UK expands research to include cases of pericarditis, unilateral eye problems

Lexington, Ky.-In mid-June, equine practitioners say cases of pericarditisand unilateral eye problems are still impacting a wide range of horse breeds.

About 50 cases for each condition have been identified.

University of Kentucky (UK) reports that testing continues for the mostrecent surge of cases with pericarditis and unilateral eye problems in horses.Officials are trying to clarify any link to Mare Reproductive Loss Syndrome(MRLS), which struck the equine industry in Kentucky and surrounding statesin April. In early June, at least 529 foal losses have now been attributedto MRLS, UK reports.

While the occurrence of MRLS appears to be declining, the pace of theinvestigation has not yet diminished, reports the Kentucky Department ofAgriculture.

Cyanide or cyanogenic compounds from wild black cherry trees are believedto have caused these catastrophic foal deaths and abortions.

The leading hypothesis under investigation at UK on the source of cyanidefocuses on an abundant supply of Eastern tent caterpillars feeding off wildcherry trees due to an early spring, a subsequent cold snap including freezingconditions followed by a drought.

All three climatic events helped set the stage for the catastrophic situationthat has researchers scrambling for answers.

Viral agents, mycotoxins, phytoestrogens and ergot alkaloids have been,for the most part, ruled out. Two genres of bacteria were isolated from78 percent of fetuses. These isolates are Streptococcus species (56 percent)and Actinobacillus species (18 percent). Another 2 percent of cases involveboth species. The isolates are microaerophilic.

Dr. Roberta Dwyer, an associate professor of UK's Gluck Equine ResearchCenter, explains, "There are more than 100 people working on this problemsince it was brought to our attention, and everybody is doing their best.Our number one goal is to find the etiology so that we can figure out atreatment plan and preventive plan for next season and (for) other areasof the country"

Dwyer adds, "This is a very complex problem. It should be lookedat like a great jigsaw puzzle, and if it was an easy jigsaw puzzle, it wouldhave been figured out by now. Just the sheer number of people from multipledisciplines who have come together to solve this problem is testament tohow complex and very unique this is," she explains.

UK research efforts are now focused on pinpointing the source of cyanide.Officials now have to re-confirm reports of cyanide in late term fetusesand trace cyanide back from mares to black cherry tree leaves.

Wilted black cherry tree leaves are known to be toxic to horses and cattle.Wilting of leaves substantially increases the content and/or availabilityof cyanide.

In addition, the role of Eastern tent caterpillars as a potential sourceof cyanide is not yet understood.

Eastern tent caterpillars were reportedly in abundant supply this yeardue to the warmer weather in early spring.