven different breeds are examined; Chihuahua, Flatcoated Retriever, Kooiker, Labradoodle, Markiesje, Jack Russell Terrier, Fox Terrier, Great Pyrenean, Shiba, Papillon and Havanese. The incidence of PL (grade 1,2,3 and 4) is decreased in general, all breeds taken together, compared with the first PL examinations available in the historic database. The incidence of grade 1 was increased in Chihuahua with 4.7%, Papillon with 4.1%, Havanese with 2.7% and the Markiesje with 11% and grade 2 is grown in Markiesje with 6.9%, Shiba with 3.1% and Labradoodle with 8.7%. The average increase of the incidence of grade 1 PL of the Chihuahua, Papillon, Havanese and Markiesje is 5.63% and the total population average of grade 1 PL of all breeds is 16.0%. The percentage of the first results (Meutstege database) is 21.8%. For grade 2 the total population average of grade 2 PL of all breeds is 4.0%. The percentage of the first results (Meutstege database) is 3.1%. Concluding that the incidence of PL grade 1 in these breeds is reduced over the years, although 16.0% of the population of these breeds is still affected with PL grade 1. PL grade 2 shows a slight increase in the incidence over the years. The incidence of grade 1 in the Chihuahua has grown since 2013 the breeding association obliged breeders to test on this disease, 26.9% to 31.6%. The incidence of PL grade 1 in 2015 is 31.6 % and PL grade 2 is 11.9%. Concluding that PL is a significant problem within the Chihuahua breed, 45% of the cohort is affected and a clear breeding selection program should be advocated for the Chihuahua and other breeds by the breeding association to decrease the incidence of PL.