CSU molds test for respiratory disease

CSU molds test for respiratory disease

May 01, 2003
By dvm360.com staff

Fort Collins, Colo.-A new test to determine a horse's level of exposure to strangles is being hailed as "faster and simpler" than traditional methods.

The test, under development at Colorado State University's (CSU) veterinary teaching hospital, is an enzyme-linked immunosorbant assay (ELISA), which would give veterinarians a tool to efficiently assess the horse's risk level by evaluating the animal's blood antibody titers.

"What we hope to achieve with this test is the ability to definitively determine a horse's risk level so that the owner can more quickly make informed health-related management decisions," explains Dr. Ann Davidson, one of the equine veterinarians creating the test.

"One of the challenges in diagnosing strangles lies with horses that are not exhibiting signs of active illness, but are carriers shedding the bacteria. It is often through contact with these shedders that other horses can become infected."

Strangles is a highly infectious disease in horses that affects the upper respiratory tract and the lymph nodes surrounding the throat, causing swelling and abscessation.

The basis of this ELISA method, developed specifically for Streptococcus equi, relies on whether there are antibodies to the bacteria in the blood. If an animal has been exposed, the test would detect those antibodies and would reflect a high titer.

Currently, tests exist only for horses with active signs of disease. The "gold standard" is a laboratory culture of the nasal discharge or abscess material. Another method is a polymerase chain reaction test, or PCR test.

"The advantage to the ELISA test on the horse's serum is that we can now determine those horses who may not have been exposed and are at risk," says Dr. Josie Traub-Dargatz of CSU, another of the test's researchers.

"Once perfected, we hope the test results will be rapid and readily available, making it a very useful tool for equine veterinarians."

The test is funded by a grant from the U.S. Department of Agriculture, the Cooperative State Research Education and Extension Services for the CSU Program for Economically Important Infectious Animal Diseases, and the College Equine Research Advisory Council on the Use of Racing Funds for CSU's College of Veterinary Medicine and Biomedical Sciences.