Equine Biological Risk Management
Equine Biological Risk Management









March 2005


Author: Carolyn Hammer, DVM, PhD
Co-author: Stacy Holzbauer, DVM, MPH
Endorsed by:






Center for Food Security and Public Health
2160 Veterinary Medicine
Ames, IA 50011
515-294-7189
www.cfsph.iastate.edu

Equine Biological Risk Management
March
2005
www.cfsph.iastate.edu/BRM

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TABLE OF CONTENTS
Introduction.............................................................................................................. 3

Risk Perception ......................................................................................................... 3

Hazard Identification ................................................................................................. 4

Risk Assessment ....................................................................................................... 4

Risk Management...................................................................................................... 5

General Farm Practices ..................................................................................................... 6

Health Protocols ........................................................................................................... 9

New Introductions and Animals Returning to the Farm..................................................... 9

Visitors and Human Foot Traffic ................................................................................... 11

Disease Transmission Management.................................................................................. 11

Aerosol ...................................................................................................................... 12

Oral........................................................................................................................... 13

Direct contact............................................................................................................. 15

Reproductive ................................................................................................ 16
Fomites...................................................................................................................... 16

Traffic .......................................................................................................... 17
Vector........................................................................................................................ 18

Eliminating the insect .................................................................................... 19
Separating host and vector ............................................................................ 19
Breeding area control .................................................................................... 20
Summary....................................................................................................................... 20

Zoonotic Disease and Health Concerns of Employees......................................................... 20

Risk Communication ................................................................................................ 22

Conclusion .............................................................................................................. 23

Equine Biological Risk Management
March
2005
www.cfsph.iastate.edu/BRM

3
Introduction

Although horses are considered by some to be companion animals, the equine industry
is a major economic force in the U.S. There are 7.1 million people involved in the equine
industry and 6.9 million horses in the U.S. The U.S. horse industry also has a total
impact of $112.1 billion on the U.S. Gross Domestic Product, an amount that is greater
than the motion picture industry. The horse industry is only slightly smaller than apparel
and textile product manufacturing.
Biological risk management (BRM) is an important and complex aspect of rearing
equine. Few farm or facility owners have plans in place or understand the basic practices
that can be implemented to minimize the risk of infectious agents to their animals. This
document highlights the importance of BRM in equine facilities through risk analysis. In
looking at total risk analysis, we will take into consideration risk perception, hazard
identification, risk assessment, risk management, and risk communication.
Risk Perception
Risk perception is what those involved with the operation believe about the real and
potential risks of infectious and zoonotic disease. These perceptions may be influenced
by what has been encountered on the farm in the past, or by what owners, staff and
clients may have read in magazines, in newspapers or on the internet.
Obstacles and challenges to educating about risk management may be encountered.
Many individuals have negative perceptions associated with risk management, most of
which are based on a perceived lack of necessity or on economic grounds. Efforts to
exclude disease are often thought of as costly, cumbersome, and unnecessary if a
complete vaccination program is in place. However, this is not the case. A recent
outbreak at a college facility in Ohio illustrates the need for re-examination of the
commonly held but inaccurate perception that vaccination is 100% effective protection
against disease.
In January and February of 2003 an outbreak of equine herpesvirus type-1 (EHV-1)
swept through the University of Findlay in Ohio. In January, approximately 30 horses
were shipped to the University of Findlay training facility where approximately 145
horses are housed in three connecting barns. Resident horses are vaccinated for
influenza and equine herpesvirus every two months. New arrivals are required to have
been vaccinated 10-45 days prior to arrival at the facility.
By the second week in January, some horses began exhibiting signs of mild depression,
inappetance, and fever. Over the next few days, 118 horses had a fever and 45 horses
had neurologic signs. Equine herpesvirus type-1 was isolated from the ill horses. The
University of Findlay immediately instituted quarantine procedures for the facility, which
remained in effect for 21 days after the last fever was recorded. Fortunately, the
outbreak was confined to the facility and did not spread to nearby areas. Equine Biological Risk Management
March
2005
www.cfsph.iastate.edu/BRM

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Due to the number of animals infected and the design of the facility, it is believed that
the virus spread throughout the facility by aerosol transmission. The exact cause of
introduction of the virus was never determined. In the end, approximately 85% of all
horses at the facility developed a fever, and 14 horses died or were euthanized.
Although outbreaks of EHV-1 are not uncommon, what made this outbreak unusual was
the high mortality rate. Although these horses were vaccinated against herpesvirus,
vaccination does not protect against the neurologic form of the disease. This example
illustrates the need for every facility, regardless of vaccine protocols, to be vigilant about
the management of infectious disease risks.
Hazard Identification
An important step in the process of risk management is the identification of the diseases
most likely to affect an operation. Owners will already have an idea of infectious agents
they have encountered on the farm and may have knowledge of other endemic agents
in the area. Some diseases have widespread geographic distribution and should be
included as potential hazards on any farm list. One must also always be aware of foreign
animal disease, emerging animal disease, bioterrorism, and agroterrorism agents. The
enormous impact of West Nile Virus (WNV) on the equine population is a potent
example of an emerging infectious disease that has now become established in the U.S.
West Nile Virus is a disease that can cause inflammation of the brain and the spinal
cord, and is spread by the bite of an infected mosquito. The disease was previously seen
only in Africa, Asia, and southern Europe. However, this all changed when WNV was
detected in the United States in 1999. In the year 2000, there were 60 confirmed cases
of WNV in seven different states. Of these 60 cases, 37 horses survived and 23 (38%)
died or were euthanized. In 2001, there were 738 cases of equine WNV from 20 states
with an outcome of 32% mortality. By 2002, WNV had spread to 40 states and infected
14,717 horses. The number of WNV cases finally decreased in 2003 to 5,181 due in
part to a vaccine that became widely available in late 2001. West Nile Virus is now
considered endemic in the U.S. This example shows how quickly a devastating disease
can move through a susceptible population and become established in a country.
Risk Assessment
In order to accurately assess the levels of risk in equine facilities, a review of the types
of facilities commonly used to house horses and other equine is in order. According to
the Equine 98 National Animal Health Monitoring System (NAHMS) study, 78.4% of
equine operations have stalls available for their horses. Most operations consist of a
barn or shelter that can be used to confine the horse and is connected to a pasture,
paddock or dry lot that allows the horse to exercise. The number and activities of the
horses are generally what distinguishes one facility from another. Boarding and training
facilities usually have a high