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Dextrose solution is often used to treat purulent vaginal discharge and endometritis, more so in organic than in conventional systems. The question is how effective is the treatment and what are the implications on reproductive parameters. Two studies investigated, one by Dr M. G. Maquivar and colleagues, entitled:Effect of intrauterine dextrose on reproductive performance of lactating dairy cows diagnosed with purulent vaginal discharge under certified organic management, and the other by Dr V.S. Machado and co-workers, with the title: The effect of intrauterine infusion of dextrose on clinical endometritis cure rate and reproductive performance of dairy cows. Both studies were reported in the Journal of Dairy Science, Volume 98 of 2015, respectively at pages: 3876 to 3886, and 3849 to 3858.
The objective of the Maquivar study was to assess the response to treatment in terms of clinical cure and resumption of oestrus of cows with purulent vaginal discharge (PVD) that received either a 50% dextrose (DEX) solution infused into the uterus or no infusion, as control (CON). The subsequent pregnancy per artificial insemination (AI) with and without PVD was also recorded.
A total of 2852 cows from two dairy herds were screened for PVD using the gloved hand technique at about 26 days in milk. Cows with vaginal discharge scores of 2 or 3 (scale 0 to 3) were divided by lactation number and randomly allocated to two treatment groups, one group receiving an infusion of 200 mL of a 50% DEX solution into the uterus and the other group received no infusion – the control (CON). Fourteen days after therapy, cows with PVD were re-examined, that is at about 40 days in milk to assess the response to the infusion. All cows were subjected to the same reproductive program, which consisted of oestrus detection twice daily for the first five AI’s; then, the open lactating cows were turned out with bulls. Cows displaying signs of standing oestrus underwent AI and no reproductive hormones were used. Pregnancy diagnosis was performed via rectal palpation at about 40 days after AI.
The risk of culling within 14 days after therapy was not different between the two groups. Cows with PVD had a greater cervical diameter and decreased pregnancy compared with cows without PVD. Treatment with DEX solution increased the proportion of cows with clear vaginal discharge (clinical cure) and cyclicity (resumption of oestrus) 14 days after therapy compared with CON cows. Pregnancy per AI for DEX cows was significantly greater than that for CON cows. Cows without PVD had a greater proportion that cycled and being pregnant and they showed less pregnancy losses compared with DEX or CON cows. With respect to the objective of the study, the results suggest that infusion with DEX solution into the uterus without other medication may improve the reproductive performance of cows with PVD.
The main objective in the Machado study was rather similar, that is to evaluate the administration of a dextrose solution into the uterus as a treatment against clinical endometritis (CE). The authors evaluated the CE cure rate and the subsequent reproductive performance. The association of several relevant risk factors, such as retained placenta (RP), metritis, CE, poor ovulation and body condition score with reproductive performance and early embryonic mortality were also evaluated.
A total of 1313 Holstein cows housed on four commercial dairy farms were used in the study. At about 7 days in milk the cows were examined for metritis. To determine if cows had ovulated at least once before about 44 days in milk, the presence of a corpus luteum was observed at about 30 and again at 44 days in milk. Also, at about 30 days in milk, CE was diagnosed; cows with purulent or mucus-purulent vaginal discharge were diagnosed as having CE. The cows thus diagnosed were randomly allocated into two treatment groups: the one group being infused in the uterus with 200 mL of a 50% dextrose solution, whereas the other group was not infused (Control). Clinical endometritis cows were re-evaluated as described above at about 44 days in milk and those free of purulent or mucus-purulent vaginal discharge were considered cured.
The results showed that infusion with dextrose tended to have a detrimental effect on the CE cure rate, but infusion did not have an effect on first-service conception rate and early embryonic mortality. A hazard model showed that several variables affected reproductive performance; these were RP, CE, lactation number and poor ovulation. The model indicated that cows that did not have RP or CE were more likely to conceive than cows that were diagnosed with RP or CE. Cows that had RP were at 3.36 times higher odds of losing their pregnancy than cows that did not have RP. In addition, cows diagnosed with CE were at 2.16 higher odds of losing their pregnancy than cows without CE. In terms of the objective of the study, infusion of 200 mL of a 50% dextrose solution into the uterus as a treatment for CE had a strong statistical tendency to decrease CE cure rate, it did not improve first-service conception rate and early embryonic mortality and it did not decrease calving-to-conception interval.
General observation: The two studies did not concur as to the efficacy of a dextrose solution to treat PVD and endometritis, even though both used the same concentration and amount. There could have been other not discussed reasons and variables responsible for the discrepancy. Thus, it is clear that the subject warrants further investigations.