Quantification of the uterine involution and dimensions, hormonal response and reproductive performance of pyometric and healthy dairy cows treated with Dinoprost

The aim of the present study was to investigate the effects of a PGF2α analogue (Dinoprost) on involution of the puerperal uterus, especially with pyometra during 35 to 45 days postpartum in multiparous high yielding Holstein dairy cows. At days 40 ± 5 postpartum, 1250 cows were ultrasonographically examined. Fifty cows were diagnosed as pyometric. Fifty pyometric and 50 clinically healthy cows were assigned randomly to one of four groups. Groups were: 1.) Pyometric+Dinoprost cows (PD, n = 25 treated with 25 mg of Dinoprost), 2.) Pyometric+Saline cows (PS, n = 25 treated with saline), 3.) Healthy+Dinoprost cows (HD, n = 25 treated with 25 mg of Dinoprost), and 4.) Healthy+Saline cows (HS, n = 25 treated with saline). All treatments were given intramuscularly. Ultrasonography was performed at the time of examination and 7 days later to evaluate changes in uterine diameter. Treatment with Dinoprost significantly reduced gross uterine diameter in PD in comparison to the PS group in the presence or absence (P4 concentrations <1 ng/ml) of an active corpus luteum. Dinoprost treatment did not decrease gross uterine diameter in groups HD and HS. Luminal diameter was significantly smaller in the PD than in the PS group. Pregnancy rate of PD was greater than PS cows (36% vs 20%, respectively). Days to first service (110 d vs. 140 d) and open days (160 d vs. 190 d) were shorter in PD cows than PS cows. It was concluded that injection of 25 mg of Dinoprost to pyometric cows had uterotonic effects in presence or absence of functional corpus luteum. Therefore, this treatment can help uterine involution in puerperal dairy cows affected by pyometra and consequently improved reproductive performance. ______________________________________________________________________________________


Introduction
The general goals for post-partum reproductive health in dairy cattle is for the uterus to be completely involuted and free of infection, and for cows to be cyclic by the time they enter the breeding period after 50 to 60 days in milk (DIM) (LeBlanc et al., 2002).After parturition, bacteria from the animal's environment contaminate the uterine lumen of most cattle.Infection persists in the uterus of many animals for more than three weeks, with about 15% of dairy cattle having signs of clinical endometritis (Sheldon, 2007).Endometritis is an inflammation of the endometrial lining of the uterus without systemic signs, occurring at least 21 days after calving (Barlund et al., 2008), which is often associated with chronic post-partum infection of the uterus with pathogenic bacteria, primarily Arcanobacterium pyogenes, Fusobacterium necrophorum, Trueperella pyogenes, Escherichia coli and Bacteroides Spp (Bondurant, 1999;Karstrup et al., 2017).Untreated endometritis progresses to pyometra which is characterized by accumulation of purulent or mucopurulent material within the uterine lumen and distension of the uterus in the presence of a persistent corpus luteum and a closed cervix 43 days or more after calving (Sheldon et al., 2006).Pyometra can be considered a subset of endometritis in which cows ovulate in the presence of a contaminated uterus (Galvão et al., 2011).When cows with chronic endometritis ovulate, pyometra often develops within a few days.During the progesterone-dominated phase the uterus has a reduced resistance to infection (LeBlanc et al., 2002).It has been noted that during endometritis it is the presence of corpus luteum, with its secretion of progesterone, which results in pyometra (Kennedy & Miller, 1993).Retention of the corpus luteum is believed to be due to a failure in the pulsatile release of uterine PGF 2α (Prostaglandin F2 alpha) which is controlled by an interaction of luteal oxytocin and ovarian steroids (Vighio et al., 1991).Formation of the first corpus luteum after parturition and secretion of progesterone often precede the onset of uterine disease (Lewis, 2004;Abere & Belete, 2016).However, many spontaneous uterine infections are established within 3 weeks after parturition, before ovulation of the first dominant follicle (Sheldon et al., 2002).
The incidence rate of pyometra varies between herds, but on individual farms as many as 8% of calvings may be followed by pyometra (Etherington et al., 1985).Lech et al. (1998) reported that pyometra incidence rates may range from 20 to 60 cases per 1,000 cows in all post-partum dairy cows.Inadequately standardized cost data makes it difficult to determine true estimates, but based on studies done in Ohio and Georgia by Bellows et al. (2002), it is estimated that metritis and pyometra cost approximately $4.70 per dairy cow.The adverse effects of puerperal metritis, clinical endometritis, subclinical endometritis, and pyometra on reproductive performance have been described sufficiently (Kim & Kang, 2003;Gilbert et al., 2005;Sheldon & Dobson, 2004).The duration of pyometra is inversely related to subsequent fertility in dairy cattle.Cattle with pyometra lasting longer than two months and those with large amounts of intrauterine pus have lesser chances of subsequent fertility (Roberts, 1971).Complete recovery and conception is more likely in cases that have existed for less than 120 days.Cases of longer duration are reported to produce degenerative uterine changes (Roberts, 1971);hence, increasing the culling rate.Today the treatment of choice is administration of PGF 2α or its analogs at normal luteolytic doses.Exogenous PGF 2α induces luteolysis, reduces progesterone, and enables the uterus to resolve infections.Expulsion of exudate and bacterial clearance of the uterus follows in 90 -100% of treated cases.
The aim of this study was to evaluate the efficacy of Dinoprost injection on involution of the puerperal uterus, especially with pyometra during 35 to 45 days postpartum in multiparous high yielding dairy cows.To the best knowledge of the authors, there are not sufficient studies investigating the effects of PGF 2α on uterine diameter changes in pyometric cows.It is also not clear to what extent does treatment with PGF 2α affect uterine dimensions.We hypothesized that the treatment with Dinoprost in pyometric cows would decrease uterine dimension sizes which are probably independent of luteolysis and are probably due to uterotonic effects of Dinoprost.This reduction may result in improved uterine involution and reproductive performance of pyometric dairy cows.Therefore, our null hypothesis was that treatment with Dinoprost has similar effects on uterine dimensions, hormonal status and reproductive performance of healthy and pyometric cows.

Materials and Methods
A total of 1,250 multiparous cows (parity range 1 to 6 calvings) from eight commercial Holstein dairy farms located in Provinces of Tehran and Karaj, Iran were examined 35 to 45 days postpartum.The herds ranged from 150 -800 milking cows and the rolling herd averages were between 9000 -12,000 kg of milk/cow per year.Lactating dairy cows were housed in corrals and milked three times daily.Transition dairy cows (between 21 d before expected parturition and 21 d post-partum) were housed in pre-and post-partum dry lot pens.Within a herd, cows were fed the same total mixed ration (TMR) formulated to meet or exceed the NRC (National Research Council, 2001) nutrient requirements for lactating Holstein cows weighing 680 kg and producing 45 kg of 3.5% FCM (Fat Corrected Milk).Reproductive management varied among farms, however, all dairy farms relied on estrus detection for most of their breeding and their voluntary waiting periods were set to 40 -60 DIM.The gynaecological examinations were performed weekly beginning on the day 10 ± 3 post-partum.The clinical examination included ultrasonographical and transrectal palpation of the uterus, cervix, and ovaries.
Ultrasonography was conducted using a 7.5-MHz transrectal linear transducer (Agro Scan, France).Uterine characteristics of the pyometric and clinically healthy cows were assessed according to validated methodology (Sheldon et al., 2003;Barlund et al., 2008).All transrectal palpations, uterine measurements, and ultrasonographic exams were performed by the same veterinarian throughout the experiment.Pyometra was defined as accumulation of mixed echo density fluid in the uterine lumen and distension of the uterus with thin walls and without uterine tone in the presence of a corpus luteum.The diameters of the uterine horns were measured using the internal calipers of the ultrasound machine.The larger diameter of the uterine horns was initially identified and two diameters of the enlarged uterine horn were evaluated approximately 10 cm from the bifurcation of the uterus.If intraluminal fluid was detected during the initial ultrasound examination of the uterus an attempt was made to measure the luminal diameter in the area of the greatest fluid accumulation (Barlund et al., 2008).Minimal pressure was applied with the ultrasound transducer to the top of the uterus to avoid deformation of the uterine horns when performing these measurements.The first measurement was from serosa to serosa to obtain the gross diameter of the uterine horn (Sheldon & Dobson, 2000).The second measurement was from submucosa to submucosa to obtain lumen diameter.The difference between the first and the second measurements estimated uterine wall thickness.The third measurement was from submucosa to vascular layer of uterus to obtain the endometrium diameter.Measuring the endometrium diameter of pyometric cows was technically difficult because of the accumulated pus and fluids which increased the inner pressure of uterus making measurements inaccurate.Thus, instead of endometrium diameter, the luminal diameter of pyometric cows were measured and reported.Therefore, variables considered in the current trial were: 1.) uterine diameter changes which were obtained from serosa to serosa measurements.2.) endometrial diameter changes for healthy cows which were obtained from submucosa to vascular layer measurements, 3.) luminal diameter changes specifically for pyometric cows which were obtained from submucosa to submucosa, and 4.) plasma progesterone, estradiol and haptoglobin concentration changes which were measured with commercial kits.
Fifty cows out of 1,250 were diagnosed as pyometric cows 35 -45 days post-partum and served as treatment groups as follows: Cows in group PD (n = 25; Pyometric+Dinoprost) were treated intramuscularly with 25 mg of Dinoprost.Cows in group PS (n = 25; Pyometric+Saline) were treated with 5 ml saline, also by intramuscular injection.Fifty healthy cows with clinically normal uteri also served as control groups as follows: Cows in group HD (n = 25; Healthy+Dinoprost) were treated with 25 mg of Dinoprost.Cows in group HS (n = 25; Healthy+Saline) were treated with 5 ml saline.PGF 2α (Dinoprost tromethamine; 25 mg/dose; Enzaprost) was from Ceva Santé Animale, France.
Concurrent with ultrasonography, blood samples of progesterone, estradiol and haptoglobin determination were collected at the time of treatments and 7 days later from the tail vein or artery into heparinized tubes.The collected blood was immediately centrifuged at 3000 × g for 20 min and plasma was stored at -20 °C until assayed.Plasma progesterone concentration was used as a criterion to classify cows to groups having a functional corpus luteum or lacking a functional corpus luteum at the time of Dinoprost or saline injection.Cows with plasma P4 >1.0 ng/mL were classified as having a functional corpus luteum present, whereas cows with plasma P4 <1.0 ng/mL were classified as lacking a functional corpus luteum as described previously (Rivera et al., 2005;Masoumi et al., 2012) The progesterone and estradiol levels were determined by commercial Elisa kits (DRG Ins.GmbH, Germany) as described previously by Dirandeh et al. (2015a).The intra-and interassay coefficients of variation were 3.7 and 8.3% for P4 and 2.71 and 6.72 for Estradiol.The haptoglobin levels were also determined by commercial Elisa Kit (Bio-X Diagnostics, Belgium).Ultrasonographic findings, plasma progesterone, estradiol and haptoglobin concentrations were analyzed by ANOVA mixed models using SAS software (SAS 9.3;2003; SAS Institute Inc., Cary, NC, USA) for Windows with the following model: Where:µ is the population mean, α i is the treatment effect, τ j is the effect of sampling day or time, ατ ij is the interaction between time and treatment, and e ijk is residual effects.
The data were analyzed separately for pyometric cows having no functional corpus luteum (P4 concentrations <1 ng/ml, Dirandeh et al., 2015b;Masoumi et al., 2017) to determine if uterine diameter changes were solely due to luteolysis or other effects of PGF 2α such as uterotonic effects.Rankit plots and Wilk-Shapiro tests were used to assess the normality of the residuals.Significance was declared at P <0.05.The binomially distributed reproductive data were analyzed using Logistic procedure of SAS.Significance was declared at P< 0.05 unless otherwise indicated.

Results
The results showed that treatment of pyometric multiparous cows with 25 mg Dinoprost (PD cows) at 35 -45 days post partum, significantly (P <0.05) reduced the uterine diameter in comparison to saline treated pyometric cows (PS cows) 7 days after Dinoprost injection (Figure 1).The mean uterine diameter (serosa to serosa) of PD and PS groups at the time of Dinoprost injection and 7 days later were (61 ± 2.28; 35 ± 2.20 mm) and (49 ± 2.35; 52 ± 2.26 mm), respectively.The effect of Dinoprost injection on uterine diameter in clinically healthy cows (HD cows) was not significant in comparison to saline treated clinically healthy cows (HS cows) (P >0.05) (Figure 1).The mean uterine diameter of pyometric cows and healthy cows at the beginning of treatments were 55 ± 1.77 and 38 ± 1.96 mm, respectively.The difference between mean uterine diameter of pyometric and healthy cows at the beginning of treatments was significant (P <0.05).
Open bars = First uterine diameter at the time of treatments.Filled bars = second uterine diameter 7 days after treatments.X axis represents experimental groups.Analysis of data for cows lacking a functional corpus luteum (Progesterone < 1 ng/ml) showed that Dinoprost injection significantly decreased the uterine diameter and luminal diameter (P <0.05) (Figure 2).The mean uterine diameter at the time of treatment and 7 days later in pyometric cows lacking a functional corpus luteum treated with Dinoprost was (50.5 ± 6.14, 31.5 ± 3.06 mm), in pyometric cows lacking a functional corpus luteum treated with saline was (43.00 ± 3.13, 55.00 ± 9.67 mm), in clinically healthy cows lacking a functional corpus luteum treated with Dinoprost was (33.66 ± 1.60, 32.00 ± 1.73 mm) and in clinically healthy cows without a functional CL treated with saline was (30.72 ± 1.16, 30.30± 1.08 mm) respectively.The results showed that treatment of healthy cows lacking a functional corpus luteum with Dinoprost did not decrease uterine diameter in comparison to healthy cows lacking a functional corpus luteum treated with saline (P <0.05) (Figure 2).
Open bars = First progesterone concentration at the time of treatments.Filled bars = second progesterone concentration 7 days after treatments.X axis represents experimental groups.Pregnancy rate of PD was greater (P <0.05) than PS cows (36 % vs 20 % respectively) but it did not differ (P >0.05) in healthy cows (44 % vs. 48 % in HP and HS groups, respectively).Days to first service of PD cows (110 d) was shorter (P <0.05) than PS cows (140 d) and also open days of PD cows (160 d) was shorter (P <0.05) than PS cows (190) (Table 1).
Open bars = First estradiol concentration at the time of treatments.Filled bars = second estradiol concentration 7 days after treatments.X axis represents experimental groups.

Discussion
This study was designed to investigate the effects of Dinoprost, a natural occurring PGF 2α analogue, on uterine diameter changes in pyometric and healthy cows in presence or absence of functional corpus luteum.We hypothesized that Dinoprost would improve the uterine involution process in pyometric cows with its non-luteolytic effects in the absence of a functional corpus luteum.However, Dinoprost has luteolytic effects and would demise a functional corpus luteum and induce estrous to clean the uterus of accumulated pus in cows bearing a functional corpus luteum.When endometritis progresses to pyometra, the uterus accumulates a considerable amount of purulent exudate, which is usually palpable because the cervix is typically constricted enough to prevent the exudate from draining freely causing the uterus to become distended (Arthur et al., 1982).Treatment of pyometra does not seem to be controversial (Gilbert & Schwark 1992).The use of prostaglandins to treat pyometra has been recommended and evaluated (Steffan et al., 1984;Etherington et al., 1985).However, this study did not attempt to assess the therapeutic effect of the PGF 2α treatment on pyometra.The transrectal ultrasonography was used to diagnose pyometric cows and measure uterine diameters.Transrectal ultrasonography is a non-invasive and reliable method to investigate the reproductive tract including uterine dynamics (involution) and has been used to detect intrauterine fluid accumulation associated with endometritis (Dhaliwal et al., 2001;Kasimanickam et al., 2004;2005) and offers the advantage of an immediate diagnosis.Transrectal ultrasonography for uterine cross-sectional images had high coefficients of determination (Okano and Tomizuka, 1987).Fifty out of 1,250 cows (4%) in 8 commercial dairy farms were detected as pyometric cows.This is in agreement with what was reported by Etherington et al. (1985) and Lech et al. (1988) who indicated an incident rate of 8 and 2 to 6 percent in dairy herds.Sheldon et al. (2008) stated that pyometra comprises less than 5 percent of clinical cases of uterine diseases.
The results of this study demonstrated that 25 mg of Dinoprost reduced the uterine diameters of pyometric multiparous cows treated 35 -45 days post-partum in the presence or absence of a functional corpus luteum, but did not have a significant effect on uterine diameters in healthy multiparous cows.Reduction in size is thought to be a response of myometrial contractility (Melendez et al., 2004) following the demise of an functional corpus luteum and induction of estrus in cows having a PGF 2α responsive corpus luteum.The estrus leads to physical expulsion of bacterial contaminants and inflammatory products as well as a possible improvement in the uterine defenses under low progesterone (Kasimanickam et al., 2005).The PGF 2α administration positively influenced uterine involution and induced estrus in cows with luteal tissue (Lindell & Kindahl 1983;Young & Anderson 1986).Nevertheless, the effect of PGF 2α did not depend on presence of a functional corpus luteum at the time of treatment (Galvao et al., 2009).In our study, mean plasma progesterone concentration at the time of treatment and 7 days later was not significantly different between Dinoprost treated and saline treated pyometric cows.Hence, the luteolytic effects of Dinoprost would not justify reductions in uterine diameters.Blood samples for estradiol measurement were taken every week on herd visits.However, it seems that timing of blood sampling for estradiol assays was not performed at the appropriate time after treatment with Dinoprost.Estradiol measurements one week after Dinoprost injection may not have a good value of interpretation because estrus usually occurs in 3 -4 days following PGF 2α treatment (Gustafsson et al., 1976;Masoumi et al., 2017).Acute phase proteins are typical pathological responses to tissue damage or inflammation produced by infections, trauma, neoplasia, or other causes.Haptoglobin is one of the acute-phase proteins which has been considered as the most reactive proteins in cattle (Melendez et al., 2004).Any inflammatory process such as infection, extreme stress, systemic infections and immune responses may increase the levels of plasma haptoglobin in cattle (Cheong et al., 2017).The mean concentration of haptoglobin in our study was not significantly different between Dinoprost treated pyometric cows and saline treated pyometric cows at the time of treatments and 7 days later.Melendez et al. (2004) injected two doses of PGF 2α 8 h apart on day 8 post-partum to cows having acute puerperal metritis.PGF 2α could not alter plasma haptoglobin concentration in that study.However, haptoglobin concentration reduced over 4 days after treatments in PGF 2α treated and not treated groups.Perhaps this resulted from greater variability of haptoglobin among animals (Hirvonen et al., 1999).Melendez et al. (2004) stated that if PGF 2α reduced the diameter of uterine horns in cows that developed metritis, it is reasonable to suggest that the size of the uterus decreased, but does not necessarily indicate that the inflammation and infection was resolved.The mean concentration of haptoglobin between pyometric and healthy cows at the beginning of treatments was not significant in our study.It seems that inflammatory response in pyometric cows was not high enough in our study to increase haptoglobin concentrations in affected animals.It has been reported that in pyometric cattle (Huzzey et al., 2009) and mares (El-Bahr & El-Deeb, 2016) the levels of haptoglobin increases in response to uterine contamination in compare to control groups.Taking all of the above into consideration, we suggest that, Dinoprost reduced the uterine diameter and luminal diameter in pyometric cows mostly by its uterotonic effects, since it could not influence plasma progesterone, estradiol, and haptoglobin concentrations.
We analyzed the uterine diameter and luminal diameter changes this time in pyometric cows having no functional corpus luteum (P4 < 1 ng/ml).Although it has been stated that a physiologic basis for the use of PGF 2α in cows without a luteal structure on the ovary has not been established (Benmrad and Stevenson 1986), few studies have shown beneficial effects of PGF 2α treatment in cows without a palpable corpus luteum and/or elevated progesterone levels (Steffan et al., 1984;Young & Anderson 1986).The results showed that Dinoprost treatment in pyometric cows with low progesterone concentration reduced uterine diameter and luminal diameter.This positive effect of PGF2α on uterine involution on cows lacking a functional corpus luteum as found in our study, was already described (Bonnett et al., 1990).Increased uterine contraction and favorable factors involved in uterine defense mechanisms were induced (Mortimer et al., 1984;Bonnett et al., 1990).A single administration of Dinoprost in healthy cows 14 to 28 days post partum improved conception rate, particularly in cows with a serum progesterone value of less than 0.5 ng/ml (Young et al., 1984).Young et al. (1984) and Young and Anderson (1986) stated that this benefit of prostaglandin therapy was not the consequence of luteolysis, but the beneficial effect of PGF 2α administered post partum is rather the result of myometrial contraction and thereby accelerated uterine involution (Gustafsson, 1984;Garcia-Villar et al., 1987).Perhaps PGF 2α has a role in addition to inducing luteolysis in resolving pyometra.In a study with ewes (Wade & Lewis, 1996), exogenous PGF 2α enhanced utero-ovarian release of natural PGF 2α .This shows that an increase in uterine PGF 2α could enhance neutrophil movement to the uterus.A well-documented effect of PGF 2α is its ability to contract smooth muscles (Masoumi et al., 2011) and to increase uterine tone (Lindell et al., 1982).In our study, Dinoprost could not influence uterine diameter and endometrial diameter 35-45 days post-partum in healthy cows.This is in accordance with the results of Guilbault et al. (1988) and Hirsbrunner et al. (2006) who reported no beneficial effects of PGF 2α treatments on uterine involution of healthy cows.Hirsbrunner et al. (2006) evaluated a single dose of PGF 2α on a uterus administered at 21-35 days post partum giving the no size difference a week or fourteen days later.It does not seem that PGF2α treatments would improve uterine involution 35-45 days post partum in healthy cows, because uterine involution is usually concluded around day 45 postpartum (Kiracofe, 1980;Badiei et al., 2014).However, others have reported that in the early post partum period, even a single administration of PGF 2α does accelerate uterine involution and hasten a return to fertile ovarian cyclicity (Gustafsson et al., 1976;Lindell & Kindahl, 1983;Kindahl et al., 1984;Young, 1989).
There was no significant difference in progesterone concentration between pyometric cows that responded to the treatment by reducing the luminal diameter and the group not responding.This is in accordance with Gustafsson et al. (1976) who reported no significant difference of PGF 2α injection on progesterone concentration between the group of pyometric cows that responded to the treatment and the group not responding.However, by most definitions, pyometra is confined to cows with an active corpus luteum, and PGF 2α would cause luteolysis, decreasing progesterone to permit the uterus to resolve the infection (Gustafsson, 1984;Gilbert & Schwark 1992).Mean progesterone concentration was also not significantly different between healthy cows treated with Dinoprost or saline.Mean plasma progesterone concentration at the beginning of treatments was significantly different between healthy cows and pyometric cows.This is in accordance with the most accepted definition of pyometra which is characterized by high levels of progesterone in pyometric cows (Gustafsson, 1984;Gilbert & Schwark, 1992).
Recently Cheong et al. (2017) determined the effects of uterine and systemic inflammatory responses to uterine bacterial contamination at calving in 53 multiparous dairy cows on the growth and ovulatory outcomes of the first dominant follicle postpartum.Interestingly, elevated systemic inflammation (which was characterized by higher concentrations of Haptoglobin) during the early postpartum period was negatively associated with the ovulatory status of the first dominant follicle and reproductive performance of cows.In addition, contamination of uterus with Trueperella pyogenes at 3 weeks postpartum significantly reduced the risk of pregnancy at 150 days in milk (Gilbert and Santos, 2016).Results of the present study showed that Dinoprost injection increased pregnancy rate in pyometric cows which is consistent with previous studies (Mortimer et al., 1984;El-Tahawy et al., 2011). El-Tahawy et al. (2011) reported that treatment with PGF 2α , PGF 2α + oxytetracycline and PGF 2α + cephapirin increased the pregnancy rate by 53%, 75%, and 56%, respectively, relative to control cows.Exogenous PGF 2α induces luteolysis, reduces progesterone, and enables the uterus to resolve infections due to rising estradiol levels.Expulsion of exudate and bacterial clearance of the uterus follow in 90 -100% of treated cases.Results also showed that Dinoporst injection to pyometric cows decreased open days and this was consistent with reports by Mortimer et al. (1984) who indicated that the number of days open for pyometra cows was 98.7 d and for non-pyometra cows it was 77.0 d.Recommended treatments for bovine pyometra included mechanical removal of the mucopurulent material, uterine antibiotic infusion and hormone therapy (oxytocin, estrogen, PGF 2α ) (Roberts, 1971).

Conclusions
It was therefore concluded that 25 mg of Dinoprost administered at 35 -45 days post partum to pyometric dairy cows reduced their uterine and luminal diameter in the presence or absence of a functional corpus luteum.It was also concluded that administration of Dinoprost injection to clinically healthy cows would not have beneficial effects on uterine involution when administered at 35-45 days post partum.

Figure 1
Figure 1 Least Square Mean (±SE) uterine diameter measurements (A) and uterine diameter changes (B) in healthy cows treated with saline (HS), healthy cows treated with Dinoprost (HD), pyometric cows treated with saline (PS) and pyometric cows treated with Dinoprost (PD).

Figure 2
Figure 2 Least Square Mean (±SE) uterine diameter measurements in healthy cows treated with saline (HS), healthy cows treated with Dinoprost (HD), pyometric cows treated with saline (PS) and pyometric cows treated with Dinoprost (PD) with plasma progesterone concentrations less than 1 ng/ml.
Open bars= First Luminal diameter at the time of treatments.Filled bars= second Luminal diameter 7 days after treatments.X axis represents experimental groups.

Figure 3
Figure 3 Least Square Mean (±SE) luminal diameter measurements in pyometric cows treated with saline (PS) and pyometric cows treated with Dinoprost (PD).

Figure 4
Figure 4 Least Square Mean (±SE) endometrium diameter measurements in healthy cows treated with saline (HS) and healthy cows treated with Dinoprost (HD).

Table 1 abc
Pregnancy rate (after first AI), day to first service and open days in healthy and pyometric cows treated with or without Dinoprost Means within a row with different superscripts differ significantly at P <0.05.Healthy cows treated with Saline (HS), Healthy cows treated with Dinoprost (HD), Pyometric cows treated with Saline (PS) and Pyometric cows treated with Dinoprost (PD).