Assessment of Inflammatory Cytokine Concentrations During Diagnosis and After Treatment of Postpartum Dairy Cows with Clinical and Subclinical Endometritis
The objectives of the present study were (1) to compare serum inflammatory cytokine [Tumor necrosis factor-alpha (TNF-α), Interleukin-1beta (IL-1β), Interleukin-6 (IL-6), Interleukin-8 (IL-8), and Interleukin-10 (IL-10)] levels between healthy dairy cows, cows with clinical endometritis (CE) and subclinical endometritis (SCE) during early postpartum (pp), (2) to observe the treatment and time-related alterations of these cytokines. A total of 127 Holstein-Friesian dairy cows were evaluated in the study, and three consecutive examinations and blood samplings were performed at 21-27 (E1), 28-34 (E2), and 35-41 (E3) days in milk (DIM). Reproductive controls were performed only at E1 and E3. Cows were classified as endometritis negative, CE, and SCE according to their vaginal discharge score (VDS) and percentage of endometrial polymorphonuclear cells (PMNs) at E1. Following diagnosis, a single dose of intrauterine 500 mg cephapirin benzathine was administered to CE and SCE cows. The VDS and PMNs of the cows were re-evaluated at E3, and CE and SCE cows were divided into two sub-categories as cured and uncured. Also, endometritis negative cows were divided into two sub-categories as healthy cows and new endometritis cases. The new endometritis cases were not evaluated in the study. Finally, five subgroups to observe the treatment and time-related alterations, and three groups to evaluate the diagnostic potential of the cytokines were established. All cytokine levels were measured by ELISA. Diagnostically, TNF-α (P < 0.05), IL-1β (P < 0.001) and IL-8 (P < 0.05) levels were significantly higher in cows with CE than in healthy cows. Nevertheless, IL-6 and IL-10 levels were similar between healthy, CE, and SCE cows (P > 0.05). Similarly, no differences were observed in all cytokine levels between healthy and SCE cows (P > 0.05). In repeated measurements concerning subgroups, no apparent relationship was observed between inflammatory cytokine levels and treatment response. Also, all cytokine levels showed linear course regardless of treatment response and uterine health condition within subgroups between 21-41 DIM (P > 0.05). As a result, high early pp serum IL-1β, TNF-α, and IL-8 levels may reflect a persistent clinical uterine infection. However, no inflammatory changes have emerged to the extent that could affect the systemic inflammatory cytokine levels of SCE cows.