General and comparative aspects of endometritis in domestic species: A review.

Endometritis is a leading cause of sub- and infertility in domestic animal species. The healthy uterus is colonized by commensal bacteria, viruses and yeast/fungi that represent the nonpathogenic microbiota. A shift in the number or type of organisms accompanied by immune dysfunction, however, may trigger uterine infection and inflammation. Metritis is associated with inflammation of all uterine layers (endometrium, myometrium and perimetrium), whereas endometritis is a more superficial inflammation involving solely the endometrium. Endometritis generally occurs at two time points in domestic animal species, postpartum and postmating. Postpartum endometritis may chronically persist, either as a low-grade disease that often manifests as a vaginal discharge but not a systemic illness (in some species termed clinical endometritis) or sometimes subclinical where features are only detected by endometrial sampling. Contamination of the uterus at the time of mating occurs by direct deposition of semen (ejaculated or artificially inseminated) into the uterus. Improper drainage of the ejaculatory fluid or an inadequate immune response may result in persistent mating-induced endometritis. Both postpartum and postmating endometritis interferes with fertility by creating a suboptimal environment for embryo development and placentation, and chronic endometritis may have an impact on sperm survival and fertilization ability. In the postpartum animal, there may also be changes in milk production and maternal behaviour, which can affect offspring health and survival. Preventive strategies for endometritis largely depend on monitoring their known risk factors, which are sometimes specific with regard to the species. Effective, nonantibiotic therapy for endometritis is not available to date. Overall, extensive research has been performed in cattle and horses to unravel key aspects of endometritis, but in sows and bitches, the available literature is scant. Thus, the need and opportunity to investigate the condition vary considerably among domestic species and necessitate their comparative assessment. This article reviews general and comparative aspects of the diagnosis and classification, pathogenesis, preventive strategies and therapeutics of endometritis in domestic species with a specific focus on cows, mares, sows and bitches.

Evaluation of different point-of-care tests to characterize the vaginal discharge of sows after parturition and parameters' correlation with subsequent reproductive performance.

The lochia is the physiological uterine discharge post-partum, whereas abnormal fluids are often indicators of puerperal disorders in sows, which negatively influence the further reproductive performance. The aim of the study was to characterize the vaginal discharge in sows employing simple and feasible tests and to correlate the evaluated parameters with the subsequent reproductive performance of these sows. The birth process of 48 clinically healthy free farrowing sows was monitored and several parameters characterizing the vaginal discharge such as total amount, colour, amount of cells (somatic cell count) and cell characteristics (cytology) were collected daily from first to fifth day after parturition. Finally, the reproductive performance of the following gestation was evaluated and compared to the characteristics of the lochia. The amount of vaginal discharge was significantly increased on the second (p < 0.01), third (p = 0.019) and fourth (p = 0.011) day post-partum compared to day one. Furthermore, a decrease in the percentage of neutrophilic granulocytes from day one to three (p = 0.038), four (p = 0.038) and five (p = 0.048) post-partum was observed. The percentage of neutrophilic granulocytes in the yellowish vaginal discharge was increased compared to whitish (p = 0.02) or clear (p = 0.027) vaginal discharge. In addition, obstetrics (p = 0.003) and an increased farrowing duration (p = 0.017) significantly increased the amount of vaginal discharge. Sows with a high amount of vaginal discharge had a significant higher body temperature than sows with no (p = 0.014) or low amount (p < 0.01) of vaginal discharge. No correlation was detected between the evaluated parameters of the lochia and the subsequent reproductive performance. It is hypothesised that the amount of vaginal discharge alone is not a predictor for the performance of sows during their next gestation. However, it might serve as indicator for acute endometritis. In summary, the different parameters of the vaginal discharge determined by means of point-of-care tests might be useful to strengthen a presumptive diagnose of endometritis in sows during the first five days after parturition.

Effect of housing conditions, management procedures and traits of the external male reproductive tract on the sexual behaviour of natural mating boars.

Although artificial insemination in pig production is widespread, many farms rely on natural mating (NM). For NM to be successful, adequate sexual behaviour and a sufficient libido level in boars is crucial for appropriate reproductive performance. Therefore, this observational study evaluated the libido level of 59 boars of different breeds used for NM by a scoring system ranging from 0 (no libido) to a maximum of 23 points (perfect libido) and analysed their general and andrological health as well as housing and management factors influencing the libido. The boars showed a mean libido score of 16.7 (SD ± 2.3). Crossbreed (median: 17.5, min: 14.0, max: 21.0) (p < 0.01) and Landrace (median: 17.5, min: 17.0, max: 21.0) (p < 0.05) boars showed significantly higher libido scores compared to Piétrain boars (median: 14.0, min: 13.0, max: 17.0). A non-slippery mating area was found to be positively associated with libido (p < 0.05), whereas disorders such as lameness showed a negative correlation (p < 0.01). In winter, significantly higher libido values (median: 17.0, min: 14.0, max: 21.0) were recorded compared to spring (median: 16.0, min: 11.0, max: 21.0) (p < 0.05). In addition, high number of supports by farmers during natural mating and frequency of use for NM and for stimulation of artificially inseminated sows did not negatively influence the libido score. No significant correlation between the satisfaction of the farmer about the libido level of the boars and the evaluated libido score was detected. This is the first study investigating the effect of housing conditions and management procedures on the libido of boars used for NM under field conditions. The findings may therefore help to establish a successful mating management for herds applying NM on a regular basis. A systematic evaluation of the libido score is needed to detected boars with low libido levels, because it is often overlooked by the farmers. Moreover, genetics, general health condition and flooring in mating areas turned out to be critical parameters that influence the libido score of boars used for NM and therefore should be considered when examining natural mating on farm.

Influence of different sow traits on the expulsion and characteristics of the placenta in a free farrowing system.

The last phase of parturition is the detachment and expulsion of the placentas and should not exceed a duration of 4 h after the birth of the last piglet. At present, only a small amount of information is available about factors influencing the expulsion of the placenta, especially in sows accommodated in free farrowing systems. This study aimed at investigating the influence of sow traits on placenta expulsion in a free farrowing system in Switzerland. In this study, 48 crossbred sows were included and the following traits of the sows were investigated: Backfat thickness, birth induction with at least 116 days of gestation with prostaglandin F2α, placenta parts and weight, placental efficiency (quotient of litter weight and placental weight) and expulsion of the first placenta part in relation to the last piglet. In addition, the farrowing process and litter parameters were recorded. The piglet expulsion duration (260.3 ± 199.5 min) and placenta expulsion duration (388.7 ± 300.2 min) were positively correlated (p = 0.001). Sows that expelled the first placenta part simultaneously with the last piglet or even before the last piglet was born showed a significantly prolonged piglet expulsion duration in comparison to sows that expelled the first placenta part after the last piglet was born (305 ± 216 min vs. 139.0 ± 34.9 min; p < 0.01). Sows with 2-4 placenta parts had a significantly shorter farrowing (292.91 ± 117.92 min) and placenta expulsion duration (160.73 ± 104.00 min) than sows with 5-7 placenta parts (634.63 ± 330.79 min farrowing duration; 460.77 ± 337.32 min placenta expulsion duration) and sows with 8-10 placenta parts (599.00 ± 138.20 min farrowing duration; 438.43 ± 117.98 min placenta expulsion duration) (p < 0.01). Sows with placental efficiency <5 were characterized by a significantly higher number of liveborn piglets compared to sows with a placental efficiency ≥5 (17.1 ± 2.7 piglets vs. 13.6 ± 2.8 piglets; p = 0.002). This is the first study that evaluated the placental characteristics in a free farrowing system and compared it with specific sow traits. Especially, the expulsion of the first placenta and the number of placenta parts could be a reliable parameter to detect sows with obstetric problems and therefore enable improvement sow and piglet health.

Ultrasonographic examination of postpartum uterine involution in sows.

Physiological uterine involution during the puerperium period is essential for sow reproductive health. Uterine involution in sows has mainly been described using macroscopic and histological examination after slaughter. The aim of this study, therefore, was to describe the continuous regression of uterine diameter from day 2-14 after parturition and on the day before weaning using ultrasonography in sows housed in a free farrowing system and in farrowing crates. Diameter of three uterine cross-sections was measured at 24 -hs intervals in 46 sows housed in a free farrowing system in Switzerland and 49 sows housed in farrowing crates in Germany. Overall, there was continuous regression of uterine diameter during the lactation period in both groups. Median diameter of the uterus decreased from 32.4 mm (min: 18.6 mm, max: 52.3 mm) on day 2-9.0 mm (min: 7.6 mm, max: 12.7 mm) on the day before weaning (on average 30 days p.p.) in sows housed in free farrowing systems. Median diameter of the uterus of sows in farrowing crates decreased from 38.5 mm on day 2 (min: 21.6 mm, max: 56.3 mm) to 10.1 mm (min: 8.8 mm, max: 13.6 mm) the day before weaning (on average 29 days p.p.). Interestingly, parity, obstetrical intervention and administration of oxytocin was not associated with the decrease of uterine diameter during the study period. In summary, the ultrasonic examination is a suitable method to evaluate diameter of the uterus during the puerperium period in sows and to describe uterine involution in vivo.

Multicystic degeneration of the Cowper's gland in a Large White boar.

The present report describes a case of multicystic degeneration of the Cowper's gland in a 1.3-year-old purebred Large White intact boar with reduced fertility in Switzerland. Based on the case history, a general physical examination, an andrological investigation and a transrectal ultrasonography combined with a subsequent thorough pathological examination including histology a multicystic degeneration of the Cowper's gland were diagnosed. The case indicates that cystic degeneration of the bulbourethral gland should be contemplated in the differential diagnoses of andrological disorders even though it has not been described in pigs so far. While selecting breeding boars, a morphological check of the bulbourethral gland can be performed, since degeneration of the gland would potentially have an impact on future fertility.