To:       Kentucky Department of Agriculture, Office of the State Veterinarian
From:   Dr. Michael Odian, Maryland State Veterinarian
Re:      Ongoing Response to EHV at Laurel Park/Pimlico Racetracks
Date:   April 5, 2021

In a light of a recent e-mail sent to Kentucky animal health officials, I am writing to provide updated/clarifying information concerning the situation at Laurel Park and Pimlico racetracks in Maryland. After learning of the first positive sample at Laurel Park Racetrack, our department implemented a purposeful, clear plan based on science and developed in consultation with infectious disease experts. Our decision making has been, and continues to be, based on data analysis from testing results, risk assessment, and veterinary clinical assessment. As the situation evolves, testing data and risk factors are evaluated and the plan has changed accordingly to best mitigate the disease for the Maryland population of equines.

After the detection of a second positive horse in a small barn at Laurel Park, that entire barn’s population was tested. Six asymptomatic horses were found and removed from Laurel Park and placed at a facility in Bowie for isolation. The barn was retested nine days later and another positive was found. This horse was also removed and sent to Bowie. The data from this small sampling showed two important points:

  1. Analysis of the stalling of positive horses shows they were together in a group in the barn thus possibly isolating the nidus.
  2. Testing of the Maryland population supports the theory that 30% of asymptomatic horses can test positive.

During this time, any symptomatic horses at either racetrack were immediately isolated and tested twice. The first test conducted immediately upon detection of clinical signs and the second test conducted 72 hours later. If both tests were negative, the horse would be returned to its barn. Several horses were screened using this methodology, most resulting in two negative tests. One horse did test positive on the second test and was sent to Bowie. Because this horse was isolated, it did not affect the status of the general population. Not performing the second test would have resulted in that horse being returned to the general population, thus causing a reset of the quarantine clock.

On March 22, a symptomatic horse from a larger barn at Laurel Park did test positive on the initial test. This prompted the testing of 120 asymptomatic horses. This round of testing returned 30 positive tests from asymptomatic horses, further proving that the Maryland population of horses supports the 30% theory mentioned above. All of the positive horses were moved to Bowie for isolation.

A 21-day holder order was placed on all three properties, adding to the time already spent in quarantine. After analyzing the data, assessing the risks, and applying veterinary clinical science, the decision was made to separate the Laurel Park and Pimlico properties, take a break from racing, and test only clinical symptomatic horses at the three properties. Using the protocol of testing asymptomatic horses in specific quarantine barns while allowing racing to continue was not helping to mitigate the EHV situation. To continue to test asymptomatic horses, knowing 30% would test positive, would have resulted in a significant portion of the equine population being placed in isolation. This would create greater hardship on the horsemen and racetrack officials managing the horses and would make it extremely difficult to conduct any form of racing. The decision to take a break from racing was based on veterinary science in the best interest of the health and welfare of the horses. A racing horse will be more prone to illness. By taking a hiatus, the horses will be rested and healthier to combat any possible exposure. Separating the properties was done with the intent that positives at one track would not affect the other since there is no intermingling of horses.

In summary, the plan for mitigating the EHV situation in Maryland is proactive and is based on testing and other factors as described.  Any horse showing any clinical signs from any barn, at any of the three properties, will be immediately tested and isolated. A second test will be performed after 72 hours. The testing is not limited to the barns which have been quarantined, but rather the entire racetracks. The entire population is being monitored, including twice daily temperature checks that are documented and inspected by MDA and racetrack officials.  Consequences for not reporting clinical symptoms will be significant.

We are following the 21-day protocol as defined in the EHM guidance for SAHO, in addition to keeping constant contact with the foremost experts in the study of EHV/ EHM. By combining these protocols, Maryland will be testing horses who have the greatest potential to spread clinical disease and monitoring the entire racetrack population.

Quarantine will be lifted after an additional 21 days added to the time already in quarantine from the date of the original positive index horse. Also, the quarantine will only be lifted if no horse tests positive for EHV on the initial test when clinical signs are seen. If a horse does test positive on the initial test, the quarantine clock will be resetFrom the start of the situation to the proposed end, the racetracks will have been in quarantine for close to 40 days.

This is a very dynamic, constantly evolving situation and Maryland will continue to make any needed adjustments to practically mitigate any cases of EHV. We are happy to discuss our process with industry and state partners. We have had an open dialogue with other states such as Pennsylvania, Virginia, and Delaware, as well as the USDA. If there are any additional questions or concerns regarding our response, please do not hesitate to contact me directly.

Dr. Michael Odian
Maryland State Veterinarian
[email protected]
667-500-2942 (mobile)