Effect of repeated arthrocentesis and single joint lavage on cytologic evaluation of synovial fluid in 5 young calves.

The objective of this study was to evaluate the effect of repeated arthrocentesis and a single joint lavage on cytologic variables of synovial fluid. The left tarsi of 5 healthy Holstein calves were selected for the study. Samples of synovial fluid were collected daily for 4 d, then every 4 d until day 24. On day 2, joint lavage was performed with lactated Ringer's solution in all the calves. Cytologic examinations, performed by the same clinical pathologist, included the determination of total protein concentration, total leukocyte count, and differential counts (of neutrophils, lymphocytes, and monocytes). The presence of lameness or swelling and other results of physical examination were recorded regularly during the study. No clinical signs of joint disease were observed during the study. Bacterial cultures of specimens collected on day 2 were negative for all the calves. All cytologic values but 1 peaked on day 2 and progressively returned to normal. In comparison with the results for day 1, the synovial fluid total leukocyte, neutrophil, and monocyte counts were significantly increased on days 2 and 3, and the total leukocyte and monocyte counts were also significantly increased on day 4. The monocyte and lymphocyte percentages were significantly decreased until day 4, whereas the neutrophil percentages were significantly increased until day 8. The total protein concentrations were significantly increased until day 3. There were no significant differences between values for specimens taken 4 d apart. This study demonstrated that, although arthrocentesis induces a moderate inflammatory response, the joints seem to rapidly adapt. A 4-d interval between arthrocenteses is suitable when studying cellular components of the synovial fluid. However, when arthrocentesis is repeated daily, a minimal interval of 8 d should be respected.