Summary
Objective: To measure the concentrations of nerve growth factor (NGF) in the synovial fluid
from normal dogs and dogs with osteoarthritis (OA) secondary to common joint disorders.
Methods: Nerve growth factor synovial concentrations were measured by ELISA assay in 50 dogs
divided into three groups: 12 healthy, 16 affected by acute lameness within seven
days before enrolment, and 22 with chronic lameness persisting by more than one month
before enrolment and accompanied by radiological signs of OA. Both acute and chronic
lameness were secondary to orthopaedic diseases involving the shoulder, elbow and
stifle joints. Nerve growth factor synovial concentrations were compared between means
for healthy and acute groups and between the three groups using an F-test. Significance
level was set at p ±0.05.
Results: Nerve growth factor was detected in all canine synovial fluid samples. However, the
mean synovial NGF concentration of healthy dogs (3.65 ± 2.18 pg/ml) was not significantly
different from the mean value in dogs with acute lameness (6.45 ± 2.45 pg/ml) (p ±
0.79). Conversely, the mean synovial NGF concentration in dogs with chronic lameness
(20.19 ± 17.51 pg/ml) was found to be significantly higher than that found in healthy
dogs (p ±0.01).
Clinical significance: This study demonstrates for the first time the presence of NGF in canine synovial
fluid and its increased concentrations in dogs with chronic lameness compared to healthy
dogs and dogs with acute lameness. The association between chronic lameness and raised
synovial concentrations may suggest an involvement of NGF in OA inflammation and chronic
pain.
Keywords
Nerve growth factor - synovial fluid - canine osteoarthritis - lameness - pain