B. Zorko(1), T. Ivanusa,(1) R. Pelc(1)(2) EJCAP 2008 17 2 145-148 The aim of the study was to evaluate the effects of the progression of CHD and degenerative joint disease on the working capability of a population of police working dogs. In the first part of the study, the whole health documentation of all dogs was reviewed and gathered all necessary radiographs of hip joints that were taken at first presentation. In the second part, clinical examination and radiographs of all dogs were taken 60 months after first examination and the progression of hip dysplasia was evaluated by the FCI scheme. All dogs were male, 35 German shepherds and 5 Rottweilers. The Norberg-Olsson angle in the first set of radiographs was 105.54 ± 3.22° in 37 dogs without signs of hip dysplasia and 100.17 ± 2.99° in 3 dogs with initial mild dysplasia. In the second set of radiographs, taken after 60 months of service, the Norberg-Olsson angle was 105.60 ± 3.67° in 23 dogs with no signs of hip dysplasia and 101.62 ± 4.49° in 17 dogs with hip dysplasia. On the first set of radiographs, secondary degenerative changes were found in 3 dogs with initial mild dysplasia (7.5%) and in 14 dogs (35%) on second radiographs. The position of the centre of the femoral head on first radiographs was outside the dorsal acetabular rim in 25 (31.25%) hip joints; at the level of the rim in 30 (37.5%) and inside in 25 (31.25%). On follow-up radiographs it was outside in 41 (51.25%); at the level of the rim in 26 (32.5%); and inside in 13 (31.25%) hip joints. The mean femoral angle of inclination for all 40 dogs was 132.50 ± 4.39°. If it occured, the increase in degree of hip dysplasia was generally more than one degree. In 57.5% of cases hip dysplasia was not determined on follow-up radiographs. All dogs with some degree of hip dysplasia were German shepherds, but only one of them had clinical symptoms connected to CHD. The progression of hip dysplasia did not correlate with work period of the dogs, and has no influence on working ability of these dogs, despite their active duties. No dog in this study was lost due to CHD. Key words: veterinary medicine; working dogs; hip dysplasia