Volume 22 No 3, July 2004

CEH HORSEREPORT

A publication of the Center for Equine Health, UC Davis School of Veterinary Medicine Infectious Disease and Equine Public Health

everal years ago, a meeting defi ned and delineated the prob- One of the fi rst organized scien- was held at the Center for lem. It also provided a stimulus for tifi c teams was charged with the SEquine Health to discuss the insightful discussion and set in mo- investigation of EPM to determine future direction of equine infec- tion a process of planning that took when, where, and how horses tious disease research. In atten- several months to complete. At the become infected with the protozoal dance were faculty researchers conclusion of this process, the Cen- agents (Sarcocystis neurona and with expertise in a number of Neospora hughesi) that cause the scientifi c disciplines from the UC disease. A fi ve-year research plan Davis School of Veterinary was outlined, and the work pro- Medicine. The intention gressed through the support of the group was to of the Wayne and Gladys identify both tradi- Valley Foundation. Bet- tional and innova- ter diagnostic tests also tive investigative were pursued, resulting strategies that in the development of could signifi cantly an immunofl ourescent enhance the antibody test (IFAT) to global effort to more accurately identi- control the spread fy exposure of the horse of infectious diseases to EPM-causing agents. in the horse and other The development of this animal species. test has given veterinarians a In spite of the fact that in tool that can rule out the disease 1968 the U.S. Surgeon General as a cause of neurological defi cits declared that the war on infec- in horses. Recently, this group was tious disease had been won, the ter for Equine Health had a research able to identify and experimentally UC Davis group knew otherwise. strategy for achieving signifi cant They knew that of the worldwide new knowledge about the spread — Continued on page 3 human deaths each year, fully of disease among horses and other one-third were caused by infec- species, including humans. Groups tious disease. They knew that were organized to investigate INSIDE THIS ISSUE… more people are suffering from specifi c diseases such as Equine tuberculosis today than ever Protozoal Myeloencephalitis (EPM) Directorʼs Message ...... 2 before. They knew also that the or West Nile Fever. Others were West Nile Virus Update ...... 5 traditional weapons of vac- charged with broader mandates, Bernice Barbour Lab ...... 6 cination and antibiotic therapy such as studying genetic variations CTF Scholarship Winners ...... 8 were becoming less effective in within a virus strain that determine preventing infection, and that the its ability to cause disease in the CEH Horses for Sale ...... 8 spread of so-called “third world horse. The plan also included Fatal Parasite Found in diseases” among the modern an innovative group of scientists Horses and Sea Otters...... 9 industrialized countries whose mandate was to study patho- Equine Viral Arteritis ...... 10 was now a fact of life. genic mechanisms common to all This initial infectious diseases, rather than to Dollars for Davis Benefi t ...... 11 meeting study any specifi c disease itself. Equine Rescue E-Mail Forum ... 12 2 - The Horse Report Volume 22, Number 3 - July 2004

DIRECTOR’S MESSAGE Equine Public Health: For the Good of All

not only possible but probable. The results of such an epidemic could be devastating, considering that today’s industry is entirely dependent on the free movement of horses for compe- tition. Faced with these facts, each of us within the equine industry has a solemn responsibility to become in- volved at some level with the main- tenance of equine public health. The individual horse owner, trainer, Dr. Gregory L. Ferraro rider, or veterinarian must pay at- tention to reported disease condi- ublic health officials are often tions, abide strictly with regulations quoted as saying, “Nobody designed for their control, and report Pcares about public health until outbreaks of disease whenever they there is an epidemic of a serious occur. Equine industry officials must infectious disease.” People gener- become involved in the regulatory ally are concerned about their own processes for disease management health and that of their families but and control and must support pro- seldom think about the importance grams needed to define and deter the of maintaining the health of the broader Each of us within the equine industry community. Yet, in today’s world of rapid has a solemn responsibility to become international travel, involving the move- involved at some level with the mainte- ment of large numbers nance of equine public health. of humans, animals, and foodstuffs, the global spread of disease is an ever- spread of disease. Medical scientists increasing reality. with expertise in both infectious This phenomenon is of no less disease and equine health must work concern to equine health. Horses diligently to identify pathogenic today are second only to humans in agents that pose a potential threat causing agents (viruses, bacteria, worldwide travel. Consequently, and identify methods for their con- protozoa) develop their potential the chance for exposure to infectious trol and eradication. health threat to horses. As you will agents abroad and the possibility for The Center for Equine Health see in the pages to follow, we have introducing disease into the home and its cooperating researchers have made significant progress toward environment upon return are causes been focused on this issue for several understanding the delicate balance for concern. There are currently 17 years. We have worked to develop between host, pathogen, and en- diseases listed with the World Health techniques for identifying serious vironment, which determines the Organization that are considered to pathogenic agents, to determine rate and virility of infection within a be potential threats to global equine the extent of their virulence, and to local community and throughout the health. Under these circumstances, design strategies and methods for world. an outbreak of infectious disease their control or prevention. We have To a large extent, these discover- that could impair the free movement achieved a better understanding ies and the disease control methods of horses, or stop them entirely, is of how, why, and where disease- that they produced have been made

UC Davis Center for Equine Health Volume 22, Number 3 - July 2004 The Horse Report - 3 possible by the visionary leadership Disease Laboratory. Supported by a Infectious Disease — and financial support of several phil- New Jersey-based foundation of the Continued from page 1 anthropic organizations to whom the same name, this research program horse is of particular interest. You is designed to study the very basic reproduce an antigen that is secreted have read and will continue to read mechanisms within the host, agent, by EPM-causing parasites. This about the West Nile Virus epidemic and environment that allow for the discovery may ultimately lead to a in the United States. Studies pertain- infection and transmission of patho- test to positively identify the pres- ing to this virus have been ongoing genic agents in humans and other ence of the parasite in sick animals. at the Center for Equine Health since animals, using diseases of the horse The work of these investigators has its initial outbreak in Queens, New as experimental models. In this issue now taken on even more impor- York, thanks to the support of the of the Horse Report we will present tance since Sarcocystis neurona was Stans Foundation. Our work with some of the remarkable discoveries recently linked to increasing death the long-standing problem of Equine this group has made due to the inno- rates among sea otters along the Protozoal Myeloencephalitis (EPM) vative vision not only of its scientists California coast. has been supported by the Wayne but of the Bernice Barbour Trustees Equine viral disease is another and Gladys Valley Foundation. Our as well. area of focus for Center for Equine School of Veterinary Medicine has So please, read with care and con- Health scientists. Due to the initial an internationally recognized Equine cern the information we are presenting support of horse enthusiasts Bernard Viral Disease Laboratory, due to the here. Whether this is your first foray and Gloria Salick, the Equine Viral foresight and generosity of Bernard into the subject of equine public health Disease Laboratory was created and Gloria Salick. This laboratory or not, we hope you will conclude that through the Center for Equine Health has undertaken a major equine viral everyone who cares for and enjoys and charged with the investigation disease research initiative made pos- the pleasure of horses must become of global viral diseases. This group sible by the generosity of the Harriet involved with this issue. The Center for has identified the genetic variation E. Pfleger Foundation. Equine Health, as well as every other and virulence determinants for most One of the most unique of the institution or agency concerned with strains of Equine Arteritis Virus in infectious disease research initiatives disease management, needs your con- the world. They have developed a established by the Center for Equine cern, input, and support if we are to be network of international collaborat- Health has been the development of successful in protecting the worldwide ing scientists and have conducted in- the Bernice Barbour Communicable health of horses. ❄ depth studies of viral diseases such as African Horse Sickness and West Nile Virus in southern Africa, where both diseases are prevalent. Thanks in large part to the Stans Founda- tion, researchers in the Equine Viral Disease Laboratory have been able to study and track the progress of West Nile Fever across the United States. They are now conducting a prospective study on the emergence of the virus in California and are well positioned to contribute significantly to its control. This group has now partnered with the Harriet E. Pfleger Foundation on a long-term viral dis- ease initiative designed to advance the identification and control of viral diseases that could negatively affect the international health, transport, and commerce of horses. One of the first projects of this initiative is the

— Continued on page 4

UC Davis Center for Equine Health 4 - The Horse Report Volume 22, Number 3 - July 2004

Infectious Disease — of equine infectious diseases, they bold, it was not without risk, but the Continued from page 3 were interested in finding a way to gamble has already paid off with utilize the CEH’s recognized exper- some startlingly new insights. These development of a vaccine to prevent tise to serve a broader interest in will be described in more detail in African Horse Sickness, a serious understanding the disease process the story on page 6. and fatal disease of horses that ap- in all animals. What resulted was What these last several years of pears to be on the verge of spreading the creation of the Bernice Barbour work at the Center for Equine Health globally. Another project involves Communicable Disease Laboratory has demonstrated is that strategic the identification and study of re- (BBCDL). It was designed to create long-term planning, combined with spiratory viruses that are constantly an intellectual research umbrella dedicated researchers and commit- present in the stables of athletically to study the basic mechanisms of ted philanthropic support, can result competitive horses to find out which environmental pathogen transport, in remarkable scientific achieve- of them are important to the dynam- infection, and host immune response ment. The ultimate benefit of this ics of respiratory disease outbreaks. common to all disease-producing innovative approach to veterinary Perhaps the most unusual of agents, regardless of species af- research is the dramatic improve- the infectious disease study groups fected. Their concept was that if we ment to the health and welfare of is one that came about through the could understand the primary way animals. Its concept and implemen- visionary leadership of the Bernice in which microbes go about their tation is, truly, the scientific wave of Barbour Foundation. The trustees of business, then we could develop the future. ❄ this animal philanthropic foundation disease-prevention strategies effec- came forward and requested that the tive in all animals. In the BBCDL, Center for Equine Health develop a diseases of the horse are used as truly new and innovative approach a model to study factors common to the study of communicable dis- to the infectious processes of all eases in animals. While they were diseases. While the concept behind supportive of our efforts in the field the BBCDL was truly innovative and

UC Davis Center for Equine Health Volume 22, Number 3 - July 2004 The Horse Report - 5

HELPFUL TIPS

West Nile Virus Information Update

est Nile Virus (WNV) has made its appearance in California this year. As of June 29, 2004, the virus has Wbeen found in birds and mosquitoes in six Southern California counties. To date, the following cases of West Nile Fever have been reported:

8 confirmed human cases and 1 confirmed equine case in San Bernardino County 2 confirmed human cases in Los Angeles County 1 confirmed human case and 3 confirmed equine cases in Riverside County

Horse owners should prepare for what is to be an escalating problem by ensuring that all horses are properly vaccinated and that all standing water is removed or treated for mosquito larvae. The Centers for Disease Con- trol and Prevention have predicted that California will be the epicenter for WNV in 2004.

All dead birds, especially crows, jays, and raptors, should be reported to the Dead Bird Hotline. Call the toll- free number 877-WNV-BIRD (877-968-2473) or send an e-mail to: [email protected].

WNV typically increases in incidence through the summer months to peak infection rates in August and Sep- tember. The fact that the disease has not been diagnosed in your area yet does not mean that you will not be af- fected. Infected birds are capable of spreading WNV northerly throughout their Pacific migratory flyway at any time and should be expected to do so by late summer or fall. Horses exhibiting neurological signs of disease, whether vaccinated or not, should be examined by a veterinarian.

Vaccine Recommendations

There are currently two fully approved West Nile vaccines available for horses. Each requires an initial series of at least two vaccinations, followed by periodic “booster” injections. The Center for Equine Health recommends that horse owners keep their horses properly vaccinated at all times against this disease. We suggest that you consult with your personal veterinarian regarding which vaccine is most appropriate for your particular horses and how often you should administer booster vaccinations. For more information on West Nile Virus, visit the following Web sites:

http:///www.westnile.ca.gov http://www.cdfa.ca.gov/ahfss/ah/pdfs/WNV%20fact%20sheet%20fc5.pdf

Current Research

The UC Davis Center for Equine Health, the Center for Vector-Borne Disease, and the Wildlife Health Center have been conducting a prospective study on the epidemiology of West Nile Virus in cooperation with the Sacramento-Yolo Mosquito Control District. The research project began in May 2003 and will continue for the next two to three years. The study is designed to define and describe the naturally occurring spread of the West Nile Virus through susceptible wildlife and domestic animal and bird populations. Mosquitoes and selected bird and animal populations are being monitored for exposure to the virus and incidence of clinical disease. This research is being supported by the Stans Foundation.

UC Davis Center for Equine Health 6 - The Horse Report Volume 22, Number 3 - July 2004

The Bernice Barbour Communicable Disease Laboratory

he Bernice Barbour Communi- animal body (host) utilizes to pro- cable Disease Laboratory was tect itself against invading microbial Testablished four years ago with enemies. The ultimate purpose of the purpose of taking a new approach this investigative track would be to to the conduct of infectious disease determine how the body’s own physi- research. The laboratory created a ological processes could be utilized “research umbrella” under which to protect and defend itself from inva- medical scientists with differing skills sion and disease. and expertise were brought together The Bernice Barbour Com- as a team. This team has embarked municable Disease Laboratory has on long-term, multi-tasking studies made considerable progress toward of how and why pathogenic micro- reaching these goals over the last four organisms are able to survive, infect, years, beginning with their envi- and cause disease among the animal ronmental research. Waterborne species of the world. The laboratory transmission of infectious agents was designed to focus on the basic remains an area of public health that mechanisms by which all infectious is inadequately addressed both in The Bernice Barbour Foundation was diseases are produced, rather than the United States and internation- established by the late Bernice Wall on individual diseases exclusively. ally. The virulence of waterborne Barbour of New Jersey, who devoted Although the research would be infectious microorganisms depends her life to making the lives of animals conducted using pathogens that are on effective transport to susceptible happier and healthier. common in horses, the studies would hosts. Our research group hypoth- be directed toward demonstrating esized that the probability of water- eventually lead to preventing water- infectious processes that are char- borne transport of microbial patho- borne zoonotic diseases. acteristic of all animal diseases and gens is governed by factors that load The study of infectious organisms thereby have broad relevance. a watershed with adequate numbers has been directed to understanding The scientific plan was to con- of infective pathogens, processes the characteristics within families of duct research along three specific that attenuate or remove the patho- microbes that determine their abil- investigative tracks. (1) Studies of the gen load, and the efficiency of the ity to cause disease. Researchers are life of infectious microbes outside hydrodynamic transport system into also attempting to identify critical the sick animal (environment). An which it is deposited. To investigate aspects of natural transmission and attempt would be made to determine that theory, the researchers studied genetic evolution that result in the which factors allow an infectious naturally occurring phenomena to development of virulent characteris- agent (protozoa, bacteria, virus, etc.) develop laboratory models to demon- tics in strains of previously innocuous to survive in the environment, repro- strate the attenuation and inactivation microorganisms. One sophisticated duce, and present itself in sufficient after environmental contamination of model that is currently being used numbers at a specific place and time groundwater with different strains of in this research is the manipulation to cause disease. (2) Studies of the the protozoal parasite Crytosporidium and modification of infectious cDNA means utilized by microorganisms parvum. They found that the likeli- clones of virulent and nonvirulent to invade the host and cause disease hood of the waterborne transmission strains of Equine Arteritis Virus. If we (pathogen). Why, for example, are of this disease-producing organism can determine in the laboratory those certain agents able to get past the depends on its ability to avoid irre- basic phenotypic viral parameters body’s protective barriers and cause versible binding to soil and/or stream that affect infectivity, then this knowl- damage when other, more abundant sediments. This and other continuing edge could be applied toward the microbes cannot? (3) Studies of the studies, together, represent one of the development of improved diagnostic complex system of immunological most comprehensive evaluations of testing, vaccines, and potential new and inflammatory processes that the the fundamental processes that could therapies.

UC Davis Center for Equine Health Volume 22, Number 3 - July 2004 The Horse Report - 7

The goal of the host research ini- tiative is to identify host (horse) genes and their disease response activities that are critical to both disease resis- tance and susceptibility. These stud- ies are aimed at developing improved diagnosis, treatment, and prevention Meet Liam of disease and have taken a two- pronged approach. One is patho- gen-host gene investigations. These have been advanced by the advent of sophisticated real-time polymerase chain reaction and microarray (gene chip) technologies for the horse. The other equally promising area is the development of highly relevant equine cell culture systems that can be used to evaluate the response of the horse’s first-line defense cells for invading pathogens. This “horse in a Petri dish” provides a reliable and reproducible assay system for the study of significant disease processes and avoids the use of live horses. The humane aspects of this development are more than obvious. While the foregoing description of this research program may seem esoteric or enigmatic at first reading, one must realize that the acquisition of basic scientific knowledge is an absolute prerequisite to the develop- ment of new and improved methods Liam with his mother Laura. for the management of disease in all species of animals. The cure and orn on March 21, 2004, Liam is the first-ever draft horse to prevention of disease within your Bbe bred and conceived at the Center for Equine Health. His horse requires prior study and labo- mother Laura, a purebred Belgian mare, was bred to the CEH’s ratory analysis of multiple medical now-famous Belgian sire Spanky as part of our ongoing research hypotheses. The Bernice Barbour project on Chronic Progressive Lymphedema in draft horses. Communicable Disease Laboratory Liam was named in honor of the firstborn son of one of the is devoted to discovering new knowl- research scientists on the project, Dr. Hilde De Cock, a Belgian edge regarding the basic principles national herself. that govern all aspects of infection and disease, because it is this knowl- Liam will be monitored throughout the initial two years of his edge that will provide the basis upon life to determine when the first stages of the disease occur in which all future therapeutic advance- these horses. It is suspected that early subclinical manifestations ments will be made. As one cannot of this degenerative condition may occur early in life and long travel to space without the knowl- before any of the classically described skin lesions are evident. edge of the laws of physics, one can- not cure without the why, where and Liam has become quite a popular figure at the CEH and is seen how of microbial pathogenics. ❄ frequently in the company of the Center’s director.

UC Davis Center for Equine Health 8 - The Horse Report Volume 22, Number 3 - July 2004

CEH Congratulates Winners of California Thoroughbred Foundation Scholarships

alifornia Thoroughbred Foundation scholarships have been awarded to fourth-year veterinary students CJennifer Donofrio and Ryan Carpenter. Jennifer received her undergraduate degree in biology at UC Riverside and a Master’s degree in veterinary science at the University of Ken- tucky. She is interested in a variety of aspects in veterinary medicine, among which are lame- ness, reproduction, anesthesia, foals, and sport- horses. It may be diffi cult for her to choose her fi eld of specialty in the not-too-distant future.

Ryan earned his undergraduate degree in ani- mal science at Cal Poly. Perhaps his particular interest in veterinary orthopedics is a refl ection of his personal enjoyment of snowboarding, as he will be pursuing an internship in that fi eld followed by a residency in surgery. Congratula- tions to these two outstanding students! Jennifer Donofrio and Ryan Carpenter with Times Diamond Lil and her foal.

CEH Horses for Sale on the Internet

he Center for Equine Health has horses for sale on Ttheir Web site. Choose from many quality AQHA, APHA, APhC, and TB yearlings and weanlings (coming soon). Sires include Masterful Advocate (TB), winner of $723,650 in 26 starts; San Par, own son of Peppy San and winner of over $16,000 in major cutting horse events; Zippin Bonana Flash, sire of many pleasure horses; and Playboy Sailor, who has competed and won in reining and now has sired his fi rst foal crop. Our mares include own daughters of The Investor, Zippos Mr. Good Bar, Leaguers Sandman, Ima Freckles Two, and Nu Cash. Don’t miss out! Call us at (530)752-6433 or, better yet, view the horses at:

http://www.vetmed.ucdavis.edu/ceh/Horses4Sale/ horse4sale Progeny of Playboy Sailor (L) and Zippin Bonanza Flash (R).

UC Davis Center for Equine Health Volume 22, Number 3 - July 2004 The Horse Report - 9

Fatal Protozoal Parasite Found in Both Horses and Sea Otters

quine protozoal myeloen- deaths have been reported previ- is concentrated in filter feeders. cephalitis (EPM) is a neuro- ously, but the number of otter deaths Investigations also are continuing Elogical disease that occurs during this particular time period into the epidemiology of EPM in when protozoal parasites infect greatly exceeded that in previous horses. In horses, researchers have and invade a horse’s central ner- years, and localized clustering of described the incidence of EPM, vous system. Infection with this Sarcocystis neurona infections has the geographic distribution of the parasite results in characteristic le- not been documented before. Many disease, risk factors associated with sions in the brain and spinal cord otters stranded alive had clinical signs infection, vulnerability of fetuses in and causes incoordination and the womb, muscle atrophy. The two proto- and the age zoal parasites have been identified at which as Sarcocystis neurona and, less horses commonly, Neospora hughesi. are more Opossums are considered the likely to be definitive host for Sarcocystis exposed to neurona, shedding the infective the parasite sporocysts (egg-like stage of de- under field velopment) in their feces. Horses conditions. become infected by ingesting food The or water that has been contami- case of nated with opossum feces con- Sarcocystis taining the infective sporocysts. neurona The definitive host for Neospora appear- hughesi has not been identified. ing in two In approximately 2 to 4% of suggesting brain damage. To date, af- quite different species underscores cases, the sporocysts ingested by fected otters have tested negative for the importance of understanding a horse migrate from the intes- several pathogenic viruses, including the basic mechanisms by which tinal tract into the bloodstream West Nile virus. The harmful algal all disease spreads. While not of- and cross the blood/brain barrier, bloom toxin, domoic acid, may have ficially part of the Bernice Barbour causing disease. There, they at- contributed to the deaths of a few sea Communicable Disease Labora- tack the horse’s central nervous otters, as well as a second protozoal tory (BBCDL), the research group system. The onset of the disease parasite, Toxoplasma gondii. Sea ot- investigating the occurrence of Sar- may be slow or sudden, and the ter mortality returned to more normal cocystis neurona in horses (equine signs vary depending on the type levels by May 2004. protozoal myeloencephalitis) of damage to the central nervous Investigations into the sea otter exemplifies the founding principles system. If left undiagnosed and deaths are being conducted. Sci- of the BBCDL. Their knowledge untreated, EPM can cause dev- entists believe that the Toxoplasma of the mechanisms by which EPM astating and lasting neurological parasite, found in cat feces, ends occurs in horses, the relationship deficits. up in the ocean through freshwater of the disease to the environment, In April 2004, an unusually runoff. The parasite may then be con- and the diagnostic testing methods high number of dead or stranded centrated by ocean filter feeders such they have developed can all be ap- sea otters from the Morro Bay area as shellfish, which are then eaten by plied to the disease caused by the were found to be infected with the the otters. Something similar may be same parasite in sea otters. ❄ same parasite that causes EPM in happening with Sarcocystis neurona, horses, Sarcocystis neurona. Such but researchers do not yet know if it

UC Davis Center for Equine Health 10 - The Horse Report Volume 22, Number 3 - July 2004

Equine Viral Arteritis: A Continuing Threat

quine viral arteritis (EVA) is a in Thoroughbreds and rare in many the stallions imported into the U.S. contagious disease of horses that other breeds. Although EAV infection The majority of these stallions come Ecauses fever, ocular and respira- is relatively common in Standard- from Europe, where EAV infection is tory signs, swelling of the limbs, and bred horses, there are few reports of stringently regulated, so that carrier abortion. Although the disease is not any recent outbreaks of EVA in this stallions are identifi ed and precluded fatal, it tends to occur as an outbreak, breed. Because of several high-pro- from movement within the Union. affecting multiple horses. It is usually fi le outbreaks of EVA in racing Thor- Coincidentally, about 20% of Europe- attributable to the movement of horses oughbreds in the last 25 years, the an Warmblood stallions imported into on racetracks or stud farms. Venereal incidence of EAV infection has been the U.S. are seropositive to EAV—that transmission occurs through the con- minimized through proactive vaccina- is, they have a signifi cant increase taminated semen of carrier stallions. tion of colts prior to puberty to prevent in antiviral antibodies in their blood, EVA occurs throughout demonstrating prior ex- the world, but the disease posure to the virus—and is of increasing concern to a substantial proportion the U.S. horse industry. It of these presumably is caused by the equine are carriers of the virus. arteritis virus (EAV), which In the absence of any is shed in the semen of national EVA certifi ca- persistently infected “EAV tion program in the U.S., carrier” stallions. It is owners can unwittingly transmitted to mares during import Warmblood stal- natural or artifi cial breeding. lions that are shedding The virus is then spread by EAV and thus pose a sig- aerosol (through breath- nifi cant threat to horses ing and sneezing) from in this country. acutely infected mares to Breeders who intend susceptible horses, young to import stallions into and old, to precipitate an the U.S. should be aware outbreak of EVA. Such an of this, especially if they outbreak is characterized by are importing Warm- any combination of effects: blood stallions from abortion of pregnant mares, Europe. The occurrence of severe pneumonia in foals, and Because the carrier stallion clearly is the EAV infection is highest among a systemic infection in adult natural reservoir of equine arteritis virus, selected populations of horses horses that may be accompa- in portions of continental nied by fever, hives, nasal and control of these animals is critical to the Europe, whereas it is uncom- ocular discharge, and swelling of control of EVA. mon in England, Australia, New the lower body parts. However, Zealand, and South Africa. the vast majority of horses with Producers should confi rm that EAV infections do not show signs of them from becoming carriers. The any stallions they intend to import are the disease, and carrier stallions are situation with Warmbloods is prob- screened for antibodies to EAV in a otherwise healthy. Only stallions can lematic, as discussed below. reputable laboratory prior to importa- become persistently infected carriers The United States is the only tion. Carrier stallions typically have of EAV. country with a substantial horse high levels of neutralizing antibodies The occurrence of EAV infection industry that does not have a national in their serum. Unfortunately, results varies markedly between horse breeds program to regulate the importation from serological tests for EVA fre- in the United States. Infection is most of stallions and semen with regard quently differ among different testing common in Standardbred horses and to EVA. Warmblood breeds consti- laboratories. Therefore, we recom- Warmbloods, whereas it is unusual tute a very substantial proportion of mend that testing be done in interna-

UC Davis Center for Equine Health Volume 22, Number 3 - July 2004 The Horse Report - 11 tional reference laboratories such as at Weybridge, England; the Gluck Equine Center at the University of Kentucky; and the National Veterinary Services Dollars for Davis Benefit Ride Laboratory in Ames, Iowa. These are all international reference laboratories, Saturday, July 24, 2004 - 10:30 am and their results should be compara- East Bay Mud Trails ble. Semen from stallions also can be evaluated for the presence of EAV by Upper San Leandro Reservoir, Moraga virus isolation and polymerase chain reaction (PCR assay), and these assays he Moraga Horsemen’s Association also should be conducted at interna- invites you to ride the beautiful Moraga tional reference laboratories. T hills on Saturday, July 24. Profits from the Because the carrier stallion clearly donations raised will benefit the UC Davis is the natural reservoir of EAV, control Center for Equine Health. of these animals is critical to the con- trol of EVA. Specifically, the carrier You may elect to compete in the optional Trail state can be prevented by prepubertal Trials competition. Approximately six miles of vaccination of colts, but once infected, moderate to steep terrain on mostly fire trails will be available to both there is no treatment for the carrier competitors participating in the Trail Trials event as well as to those state other than castration. Thus, wishing only to ride for pleasure. carrier stallions should be evaluated regularly to determine whether or not Minimum donation is $25.00; optional Trail Trials entry fees are they still are shedding virus, and they $18.00 for adults and $13.00 for juniors. Under age 18 must be ac- must only be bred to mares who are companied by an adult rider throughout the ride. Lunch will be avail- immune either through vaccination able by pre-order for $5.00 (BBQ tri-tip sandwich with fixin’s). For or prior natural exposure. In addition, more information, contact Linda Ostman at 925/376-9472. immune mares that are bred to shed- ding stallions should be isolated for 2 to 3 weeks after breeding before they Required Equipment: are mixed with other mares, especially Helmets are recommended for all riders. Trail Trial competitors must pregnant mares. EVA is readily man- have a saddle, bridle (any type), and halter with lead rope or halter/ aged through an integrated strategy bridle. Hoof pick must be carried on the ride, and a canteen is highly that includes screening of all horses recommended. prior to importation, vaccination of prepubertal colts, and the strict breed- Ride Information: ing segregation of any carrier stallions. Gate to open at 7:30 am. Registration starts at 8:00 am. Staggered Outbreaks of EVA remain uncom- starts begin at 9:00 am. Water available at ride site and on the trail for mon, but the consequences of indi- horses. vidual outbreaks can be devastating through losses associated with abor- Directions: tion, foal pneumonia, and persistent From Highway 24, take Orinda exit. Follow signs to Moraga. You will infection of unvaccinated colts. And, be on Moraga Way. Go approximately 4 miles to signal by Jack-in- because other countries regulate the the-Box and turn right on Canyon Road. Go over bridge and look for movement of animals based on their driveway on left at mailbox for 423 Canyon Road, about 1/8 mile after prior exposure to EAV, the movement bridge. Please close the gate. If needed, overflow parking available at of seropositive animals from the Unit- Valle Vista staging area, next driveway up Canyon Road. ed States may be problematic, even for competition. Owners of breed- Weather Conditions: ing stallions and importers of equine Please note that if the weather is extremely hot with high fire danger, semen should thoroughly monitor for the parks could be closed. If so, we will have to cancel this event. If the presence of EAV in order to avoid questionable, call 925/376-9472. precipitating an outbreak of EVA. ❄

UC Davis Center for Equine Health Volume 22, Number 3 - July 2004 The Horse Report - 12

Equine Emergency and Disaster Response CEH HORSEREPORT Symposium Generates E-Mail Forum ©The Regents of the University of California July 2004 t the request of participants in the Equine Emergency and Disaster Response Symposium on April 24, the UC Davis Veterinary Emer- Center for Equine Health A (530) 752-6433 gency Response Team has set up an e-mail forum for people to ask www.vetmed.ucdavis.edu/ceh questions of each other and bring rescue groups together to communi- cate. The aim of this forum is to promote preparedness among people Director: Dr. Gregory L. Ferraro and their communities. e-mail: [email protected]

The e-mail address for this forum is: Writer/Editor: Barbara Meierhenry e-mail: [email protected] [email protected] Management Services Officer: For further information, visit the VERT Web site at: Katie Castelli e-mail: [email protected] http://www.vmth.ucdavis.edu/home/VERT/ Dean, School of Veterinary Medicine: Dr. Bennie I. Osburn

The Center for Equine Health is supported with funds provided by the Oak Tree Racing Associa- tion, the State of California Pari-Mutuel Fund WHOAH, CEH IS ON LINE! and contributions by private donors.

Visit our Web site at: The University of California does not discrimi- www.vetmed.ucdavis.edu/ceh nate in any of its policies, procedures or practic- es. The University is an affirmative action/equal If you are accessing the Horse opportunity employer. Report from our Web site and no longer want a paper copy, The information you provide will be used for just let us know . . . save us the University business and will not be released postage; the horses will ben- unless required by law. To review your record, contact Advancement Services, 1480 Drew efit! Send an e-mail request to: Avenue, Ste. 130, Davis, CA 95616. A portion [email protected] of all gifts is used to defray the costs of admin- istering the funds. All gifts are tax-deductible as prescribed by law. CEH HORSEREPORT Nonprofit Org. Mail ID#1415 U.S. POSTAGE Center for Equine Health PAID School of Veterinary Medicine UC Davis University of California One Shields Avenue Davis, CA 95616-8589

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