Focal MucoidPlacentitis: Advancing Diagnostic and Therapeutic Frontiers
This unique form ofplacentitisis challenging for both breeders and veterinarians to manage. | Adobe StockNocardioformplacentitis(NP)now more descriptively referred to asfocalmucoidplacentitis(FMP)is a unique form of equineplacentitisthatremainsone of the most enigmatic challenges for breeders and veterinarians. Firstidentifiedin 1985, FMP has since occurred episodically with outbreaks in 1998, 1999, 2011, 2017 and 2020. The most recent surge in 2020 was reported in Central Kentucky and in the Mid-Atlantic region. Sporadic cases of FMP have also been reported in South Africa, Italy, Australia,Braziland New Zealand. Affected mares maysufferlate-term abortions or give birth to small, weak, stunted foals due to placental insufficiency. These outcomes are not only devastating for breeders and owners but also impose a substantial economic burden on the equineindustry. At the University of Kentuckys Equine Reproduction Laboratory, our research focuses on improving our understanding of and management for this disease by developing innovative diagnostic and therapeutic strategies.The Enigmatic DiseaseThe route of infection for FMPremainsone of the most significant mysteries surrounding the disease. Unlike ascendingplacentitis, which originates from ascending bacterial infection through the cervix, FMP is characterized by unique mucoid lesions typicallylocatedat the base of the uterine horns. These lesions are often covered ina thick, tan, mucoid material and are sharply demarcated from healthy tissue. How bacteria reach this siteremainsunknown.The condition has been thought to be associated with soil-dwellingnocardioformbacteria such asCrossiellaequiandAmycolatopsisspecies, though other non-nocardioformbacteria like Mycobacterium species andPantoeaspecies have also been isolated from clinical cases. Yet despite these associations, experimental attempts to induce the infection in mares by intrauterine inoculation ofCrossiellaequiat breeding and in pregnant mares viaoral,intravenousand intranasal routes have been unsuccessful. Therefore, the pathogenesis of FMPremainsobscure. What is clear, however, is that the environment plays a role. Outbreaks have repeatedly followed latesummerscharacterized byunusuallywarm and dry conditions.Advancing Diagnostic FrontiersDetecting this condition at an early stage is crucial for effective treatment. While transabdominal ultrasound is a primary tool, it can miss early or small lesions because of the limited area that can be visualized in a large pregnant uterus. By the time overt clinical or imaging abnormalities are detected, the disease is already advanced, reducing treatment efficacy and increasing the risk of pregnancy loss.To address this limitation, our laboratory is pioneering the use of blood-based proteomicsan advanced approach that enables comprehensive analysis of the circulating protein profile. Preliminary studies haveidentifieda panel of proteins that issignificantlyaltered in mares with FMP compared to healthy controls. We are currently expanding this work to verify andvalidatethe most informative biomarkers, focusing on those with the highest sensitivity,specificityand diagnostic accuracy. The development of a reliable blood-based screening test wouldrepresenta major advancement, allowing veterinarians toidentifyat-risk mares earlier and with greater confidence. Earlier detection would, in turn,facilitatetimelytherapeutic intervention before the disease progresses,ultimately improvingpregnancy outcomes.Advancing Treatment FrontiersCurrent treatment protocols arelargely empirical, as it is not yet fully understood which medications effectively penetrate the thick mucoid material to reach the bacteria. New research efforts led by Dr. Rebecca Ruby at the UK Veterinary Diagnostic Laboratory are focusing on measuring antibiotic penetration andidentifyingwhich drugs best reach the target site. Furthermore, byutilizinghigh-resolution RNA sequencing, we at the Equine Reproduction Laboratory are investigating the genes involved in placental inflammation.Identifyingthese on/off switches for inflammationspecifically Toll-like receptors (TLRs)may allow for the development of targeted therapies that complement existing anti-inflammatory and antimicrobial treatments.How the Industry Can HelpSolving the mystery of FMP requires a partnership between researchers and the horse industry. The industry can contributeby:1.) Sharing samples: Providing blood samples andsubmittingplacentas from suspected cases to diagnostic laboratories forresearch, 2.) Maintaining detailed records: Accurate mare histories help researchers correlate disease patterns with potential risk factors, and3.)Participating in surveys: Answering surveys helps map the geographical spread andidentifycommonalities among impacted farms.Looking AheadWhile FMPremainsa complex puzzle, our efforts to develop reliable diagnostic biomarkers and targeted therapeutics aim to fill critical gaps in the management of equine FMP. Our goal in the Equine Reproduction Laboratory is clear: to improve live foal rates and pregnancy outcomes for mares and reduce the substantial economic loss associated with this disease.This is an excerpt from Equine Disease Quarterly, Vol. 35, Issue 2, funded by underwriters at Lloyds, London, brokers, and their Kentucky agents. It was written byHossam El-Sheikh Ali, DVM, MVSC, PhD, Dipl. ACT, associate professor of equine reproduction, at the University of Kentuckys Gluck Equine Research Center, in Lexington.
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