Veterinarian Lee Miller says he's worried the horse community doesn't know enough about the moldy corn threat this year.
Miller, a vetin Woodsboro, Frederick County, who practices in Carroll, says Maryland horse owners didn't know about moldy corn poisoning during the last outbreak until a dozen horses had died.
Moldy corn poisoning is frustrating for several reasons: It is almost impossible to detect; there are no known preventive measures other than not feeding corn; the disease has been considered incurable; and the animal must be dead to confirm the diagnosis.
Recent weather patterns favor an outbreak of moldy corn: a summer drought, a wet fall and wildly varying temperatures during the fall and early winter.
These conditions foster growth of an invisible toxin in corn, which causes poisoning in livestock, especially horses.
"By the timethe animal shows symptoms, it is too late," says Miller. "Death willusually occur after three weeks or more of feeding the contaminated corn.
"Before dying, the horse will exhibit a change in personality, signs of blindness, loss of appetite, muscle spasms and aggression. Death usually follows within 24 hours."
Miller says several molds are easy to detect in corn with the naked eye or ultraviolet light.Mold in itself is not necessarily toxic; the presence of mold alone does not mean fatal toxins are present.
The highest risk is run bythose who have a corn crib and throw ears of corn to supplement their horses' feed, Miller says.
"The problem is usually pretty localized," Miller says. "Several feed operations have stopped using corn in their mixtures, and that puts you in a quandary because you can't beat corn for energy in the horse's nutrition."
Miller's wife, Marilyn, is a competitive trail rider and depends on corn for her horses'energy needs.
"I checked where we get our feed, and this last batch was made with corn harvested last year, so it should be all right," says Marilyn Miller.
"But the next batch will be made with corn that I don't want to take a chance on, so it will be back to feeding barley," she said.
No reliable testing procedure exists to detect moldy corn poisoning. Tests developed at Penn State University regularly give false positive results.
John Doerr, chairman of poultry sciences at the University of Maryland, says testing there can detect the mold that gives rise to the toxin, but do not confirm presence ofthe toxin itself.
The National Veterinary Service Laboratory in Ames, Iowa, will test corn samples after an animal has died, but this test is difficult and expensive.
Doerr says researchers are working on a simpler, more accurate test. Meanwhile, he avoids feeding cornto his horses.
Miller suggests the following as an alternative horse-feed mixture: 80 pounds of crimped barley and/or oats; 10 pounds of pelleted feed at 38 percent protein; one pound of trace mineral salt; one pound of Di Cal Phosphate and, if desired, eight pounds of molasses.
The University of Pennsylvania's New Bolton Center for Veterinary Medicine, meanwhile, may have made veterinary history recently.
A veterinarian diagnosed a possible case of moldy corn poisoning at a farm where four horses had already died of an undiagnosed illness.
A specimen from one of the dead horses at the farm in Readingwas taken to New Bolton, and the cause of death was found to be moldy corn poisoning.
An ill horse at the same farm was treated aggressively with DMSO, saline solution and Lasix to relieve pressure on the brain. The prognosis is that the horse will survive.