The National Animal Health Monitoring System’s (NAHMS) Equine ’98 Study was designed to provide the horse industry with information on the nation’s equine population for education and research. Sponsored by the USDA Animal and Plant Health Inspection Service (APHIS) Veterinary Services, NAHMS used a sample of operations from 28 states from 1,136 participating operations with three or more horses on Jan. 1, 1998. Questionnaire data were collected on site from June 15 through Sept. 11, 1998. One-half of the blood samples were collected during this time period, and the other half were collected from Nov. 11, 1998, through Feb. 26, 1999. A total of 25 states participated in the blood collection phase of the ’98 study.

The results from the 1998 study have been released over the past year, and the results from "EVA: Equine Viral Arteritis and the U.S. Horse Industry" were recently released. Some of the information provided by the study follows:

  • Overall, 59.4% of operations had never heard of EVA, while 13% knew some basics or were knowledgeable of the disease. The Western region had the lowest percentage (4.9%) of operations that know some basics or were knowledgeable of EVA.
  • The percentages of operations that were familiar with EVA were highest in the racing (31.9%) and breeding (31.3%) categories of horse use and lowest in the farm/ranch category. Familiarity with diseases often is based on need to know, and to date, EVA has primarily impacted the breeding and racing industries.
  • Overall, only 1.6% of operations had a policy of vaccinating some or all resident horses against EVA.
  • Only 0.9% of operations indicated that they had tested any horses for EVA in the previous 12 months. The highest (1.9%) of operations that tested was in the Southern region.
  • Of the operations that used stallions for breeding in the previous 12 months, only 3.0% shipped semen within the U.S. and 0.1% shipped semen internationally. Just over 1% of operations with breeding stallions indicated they tested all of these stallions for EVA. Two states (New York and Kentucky) have EVA programs, and 0.4% of operations had stalliions enrolled in one of these programs.
  • Only 2% of horses lacking a history of vaccination against EVA were seropositive.

From NAHMS Equine ’98 Study, For more information, see the NAHMS web site at

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