The unidentified disease that has been afflicting wild horses in Hawaii over the past 2 months is closer to being identified because of tests from labs across the country.
The Hawaii Department of Agriculture (HDOA) reports that 15 horses in the Waipio Valley have been afflicted with the same unknown illness that causes severe nerve damage. The symptoms begin to show in the horses’ hind legs, affecting their gaits until eventually they lose all mobility.
Thirteen of the horses have died from the illness. One of these horses, which was dying, was euthanized for testing.
Veterinarian Tim Richards examined one of the animals and said he had “never seen a clinical presentation like that before,” according to West Hawaii Today.
Kelleyerin Clabaugh, another veterinarian, tested blood samples from the sick horses and echoed Richards’ statement that the disease was unique and unheard of.
There was speculation that rat lungworm (RLW) might be behind the illness, but Jason Moniz, program manager of HDOA’s Animal Disease Control Branch, says that there was only a “very low quantity of RLW DNA” found in samples tested from the euthanized horse’s brain, cerebral spinal fluid, heart and lung.
Lab work did detect sarcocystosis, which can cause weight and muscle loss in the hind limbs. Some types of it can cause equine protozoal myeloencephalitis, but this type was not found in the samples.
“There are other species of sarcocystis; however, one in particular, sarcocystis fayeri, [which] can cause illness similar to what has been seen in the Waipio horses,” says Moniz. “Further evaluation of tissues will be conducted and additional test(s) will be sought out to rule this in or out as a cause of the illness.”
The people involved in studying this disease are also testing for pesticides and botulism and determining what plants were in the euthanized horse’s stomach. Researchers are also utilizing histopathology, the study of how diseases have altered tissues.
A complete list of all the tests and findings can be found on the HDOA’s website.