The association between
bacterial DNA in stifle joints, including those with cranial cruciate ligament
rupture (CCLR) and medial patellar luxation (MPL), and
osteoarthritis in dogs remains elusive. This study investigated the potential association between the detection of
bacterial DNA and
osteoarthritis in dogs using a broad-range polymerase chain reaction technique targeting the
16S ribosomal RNA gene.
Materials and Methods: Synovial fluid (35 samples) and knee tissue samples (32 samples) were obtained from 35 dogs diagnosed with CCLR (n = 20; 11 males and nine females) or MPL (n = 15; five males and 10 females) who underwent a surgical operation between October 2014 and April 2015.
Results: Dogs with CCLR had a higher average
osteoarthritis score than those with MPL (2.0 ± 0.9 vs. 0.5 ± 0.9; p = 0.005).
Bacterial DNA was detected in the stifle joints of 60.71% of dogs with MPL. Pelomonas spp. (25.00%), Halomonas spp. (17.86%), and 5 other species (17.86%) were the most frequently identified bacteria.
Bacterial DNA was detected in 41.03% of dogs with CCLR. Pelomonas spp. (15.38%), Sphingomonas spp. (10.26%), Halomonas spp. (5.13%), and 4 other species (10.26%) were the most frequently identified bacteria. No significant difference was observed in the prevalence of
bacterial DNA obtained from tissue samples (46.88%) or joint fluid samples (51.43%). The presence of
bacterial DNA was not associated with the type of
knee injury (MPL or CCLR; p = 1.000). There was a higher prevalence of
bacterial DNA in samples from dogs with moderate-to-severe
osteoarthritis (94.44%) than in those with minimal
osteoarthritis (41.18%), and a significant association between the presence of
bacterial DNA and moderate-to-severe
osteoarthritis was identified (p < 0.01).
Conclusion: