Equine Health Update Issue 1 Volume 16 - Page 9

Infected birds develop a high viremia and serve as the source of virus to infect mosquitoes. The incubation period in horses is 7-10 days and clinical signs in horses consist of low-grade fever, anorexia, and lethargy progressing to neurologic signs that may appear suddenly and worsen over the ensuing days. Fortunately, once infected, horses due to low virus levels. may be useful as an early marker of placental insult. In addition to endocrine monitoring, measurement of acute phase proteins in blood may also be a useful biomarker for placentitis in mares. Serum concentrations of acute phase proteins are elevated when inflammation is present. This group of proteins is mainly produced by the liver in response to an inflammatory stimulus. The major acute phase protein in the horse is serum amyloid A (SAA), whereas the minor acute phase proteins include haptoglobin and fibrinogen. In ongoing research at the Maxwell H. Gluck Equine Research Center, mares with experimentally induced placentitis have a rapid and dramatic elevation in SAA within two days after intracervical inoculation with Streptococcus equi subspecies zooepidemicus. Although SAA appears to be a very sensitive indicator for acute bacterial placentitis, it is also a very nonspecific indicator, as many other acute inflammatory conditions may result in an elevation of SAA. Ultimately, it appears likely that more than one biomarker may be required for accurate and early detection of placentitis in the mare. Ongoing research will address these needs and evaluate the utility of these markers in mares under field conditions. Since the appearance of WNV, cases have continued to be diagnosed in horses in the United States and Kentucky. As of November, Kentucky officials reported 12 cases of WNV for 2013. These cases occurred in 10 Kentucky counties. None of the 12 horses were vaccinated against WNV. Seven were Quarter Horses, two were Standardbreds, and the remaining were a Paint Horse, a Percheron cross, and a Rocky Mountain Horse. Ten of the horses survived, and two were euthanized. In 2012, 13 cases of WNV were reported versus one case in 2011. The 2012 cases were centered in Central Kentucky while in 2013 the cases were in Western Kentucky. Eastern equine encephalomyelitis (EEE) is uncommon in Kentucky. This viral disease is also mosquito transmitted and is characterized by clinical signs similar to those seen with WNV. Eastern equine encephalomyelitis is considered to have a mortality rate approaching 90 percent. In 2013 in Kentucky, two cases of EEE were reported. One case was in a 10-year-old Tennessee Walking Horse and the other in a 17-year-old Quarter Horse. Neither had been vaccinated against EEE, and both horses died as a result of disease. The American Association of Equine Practitioners includes WNV and EEE in their list of core vaccinations for horses. The other core vaccinations are Western equine encephalomyelitis, tetanus, and rabies. CONTACT: Drs. Barry Ball (859) 218-1141 b.a.ball@uky.edu Igor Canisso, and Mats Troedsson Maxwell H. Gluck Equine Research Center University of Kentucky Lexington, Kentucky Additional information can be found at http:// www. k yagr.com/statevet/equine -infectious- diseases. html#west. Equine Encephalitis Cases West Nile virus (WNV) causes disease in humans, horses, and birds. It is a mosquitoborne virus that first appeared in the United States on the East Coast in 1999. Many horses were infected and died during the following years, and WNV is now considered endemic in the US. CONTACT: Dr. Neil M. Williams (859) 257-8283 nmwillia@uky.edu Veterinary Diagnostic Laboratory University