Veterinarians Probe Mysterious Disease in Australia

Additional information was released Dec. 1 by the Hunter Valley Equine Research Centre, a research facility adjacent to Scone racetrack in the heart of the Australian breeding area, concerning a problem that is causing sporadic abortions throughout the area in mid- to late-term pregnancies. This disease has been termed equine amnionitis and fetal loss (EAFL). Some researchers and veterinarians have noted similarities to this problem and mare reproductive loss (MRLS) that hit the United States in 2001-2002.

The HVERC correspondence stated that between March and November 2004, an unspecified number of mares in New South Wales and Queensland suffered abortions due to a similar disease process. A small number of farms suffered devastating losses (15 of 25 mares on one farm), while most affected farms had one or two cases. Preliminary data indicate that 15-20 separate farms might have been affected.

Abortions occurred without any illness in the mare, according to the HVERC. The most consistent pathologic change was inflammation of the amnion and amniotic portion of the umbilical cord, and variable changes were observed in the fetuses. Cases do not have significant involvement of the outer placental membrane (chorion). Bacteria cultured from affected fetuses have included a range of organisms that normally live in soil, on plants, and in water, and that are not typically considered to be the cause of disease in animals (isolates include Microbacterium species, Cellulosimicrobium spp, Athrobacter spp, and Curtobacterium spp).

Similar cases of mare abortion have been reported occasionally from farms in New South Wales over the past several years, including instances where small farms have had more than half of their pregnant mares abort, noted the HVERC.

Although most affected farms reported only one or two cases, examination of pathology records from 2004 indicated that EAFL accounted for up to one third of all abortions in New South Wales in 2004 where a fetus was found and submitted for postmortem, according to HVERC. Across the breeding industry, this meant that EAFL was potentially the most important cause of abortion in mares during the latter half of pregnancy.

The HVERC has initiated an investigation into EAFL and has asked Nigel Perkins, a veterinary epidemiologist with the private consulting firm AusVet Animal Health Services, to lead a team to investigate the condition in a "timely and rigorous manner," noted the correspondence.

The HVERC stated that Nigel has visited farms in the Hunter Valley (the main Thoroughbred breeding center) and Queensland in November 2004 and the following objectives are now being pursued:
1. Develop a case definition to determine if an abortion is due to EAFL or not;
2. Determine the extent and impact of EAFL by reviewing pathology records and visiting studs and mare farms in New South Wales, Queensland, and Victoria;
3. Review known causes of fetal loss in mares and preventive measures designed to reduce the risk of fetal loss in pregnant mares;
4. Deliver a report to the industry by March 1, 2005, to summarize findings from the above activities and make recommendations for 2005 to reduce the risk posed by EAFL, and prepare for further monitoring and investigation if warranted.

Also, a retrospective analysis is being undertaken by Dr. Angela Begg and Dr. Catherine Chicken on abortions in the Hunter Valley.