The Second Most Common Neurological Disease Diagnosed in Horses

12 Pages·2011·0.68 MB·English

Volume 29 No 2, July 2011 A publication of the Center for Equine Health • School of Veterinary Medicine • University of California, Davis
The Second Most Common Neurological Disease
Diagnosed in Horses
Neuroaxonal Dystrophy/Equine
Degenerative Myeloencephalopathy
by Carrie J. Finno, DVM, DACVIM
Neuroaxonal dystrophy (NAD)
is a neurological disease in
which both the cell body of
the neurons and the axons throughout
the brain and spinal cord undergo
degeneration. Axons are the parts of the
nerve cells along which impulses travel,
so this condition results in abnormal
conduction of nervous impulses and
associated clinical signs defined by a
lack of coordination. The cause of this
degeneration is not understood at this
time.
Neurological abnormalities associated with neuroaxonal dystrophy or equine degenerative myeloencephalopathy
can be subtle and may be missed for years unless the horse is specifically examined for neurological disease. Mild
cases may present with performance-related issues, where the horse is just not performing up to the standard
expected for its breeding and training.
INSIDE THIS ISSUE…
NAD affects horses, humans, dogs, in horses is typified by an overshoot
The Second Most Common
cats and sheep. A genetic basis for the of intended position with the leg. It is
Neurological Disease
disease has been identified in humans sometimes described as an inability to
Diagnosed in Horses .............1
and is suspected in sheep, cats and dogs. judge distance or scale.)
Director’s Message .................2 In horses, NAD appears to be inherited,
as suggested by pedigree analysis Horses suffering from NAD or EDM
Commentary on NAD/EDM
and supported by breeding studies in typically display a symmetric (left to
by Researchers Involved in
Morgan horses. right) incoordination (ataxia) that may be
Neurological Evaluations .....5
more severe in the hind limbs than in the
Anatomy of an Epidemic: Equine NAD is considered the
The 2011 EHV-1 Outbreak.....6 underlying basis of equine degenerative — Continued on page 3
myeloencephalopathy (EDM), a
Everyday Biosecurity Consid-
degenerative and irreversible disease
erations for Your Horse .........9
of young horses characterized by
Biosecurity Measures hypermetria of the limbs. (Hypermetria
for Different Situations ........10
2 - The Horse Report Volume 29, Number 2 - July 2011
D ’ M
irectors essage
Along Comes Another Neurological
Disease
determining possible cause. While familiar with. In terms of its clinical
this sometimes proves successful appearance, I highly recommend
clinically, it haunts the better nature that you avail yourselves of the video
of our medical science conscience. demonstrating the characteristic
And when this treat-and-hope clinical appearance of affected
method is unsuccessful, we may be animals, which is included in the
left with nothing other than a “give electronic version of this Horse Report.
it time and watch for improvement” The electronic Horse Report can be
recommendation. Neither of these found on our website at http://www.
Dr. Gregory Ferraro
situations reflects well on our vetmed.ucdavis.edu/ceh/current.cfm.
professional training and our desire to I predict, like all conditions medical,
Neuroaxonal dystrophy. Just what properly treat the patient and prevent once you start looking for it, you will
further suffering. And yet, part of find it.
we need, another neurological
the modern Hippocratic Oath for
disorder of horses that we don’t
physicians is, “I will not be ashamed A New Position
understand!
to say ‘I know not,’ nor will I fail to call

in my colleagues when the skills of You may have already heard or read
As a long-time equine practitioner,
another are needed for a patient’s that I have been appointed Associate
I am aware of the problems
recovery.” Director of the Large Animal Clinic
veterinarians face to achieve a
in our William R. Pritchard Veterinary
definitive diagnosis in cases of
So if this situation is not bad enough Medical Teaching Hospital. I have
neurological disease. It can be
already, along comes another accepted these new responsibilities
extremely challenging to sort through
neurological disease, whose signs can at the urging of my colleagues here
clinical signs, both subtle and obvious.
be subtle and for which a definitive within the School of Veterinary
When there is mild or subclinical
diagnosis is yet more complicated. Medicine.
disease, it is not easy to discern
Well, better to know the existence
whether the horse is suffering from
of such a disease and to learn to While I look forward to the challenge
a lameness condition or is actually
recognize it from other neurological of making a new contribution to the
neurologic.
conditions we see than to be school, and I am hopeful that I can
completely ignorant. improve and expand the services
In the more obvious cases of ataxia,
of the clinic, I want to assure all of
one must wade through all sorts of
Therefore, this issue of our Horse you who have been so supportive of
procedures and laboratory tests to
Report presents the clinical me during my tenure at the Center
rule out any number of possibilities
entity known as neuroaxonal for Equine Health that I will be no
and establish a definitive cause. This
dystrophy/equine degenerative less attentive to my duties there
process of elimination, however
myeloencephalopathy. While these than I have in the past. The CEH is
thorough, may even ultimately result
two separate but related diseases may my home, and my true passion and
in a “best guess” situation, because
be new to your medical repertory, I will continue to serve its mission
while the evidence may indicate that
NAD/EDM is not a new disease to the best of my abilities. In fact, I
an infective agent may have been or
and has been known to exist in believe that by further integrating the
currently is present within the body, it
other animals and in humans. In functions of the CEH and our equine
does not necessarily confirm that it is
the following pages, we present clinical services we can maximize the
the cause of neurological disease (i.e.,
a description of these diseases, effectiveness of both.
the presence of antibodies for EPM).
their clinical appearance, and some

methods by which you can distinguish
In this framework, we are often
them from the other neurological
forced to try a process of treatment
conditions you may be more
and response as a means of
UC Davis Center for Equine Health
Volume 29, Number 2 - July 2011 The Horse Report - 3
Neurological Disease
Grading System for Ataxia
— Continued from page 1
0 = Normal; no neurological abnormalities identified
1 = Mild and inconsistent abnormalities
forelimbs. Affected horses will often
2 = Mild consistent abnormalities
stand abnormally at rest (see photos),
3 = Moderate consistent abnormalities
either too wide or too narrow, and will
4 = Severe consistent abnormalities
display proprioceptive deficits, which
5 = Recumbent
means that the horses do not know
where their limbs are as they walk.
Quarter horses affected with NAD/EDM may also
be abnormally quiet and dull. This often makes
these horses particularly easy to handle.
Although the neurological status of horses
affected with NAD/EDM remains stable
throughout the course of their lifetime, their
loss of proprioception may make them a risk
to handle on the ground. At this time, we have
only definitively diagnosed NAD/EDM in horses
that were graded as greater than or equal to a
grade 2 out of 5 from the above scale. Any horse
with a neurological score of 2 or greater should
not be ridden and caution should be used when
handling these horses on the ground.
A video showing some of the clinical signs of
This 2-year-old Quarter
NAD/EDM may be viewed in the electronic (Zmag)
horse gelding shows the dull
version of this Horse Report available at mentation (mental activity)
http://www.vetmed.ucdavis.edu/ceh/current.cfm. characteristic of NAD/EDM.
Prevalence
The ataxia observed with NAD/EDM is very similar to that seen with Wobblers
Syndrome, or cervical vertebral malformation/malarticulation (CVM), where
neurological signs are caused by compression of the spinal cord in the
neck, typically due to developmental abnormalities or osteoarthritis. In a
study performed at Cornell University, EDM was the second most common
neurological disease diagnosed in horses.
A 5-year-old Quarter horse mare with the
Cause of Neurological Disease in Horses
abnormal base-wide stance of the forelimbs
characteristic of NAD/EDM.
Disease Number (n=96) Percentage
EPM 32 33
These clinical signs may be subtle and NAD/EDM 23 24
horses should be evaluated walking CVM 11 12
in slow, tight circles and stopping Cervical injury 9 8
frequently, backing, walking with
Other inflammatory
their head elevated, and walking up conditions 5 5
and down hills and curbs. Ataxia Toxicity 1 1
(incoordination) is graded on a
Unknown 15 16
5-point scale:
— Continued on page 4
UC Davis Center for Equine Health
4 - The Horse Report Volume 29, Number 2 - July 2011
Neurological Disease relatively poor concentrations of evaluate the horse for CVM, as these
— Continued from page 3 classical antioxidants and high cases are indistinguishable based on
content of polyunsaturated lipids, clinical signs alone).
which are most susceptible to
Age of Onset and Breeds
oxidation.  NEGATIVE for West Nile Virus.
Affected
In humans, it is difficult to determine Treatment
Typically, horses are affected with
whether the oxidative stress is
NAD or EDM early in life (6-12 months
primary or secondary in many At this time, there is no effective
of age); however, these neurological
neurodegenerative diseases. It treatment for NAD/EDM.
abnormalities can be subtle and may
was previously determined that Supplementation of affected cases
be missed for years unless the horse is
foals with EDM do not demonstrate with Vitamin E does NOT appear to
specifically examined for neurological
significant differences in oral improve clinical cases. In genetically
disease. Mild cases may present with
Vitamin E absorption as compared predisposed animals, supplementing
performance-related issues, where
to normal foals. Overall, there is very broodmares and foals with at least
the horse is just not performing up to
strong evidence that NAD/EDM is 2,000 IU/day of natural alpha-
the standard expected for its breeding
an inherited disorder and it may be tocopherol does appear to result
and training.
that Vitamin E acts as a modifier to in less severe neurological signs
determine the overall severity of the but does not entirely eliminate the
Males and females are equally
disease in horses affected with NAD/ disease.
affected and the disease has been
EDM. This theory has been supported
reported in the following breeds:
by the NAD/EDM research to date. It appears that the disease may be
inherited in an autosomal dominant
 Quarter horses/Paints/Appaloosas
Diagnosis manner, meaning that only one parent
 Haflingers
needs to be affected to produce an
 Standardbreds
Unfortunately, a definitive diagnosis affected foal. Therefore, it is difficult
 Thoroughbreds
of NAD/EDM requires examination to make breeding recommendations
 Pony of the Americas
of the spinal cord on post-mortem until a genetic test is available.
 Lusitano/Andalusians
examination. Without a necropsy Although horses do not appear to
 Morgans
(post-mortem examination), we recover from this disorder, the disease
 Paso Finos
cannot definitively diagnose the is often either non-progressive or
 Arabians
disease. We suspect cases of NAD/ very slowly progressive and horses
 Tennessee Walking Horse
EDM in horses that meet the following do not become substantially more
 Norwegian Fjord
criteria: debilitated during their lifetime.
 Various Mixed Breeds
The neurological deficits present
 Age of onset of symmetric by 3 years of age generally remain
Role of Vitamin E in NAD/EDM
neurologic signs at 6-36 months of unchanged throughout the life of the
age that either stabilize or are very horse.
A Vitamin E (alpha-tocopherol)
slowly progressive.
deficiency has been reported in some
Research at UC Davis
cases of NAD/EDM. Previous research
 History of other related horses that
has concluded that Vitamin E is a
appear to be affected with similar A group of investigators at UC Davis
factor in the development of EDM
signs. has been studying different aspects of
in the first year of life in genetically
NAD/EDM to determine the genetic
predisposed foals. Oxidative stress is
 History of low vitamin E or poor mutation responsible for the disease.
known to be a component in human
nutrition during the first year of life. The investigators include Dr. Carrie
neurodegenerative diseases, including
Finno, Dr. Monica Aleman and Dr. John
Alzheimer’s, Parkinson’s, Amytrophic
 NEGATIVE EPM titer (blood and/or Madigan (neurological evaluations);
lateral sclerosis, multiple sclerosis,
spinal fluid). Dr. Robert Higgins (pathology
and Huntington’s disease. The
central nervous system is particularly
 NORMAL neck x-rays +/- NORMAL
vulnerable to oxidative insult due to — Continued on page 8
myelogram (this is performed to
the high rate of oxygen utilization,
UC Davis Center for Equine Health
Volume 29, Number 2 - July 2011 The Horse Report - 5

Commentary on
Neuroaxonal Dystrophy/Equine Degenerative Myelopathy
by Researchers Involved in Neurological Evaluations
John Madigan, DVM, MS, DACVIM, and Monica Aleman, MVZ, PhD, DACVIM
This Horse Report highlights two degenerative dis- A thorough neurological examination is required to
orders—neuroaxonal dystrophy (NAD) and equine note subtle abnormalities that may set NAD/EDM and
degerative myelopathy (EDM)-- that have been large- CVM apart. It is also essential to rule out other causes
ly overlooked, as evidenced by a Cornell University besides CVM for the observed deficits (e.g., EPM,
study on the causes of neurological disease in horses. equine herpesvirus-1 myeloencephalopathy, trauma,
In that study, NAD/EDM was identified at postmortem among others) with appropriate diagnostic tests. Cau-
examination in 24% of horses with neurological dis- tion must be taken in the interpretation of radiographic
ease, second only to equine protozoal myeloenceph- abnormalities of the cervical vertebral column because
alitis (EPM) and more common than cervical vertebral alterations may be present without causing clinical
myelopathy (CVM). Since that study was conducted in signs. Therefore, radiographic alterations at this level
1978, more current studies are needed to investigate do not always equal CVM.
the prevalence of disease today. Lack of recognition
of the disorder may play a role in the sporadic reports The diagnosis of NAD/EDM presents a challenge in the
found in the literature. living horse because at present the definitive diagno-
sis is possible only through a thorough postmortem
Cervical vertebral myelopathy with all its clinical examination by an experienced neuropathologist since
variants (cervical vertebral malformation/malarticula- lesions could be missed.
tion, cervical vertebral stenotic myelopathy, cervical
vertebral compressive myelopathy, cervical vertebral Keynotes:
osteoarthritis), also known as “wobblers” syndrome, is
a commonly diagnosed disorder that usually presents  Age of onset: Often in young horses but signs may
with symmetrical ataxia (incoordination) of all limbs, not be noted until the horse is started on training or on
tetraparesis (dragging all feet), and proprioceptive more challenging physical activity. Therefore, the first
signs may be noted even in adult horses.
deficits (abnormal placement of feet in the ground).
These gait and placement deficits could be of various
 There is strong evidence of a genetic basis that
grades of severity, from mild to severe.
affects several breeds of horses. However, do not dis-
miss the possibility of disease because it has not been
NAD/EDM can easily be misdiagnosed as CVM
reported in a certain breed.
because the clinical signs may be undistinguishable
from those seen in horses with CVM. Also, the onset of  Low vitamin E is NOT the cause but is considered an
neurological deficits or age when first noted for both environmental factor associated with onset and sever-
NAD/EDM and CVM is usually in the young popula- ity of signs. Supplement pregnant mares and young-
tion (not exclusive for all types of CVM). NAD/EDM sters if the disease is suspected in breeding farms.
may present with other signs such as mild obtunda-
tion (decreased “alertness”) which is not observed  NAD/EDM may look like a “wobbler”; therefore, do
in CVM. Although there is a breed predisposition in not exclude the disease and rule out other disorders.
horses with CVM, both disorders can affect a variety of
 Definitive diagnosis is reached only through a care-
breeds. A genetic basis for NAD/EDM is suspected in
ful postmortem evaluation.
affected breeds of horses.
UC Davis Center for Equine Health
6 - The Horse Report Volume 29, Number 2 - July 2011
Anatomy of an Epidemic: The 2011 EHV-1 Outbreak
O
ther people may be there assembled from diverse origins and Until a new vaccine is developed,
to help us, teach us, guide housed under high-density, stress- however, the best protection against
us along our path, but the ridden, and heavily co-mingling the neurological form of EHV-1
lesson to be learned is always ours. conditions for competition, showing lies in biosecurity strategies: entry
or performance. Risk factors are stress requirements, isolation protocols,
The recent equine herpesvirus-1 (invariably part of traveling to a horse movement restriction, and infection
(EHV-1) outbreak that kept horse show or event), prolonged transport, control procedures.
owners across the country in a state intermingling of horses from diverse
of apprehension for two months is a locations without prior isolation, and A year after the 2006-2007 EHV-1
perfect example of how an infectious high-density stabling in large facilities outbreak, the USDA issued a report
disease is transmitted and spreads like that share a common air space. in which they summarized collective
wildfire. Management practices also add to mitigation experiences and lessons
stress, including shipping, abrupt learned and recommended future
It started at a horse show where a changes in dietary composition, poor needs with regard to controlling
horse was infected with the virus. It infection control, and disruption of EHM in the future. The report was
is unclear whether this horse had established social hierarchies. based on interviews with a number
any clinical signs or whether it was of scientists, researchers and others
subclinically infected (showing no Since currently marketed vaccines are involved in past outbreaks of EHM.
outward signs of sickness). Before not entirely adequate, and reports One researcher stated succinctly, “It
anyone knew, the show was over of neurological outbreaks in fully is important to have a plan for how
and exposed horses returned home, vaccinated horses are common (AAEP, we will manage the next EHM case
unwittingly carrying the virus back November 6, 2007), the highest or outbreak, as there will be another
with them. Over the next 7 weeks we priority and the greatest gap in one.”
watched the numbers rise until the research is in the development of a
virus had finally sickened 90 horses in new vaccine against the neurological In looking back at our very recent
10 states; 13 of those horses died or strain of EHV-1. experience this year, a number of
were euthanized. It could have been defensive measures were undertaken
worse. Currently available treatment includes quickly and in an organized manner,
antiviral drugs such as valacyclovir resulting in efficient handling of the
The neurological form of EHV- and ganciclovir along with supportive disease outbreak to contain it. It’s
1, known as equine herpesvirus care, which were effective in treating worth looking at those measures
myeloencephalopathy (EHM), has horses that were brought to the UC with the idea that individual horse
probably existed for centuries, but Davis Veterinary Medical Teaching owners can learn from this experience
a strain of the virus has evolved Hospital during this year’s EHM and formulate a plan of their own for
(mutated) in recent decades with outbreak. While most of those when the next EHM outbreak occurs.
an increased virulence over that horses survived with this treatment,
seen in the past. Its ability to and most affected horses make a  Health officials at the USDA and
create spontaneous outbreaks of full recovery, a small percentage of CDFA became involved immediately,
neurological disease is concerning to horses can be left with residual signs resulting in swift, organized action
horse owners and veterinarians alike. such as incoordination or bladder to contain sick horses and monitor
incontinence. confirmed cases of EHM.
At greatest risk for this re-emerging
disease are congregations of horses
UC Davis Center for Equine Health
Volume 29, Number 2 - July 2011 The Horse Report - 7
In California, EHM became a and clear communications to the need to impose strict biosecurity
Reportable Disease just this year public via their websites to keep when horses are identified with
(January 2011) so that it is now people informed about the status of suspected or confirmed EHM.
required to be reported to state the disease, the number of infected
officials within 48 hours of diagnosis. horses, and geographical locations  Awareness and understanding
In the past, EHM was considered a involved around the country. of EHM by horse owners and
Monitored Condition as EHV-1 and communities resulted in good
EHV-4 and reportable to the CDFA The CDFA provided open and cooperation in restricting the
within 30 days of diagnosis. This timely communication on the Web movement of horses and in
change was made based on an dedicated to daily EHV-1 status canceling events.
increasing incidence of EHM in the updates for California for the duration
United States over the last decade. of the outbreak. This was extremely
helpful in minimizing rumors and
The change in reporting status for giving people confidence that There is much more the veterinary
EHM in California was a good move the situation was being handled profession does not know about the
considering that California had the effectively. The USDA provided status herpes virus than what it does as it is
largest number of primary-exposed updates on the disease on a weekly one of the more complicated viruses
horses (59) at the Ogden event as well basis, summarizing information to understand. Researchers at UC
as the largest number of secondary- reported on all states that were Davis and elsewhere are working to
and tertiary-exposed horses (628). affected. increase our understanding of this
organism and its disease-producing
Although EHM is not a Reportable  Research into developing ability and from there to begin to
Disease with the USDA, federal improved diagnostic testing for develop much needed vaccines and
officials became involved in a equine herpesvirus paid off. improved treatment.
monitoring role to provide updates
on the outbreak nationwide. New diagnostic testing methods In the meantime, responsible horse
that have become available through owners can familiarize themselves
 Along with the reporting technological advances helped in with the information provided in
requirement, horses with fever providing more rapid confirmation of this Horse Report (pages 9–11) and
and other clinical signs that were infection. The real-time polymerase elsewhere and learn what to do
confirmed positive for EHV-1 were chain reaction assay (RT-PCR) with when the next outbreak does occur.
immediately isolated. Other horses quantitative assessment allows better Understand that the best defense at
that may have been exposed to the characterization of disease stage, the present time is biosecurity and
sick horse were quarantined for a better assessment of risk of exposure learn what that entails. ❄
prescribed period of time. of in-contact horses, and better
monitoring of response to therapy.
A significant improvement noted
in this outbreak over that in 2007 is RT-PCR has recently been used to
that barrier and isolation protocols document differences in EHV-1 viral
were developed based on experience loads in blood and nasal secretions
and were able to be implemented between horses in the febrile (fever)
immediately. This helped in and neurological stages of disease
preventing the spread of infection. and between clinical and subclinical
Biosecurity information also was well cases. These studies found high
publicized on a number of different viral loads in the nasal secretions
websites and in print publications. of animals with neurological signs,
confirming their importance as a
 State and federal officials issued potential source of contagion for
frequent (daily in the case of CDFA) other horses and highlighting the
UC Davis Center for Equine Health
8 - The Horse Report Volume 29, Number 2 - July 2011
Neurological Disease
— Continued from page 4
evaluations); and Dr. Danika Bannasch
(genetic studies with Dr. Finno).
Our research group recently published
a description of NAD/EDM in the
American Quarter horse. Our ultimate
goal is to develop a genetic test to
identify NAD/EDM, which would
enable veterinarians to diagnose the
disease without requiring euthanasia
and assist breeders in selecting
against the mutation. Research into
the genetics of NAD/EDM will not only
provide a diagnostic/preventive way
to test for the disease but will also
give us insight into the mechanism
underlying the degenerative process
and we can begin to consider how
horses affected with NAD/EDM can be
treated effectively.
For further information on NAD/EDM,
please contact Dr. Carrie Finno at
[email protected]. ❄
One of the ways that horses can catch an infectious disease such as EHV-1 is by direct contact
with another horse or with equipment used for an infected horse. It’s best to use separate
water buckets, feed troughs, tack and grooming equipment for each of your horses. If equip-
ment must be shared, it should be dipped in a disinfecting solution (see page 9), washed and
dried before use on another horse.
UC Davis Center for Equine Health
Volume 29, Number 2 - July 2011 The Horse Report - 9
Everyday Biosecurity Considerations
for Your Horse
Recent outbreaks of equine herpesvirus-1 have  Have a policy for your stable for horses that
brought awareness of the need to handle our leave and attend horse events. Horses returning
horses in a manner that prevents transmission of from distant events should have minimal contact
infection. The term for this is biosecurity, which with other horses. Upon returning to the stable,
means taking measures that prevent transmission travel horses should ideally be isolated from the
of an infection to your horse. home stable population for at least 2 weeks.
Two ways that horses and humans may catch  While traveling, if it is known that at the
many infectious diseases are by direct contact and/ event there were sick horses, take your horse’s
or by aerosol spread via the air. temperature twice daily and report a fever (101.5°F
or greater) to the stable manager and your
Direct contact means physical contact with a horse veterinarian.
that has an ongoing active infection or is in the
early incubation period of infection and ready  Avoid petting and touching other horses to
to break with a fever. It is possible, however, to minimize the chance of infecting your horse.
catch a virus or bacteria from a horse without that
horse having a fever or other signs of infection.  Use separate water buckets, feed troughs, tack
Direct-contact transmission can also occur when a and grooming equipment for each of your horses.
person touches a horse and has the virus on their If equipment must be shared, it should be dipped
hands, tack, bridle, saddle pad, bucket or shoe in a solution of 1 part chlorine bleach to 10 parts
and then spreads the infectious agent via use of water, washed and dried before use on another
that contaminated equipment on another horse. horse. Commercial preparations for disinfection
Herpes viruses are largely spread by direct contact. also are available through your veterinarian.
Aerosol spread means that the infectious agent Other biosecurity measures have been delineated
travels through the air and causes infections by by the U.S. Department of Agriculture’s Animal and
breathing the agent in. Most respiratory viruses of Plant Health Inspection Service and are listed on
the influenza group spread this way. Indeed these pages 10-11.
viruses can travel significant distances, depending
on air flow, temperature and other environmental
conditions. Strangles horses may cough and spread
that bacteria throughout a barn or stable. However,
aerosol spread has not been a primary means of
transmission of EHV-1.
Biosecurity Measures
 Keep your horse in a place where direct contact
with other horses is minimal. If there is contact
with other horses, it should be preferably with
horses that do not leave the premises and return
The equine herpesvirus as viewed by
frequently.
transmission electron microscopy at a
magnification of 167,000 X.
UC Davis Center for Equine Health
10 - The Horse Report Volume 29, Number 2 - July 2011
Biosecurity Measures for Different Situations
The following recommendations from the U.S.  If you are going to be working with horses on
Department of Agriculture Plant and Animal Health another farm, wear coveralls or plan to change
Inspection Service are based on the belief that you clothes before returning home to your horses.
are the best protection your horses have. These
guidelines are intended to reduce the chances of  If there are farms you visit all the time and
you can’t change clothes and shoes, be sure their
an infectious disease being carried onto your farm
vaccination program and biosecurity practices are
by people, animals, equipment or vehicles, either
as good as your own.
accidentally or on purpose.
Showing Your Horse For Visitors to Your Farm or Horse
 Use your own trailer whenever possible. Don’t  It is best to have only one public access to your
ship your horses with horses from unknown farms. farm. Mark this as the main entrance.
 Ship only in a trailer or van that has been  Park away from the horses. Doing that will
cleaned and disinfected. If you can “smell horse” help keep disease-carrying organisms from being
in the empty trailer, it has not been cleaned and tracked from car floors or tires to your horses.
disinfected properly.
 Ask all visitors to wear clean clothes and shoes.
 Don’t let your horse touch unknown horses, Give visitors plastic shoe covers or brush dirt off
especially nose to nose. their shoes and spray them with disinfectant.
 Wash your hands, especially after helping other  If you have many visitors such as at a farm tour
people with their horses. or open house, make a footbath for them to walk
through (see inset, page 11).
 Don’t let strangers pet your horse, especially
those with horses at home.
Bringing Horses Back from a Show
 Before leaving the show grounds, clean and
disinfect tack, boots, equipment and grooming  If one or more horses travel to horse shows,
supplies. Brush off dirt or manure; then disinfect all horses on the premises should be vaccinated.
(spray or wipes are easy to take with you). Horses that show can bring home infectious agents.
Discuss with your veterinarian what vaccinations
 When you get home, shower, blow your nose the horses need and how often.
and put on clean clothes and shoes before going
near other horses.  If possible, keep horses that were off the farm
isolated for at least 2 weeks. At the very least, make
sure there is no nose-to-nose contact between
Visiting Other Farms, Horse Shows horses in the stable.
or Auctions
 Have a pair of shoes or boots that you save for
visiting and don’t wear around your own horse or
wear plastic shoe covers.
UC Davis Center for Equine Health