NAHMS probes equine health status


Fort Collins, Colo. - Old age was the number one cause of death for horses, according to a recently released study of equine health from the United States Department of Agriculture (USDA).

FORT COLLINS, COLO. — Old age was the number one cause of death for horses, according to a recently released study of equine health from the United States Department of Agriculture (USDA).

What's the bad news? Injury/wounds/ trauma (16.3 percent) and colic (14.6 percent) accounted for more than 30 percent of equid deaths.

Table 1: Percent of operations by testing performed during the past 12 months

In early December, the USDA's National Animal Health Monitoring System (NAHMS) published Part I of Equine 2005, an in-depth study of the U.S. equine population.

Part I of Equine 2005 is the study's On-Farm; Part II, due out at the end of January, looks at the population of equines that are moved from place to place for sales, shows and other events.

This is the second in-depth study of the nation's equine population done by NAHMS, the first being Equine '98.

"The goal of the study was not to identify new treatments or outbreaks of disease," reports Dr. Josie Traub-Dargatz, an equine commodity specialist for CEAH, "but rather to estimate the use of various management and control practices."

Equine 2005 On-Farm component collected data on equine health and management practices from a representative sample of operations that have five or more equids in 28 states in four 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); and Central (Illinois, Indiana, Kansas, Michigan, Minnesota, Missouri and Wisconsin).

The 28-state target population represented 78 percent of equids and 78.6 percent of operations with five or more equids in the United States. Interviews were conducted from July 18 through Aug. 12, 2005, and 2,893 equine operations provided data on equine health and management.

Table 2: Percentage of operations by familiarity with EIA

"The main objectives of the Equine 2005 On-Farm component were to gather information regarding methods used by premises with five or more equids related to infection control and to gather information on some selected diseases," says Traub-Dargatz, who also serves as professor of equine medicine at Colorado State University. "There are many interesting findings, and I think they allow the veterinarian to compare his or her clients' methods of infection control to those in the report.

"For example, I found it interesting that in 1998, we had not recognized West Nile virus in the United States, and now vaccination against this disease is more common than vaccination against any other disease for which we have equine vaccines," she says. "I think this illustrates how quickly the pharmaceutical industry and the equine industry responded to a threat to the U.S. equine population."

Traub-Dargatz adds a trends report will be available in late December that will compare other key findings between Equine 2005 and Equine '98.

"There will be a comparison of vaccine use, knowledge regarding some infectious diseases such as equine infectious anemia (EIA) and comparison of percent of operations and percent of equids tested for EIA," she says. "Beyond that, there will be data from other sources than the NAHMS Equine studies included that are pertinent to illustrate changes over time in the equine industry for various equine health issues."

One of the values of the study, Traub-Dargatz says, is that it includes the options for infection control that are being used by a large percentage of the equine operations, as well as where there are opportunities for further advancements.

Table 3: For operations that administered any vaccine during the previous 12 months; percent of operators who administered the majority of vaccines.

Other findings of the Equine 2005 study follow.


Overall, 75.9 percent of operations had given at least some type of vaccine to resident equids during the previous 12 months. A higher percentage of operations in the West region (83.8 percent) had given at least some vaccines to resident equids, compared to operations in the South and Northeast regions (72.3 percent and 72 percent, respectively). The percentage of operations that used a veterinarian to administer the majority of vaccines to resident equids ranged from 69.5 percent in the Northeast region to 35.1 percent in the West region, where most vaccines were administered by operators or equine owners.

Foal deaths

Nearly 5 percent of foals born alive died in the first 30 days. The percentage of foals that died in the first two days and the percentage that died in the subsequent 28 days (age 3 to 30 days) were similar (2.6 percent and 2.3 percent, respectively). For foals born alive that died in the first 30 days, 18.6 percent died due to injury, wounds or trauma not related to birth, 17.9 percent died from unknown causes, and 14.9 percent died because they failed to get colostrum or milk from the mare. Dystocia, trauma or complications at birth, birth defects and digestive problems were also frequently reported causes of death. Other causes of death included predator attacks and adverse environmental conditions.

Table 4: Percentage of operations that administered vaccines for the following diseases to one or more equids during the previous 12 months.

Equid deaths

The highest mortality rates among resident equids over 30 days of age occurred in equids 30 years or older, followed by equids 20 to less than 30 years of age. The leading causes of death were old age (28.9 percent of deaths), injury/wounds/trauma (16.3 percent of deaths) and colic (14.6 percent of deaths) for equids more than 30 days of age.

Lameness, leg or hoof problems accounted for 7.7 percent of deaths. The remaining 32.5 percent included 6.6 percent attributed to unknown causes and individual specified causes — each of which accounted for less than 7 percent of total deaths — such as cancer, digestive problems other than colic and neurologic problems.

About half of large operations isolated or quarantined returning resident equids —either routinely or due to disease or exposure to disease — compared to about one-third of small operations.

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