Funds Increased for Nocardioform Placentitis Research

The University of Kentucky's Gluck Equine Research Center has authorized the use of emergency funds to augment existing research efforts into nocardioform placentitis, a bacterial infection related to foal losses from late-term abortions, stillbirths, prematurity, or early neonatal deaths.

Central Kentucky has seen a spike in reported cases of nocardioform placentitis beginning in December when the UK Veterinary Diagnostic Lab reported 28 cases in December and 57 cases in January. Of these reports, 54 have been reported in Fayette County alone.

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During a Feb. 6 board meeting the Gluck Center announced it was activating Koller Emergency Response Funds to supplement existing research efforts and launch new projects to study the disease while it is occurring. Identifying at-risk mares is difficult right now, making it challenging to treat them proactively.

"Many of our farms have experienced little or limited cases while others have noted incidence numbers that would be greater than anticipated," said Dr. Stuart Brown, Gluck Equine Research Foundation board chair and equine veterinarian from Lexington-based Hagyard Equine Medical Institute. "On many farms with the vigilant surveillance associated with farms in Central Kentucky, there are mares that have delivered foals of acceptable size and development from cases that have been identified by farm managers and veterinarians working together to treat suspected cases before foaling. It is these experiences that will help us solve this puzzle and help us understand the incidence of occurrence associated with nocardioform placentitis." 

Given the pressing need to develop better diagnostic tests and preventative strategies, UK is proceeding with new research projects to gain additional information about the mare's response to the bacterial infection. This coordinated effort involves faculty with expertise in reproduction, microbiology, immunology, and pathology, as well as collaborations with clinical partners throughout the region.

"Drs. Barry Ball, Erdol Erol, Rebecca Ruby, Allen Page, Emma Adam, and Jacqueline Smith are leading this research effort, which aims to identify at-risk mares, collect samples from infected mares for further analysis, and continue to screen the identified bacteria for antibiotic sensitivity and resistance," said David Horohov, chair of the UK Department of Veterinary Science and director of the Gluck Equine Research Center.

While it is typical to see a handful of cases each year, an increase in positive cases reported usually only occurs intermittently. The last increased cluster of cases occurred during the 2017 season, and before that, during the 2011 season. While there have been similar numbers of cases reported by the UK VDL compared to the 2011 season, it is important to note that positive cases refer to all samples received, including affected placental tissues, not necessarily the loss of a foal. In fact, in many cases where the placenta might have been affected, the foal was born healthy and unaffected.

The intermittent occurrence of the disease complicates researchers' work to better understand its origin and improve the diagnosis, according to Ball, a Gluck Center faculty researcher specializing in equine reproduction. Nocardioform placentitis diagnoses can be made following pathological examination of the placenta but pre-partum/abortion diagnosis relies on abdominal ultrasonographic examination of the uterus, where changes may only be noted once the disease has progressed significantly.

A retrospective study of on-farm risk factors associated with the 2010-11 series of nocardioform placentitis cases also identified a number of associations that were positively associated with the incidence of the disease, including the farm being categorized as a larger farm with higher mare numbers and higher stocking density. Conversely, longer grazing times during late winter, pre-breeding administration of progesterone to mares, hCG administration post-breeding, and the administration of non-steroidal anti-inflammatories were not noted to be associated with an increased incidence of nocardioform placentitis.

Prior work at the Gluck Center has suggested that a hot and dry fall may be correlated with increases in the disease seen during the following winter and spring foaling season, but more research is needed to confirm what that correlation means.

In the short term, researchers aim to collect as much information as possible while the disease is present, with an analysis of those data to begin as early as summer. In the longer term, the goal of the research efforts is to learn more about the disease and to provide possible diagnostic tests to identify at-risk mares so they can be treated early in the disease and limit any impact on the foal. A sustained research effort is important even in years when the disease is at a low level.

Researchers will be working with participating farms and collecting weekly blood samples from mares suspected of having the disease, as well as samples from control mares from the same farms that don't have the disease. Sample collection would begin at the time of diagnosis and continue until foaling. Additionally, all placentas (affected and control), as well as any euthanized foals or aborted fetuses, will be evaluated at the UKVDL for definitive diagnosis.