United States Department of Agriculture • Animal and Plant Health Inspection Service • Safeguarding American Agriculture 

Veterinary Services 

Centers for Epidemiology and Animal Health March 2007 

_______________________________________________________________________________________________________________________ 

Trends in Equine Infectious 

Anemia Testing (EIA), 

1998–2005 

One goal of the U.S. Department of Agriculture’s (USDA) 

National Animal Health Monitoring System’s (NAHMS) 

Equine 2005 study was to compare trends in EIA testing 

in the United States from 1998 to 2005. 

For the Equine 2005 study, NAHMS collected data 

on equine health and management practices from a 

representative sample of operations with 5 or more 

equids in 28 States within 4 regions.* The 28-State 

target population represented 78.0 percent of equids and 

78.6 percent of operations with 5 or more equids in the 

United States. Interviews were conducted from July 18 

through August 12, 2005, and 2,893 equine operations 

provided data on equine health and management. 

 Some estimates in this information sheet are 

compared to estimates from Equine ’98, NAHMS’ 

previous study of the U.S. equine industry. For the 

evaluation of changes and trends, the data used to 

generate estimates based on the Equine ’98 study were 

re-analyzed to represent operations with five or more 

equids present on January 1, 1998. Therefore, estimates 

for comparing the two study periods are based on 3 

points of commonality: same 28 States, data collection 

performed by National Agricultural Statistics Service 

enumerators, and same reference population of 5 or 

more equids. 

 Of operations participating in the Equine 2005 study, 

40.3 percent identified their primary function as 

“farm/ranch” and 37.0 percent identified their primary 

function as “residence with equids for personal use.” A 

resident equid was defined as an equid that spent or 

was expected to spend more time at the operation than 

at any other operation, whether or not it was present at 

the time of the interview. The operation was its home 

base. 

____________________________________

*Regions: 

West: California, Colorado, Montana, New Mexico, Oregon, 

Washington, and Wyoming

Northeast: New Jersey, New York, Ohio, and Pennsylvania

South: Alabama, Florida, Georgia, Kentucky, Louisiana, 

Maryland, Oklahoma, Tennessee, Texas, and Virginia 

Central: Illinois, Indiana, Kansas, Michigan, Minnesota, Missouri, 

and Wisconsin

EIA testing 

 The percentages of operations that tested at least 

one equid for EIA were similar in 1998 and 2005, with 

58.7 percent of operations testing at least one equid in 

1998 and 54.1 percent doing so in 2005. The overall 

percentages of resident equids tested on all operations 

during the previous 12 months were similar in 1998 and 

2005 (36.6 and 37.6 percent, respectively). For 

operations that tested at least one resident equid during 

the previous 12 months, the percentages of equids 

tested were similar at 55.6 percent in 1998 and 59.1 

percent in 2005. 

 The official number of EIA tests reported by USDA 

has increased over time, particularly since the late 

1990s. However, the percentage of horses tested for EIA 

based on estimates from the NAHMS studies (1998 

versus 2005) changed only slightly. There are several 

potential explanations. For example, horses that had 

more than one test in a year would create discrepancies 

in estimates. In addition, based on estimates from the 

Census of Agriculture from 1997 to 2002, the equine 

population has increased. This increase could have led 

to more tests being performed, while the overall 

percentage of horses tested remained the same. Finally, 

the NAHMS studies do not estimate health issues for all 

sectors of the equine industry. For example, horses at 

racetracks are not included in the studies. An increase in 

testing in that sector of the industry would have led to an 

increase in the number of tests performed, which would 

not be captured in NAHMS percentage estimates. 

Similarly, when comparing 1998 and 2005 estimates, 

NAHMS included only operations with five or more 

equids. An increase in percentage of horses tested on 

operations with fewer five equids is not reflected in the 

NAHMS trends estimates. 

 The average cost of testing for EIA per test, 

including call fee or cost of transporting the equid, 

increased from $22.95 in 1998 to $27.33 in 2005, or 19.1 

percent. 

 The primary reasons for testing for EIA in 2005 

cannot be directly compared with the primary reasons in 

1998 because “facility (e.g., boarding, breeding) 

requirement within State” was listed as an option for 

testing in 2005 but not in 1998. For 2005, show or event 

requirement within State was cited by 38.0 percent of 
United States Department of Agriculture • Animal and Plant Health Inspection Service • Safeguarding American Agriculture 

operations as the primary reason for testing, followed by 

interstate movement (between two or more States) and 

personal knowledge (19.2 and 18.8 percent of 

operations, respectively). Facility requirement within 

State was the primary reason given for EIA testing by 

11.1 percent of operations and change of ownership 

within State was reported by 8.2 percent of operations. 

Only 1.0 percent of operations reported suspicion of 

equine illness and 0.3 percent of operations gave 

international movement as the primary reasons for EIA 

testing. Finally, 3.4 percent of operations cited “other” 

as their primary reason for EIA testing. 

For operations that tested for EIA, percentage of 

operations by primary reason for testing: 

Percent Operations 

1998 2005 

Primary Reason 

for Testing Pct. 

Std. 

Error Pct. 

Std. 

Error 

Change of 

ownership 

within State 

14.5 (2.2) 8.2 (0.7) 

Show or event 

requirement 

within State 42.2 (3.0) 38.0 (1.3) 

Facility (e.g., 

boarding, 

breeding) 

requirement 

within State N/A* 11.1 (0.8) 

Interstate 

movement 

(between two or 

more States) 21.5 (2.5) 19.2 (1.1) 

International 

movement 1.3 (0.6) 0.3 (0.1) 

Personal 

knowledge 12.1 (1.8) 18.8 (1.1) 

Suspicion of 

equine illness 1.7 (0.8) 1.0 (0.3) 

Other 6.7 (1.4) 3.4 (0.5) 

Total 100.0 100.0 

*Facility not an option in 1998. 

_______________________________ 

For more information, contact: 

USDA:APHIS:VS:CEAH 

NRRC Building B, M.S. 2E7 

2150 Centre Avenue 

Fort Collins, CO 80526-8117 

970.494.7000 

E-mail: NAHMS@aphis.usda.gov 

http://nahms.aphis.usda.gov 

#N472-0307 

____________________________________

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