Successful treatment of ascending placentitis in a Thoroughbred mare

Ascending placentitis in mares is 1 of the leading causes of late-term abortions, premature delivery, and neonate morbidity and mortality. 1 A 5 year old nulliparous Thoroughbred recipient mare presented on the 306 th day of pregnancy for vulvar discharge without mammary development. Fetal viability was confirmed by transrectal and transabdominal ultrasonography. An increase in the combined thickness of the uterus and placenta (CTUP [17 mm]), was detected via transrectal ultrasonographic examination, although no discharge was evident on vaginal speculum examination. Based on examination findings, treatment for ascending placentitis was initiated using an established treatment protocol.2  Antimicrobial (24 mg/kg oral sulfadiazine and trimethoprim twice daily), antiinflammatory (8.6 mg/kg oral pentoxifylline twice daily), and tocolytic (0.088 mg/kg of oral altrenogest daily) agents were given. In addition, 10 mg of estradiol cypionate (IM, once every 3 days, 3 doses total) was given, as it had improved clinical outcome of ascending placentitis cases. 3 A decrease in CTUP was observed on transrectal ultrasonographic examination 8 days after initial presentation. However, all measurements did not return to normal limits; therefore, treatment had to be continued. All measurements of CTUP were within normal limits on transrectal ultrasonographic examination 16 days after initial presentation and the ascending placentitis was considered resolved. Transrectal and transabdominal ultrasonographic examination continued throughout pregnancy to monitor fetal health and screen for recurrent ascending placentitis. On 350 th day of pregnancy, the mare delivered a healthy colt and grossly normal fetal membranes. The colt stood and nursed without assistance < 2 hours after parturition. Histopathological examination of fetal membranes demonstrated no evidence of placentitis. This case demonstrated that successful outcomes are possible in cases of ascending placentitis with early detection and aggressive treatment.

Keywords: Mare, ascending placentitis, parturition

References

1. LeBlanc MM: Ascending placentitis in the mare: an update. Reprod Dom Anim 2010;45:28-34.
2. Bailey CS, Macpherson ML, Pozor MA, et al: Treatment efficacy of trimethoprim sulfamethoxazole, pentoxifylline, and altrenogest in experimentally induced equine placentitis. Theriogenology 2010;74:402-412.
3. Curcio BR, Canisso IF, Pazinato FM, et al: Estradiol cypionate aided treatment for experimentally induced ascending placentitis in mares. Theriogenology 2017;102:98-107.

This manuscript was originally published in the journal Clinical Theriogenology Vol 12(3) Sept 2020.  Clinical Theriogenology is the official journal of the Society for Theriogenology (SFT) and the American College of Theriogenologists (ACT).  This content has been reproduced on the IVIS website with the explicit permission of the SFT/ACT.