Ehv 1


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Dr. Jen led a discussion about EHV-1, explaining what the disease is and what to do about it.

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Ehv 1

  1. 1. Update on Equine Herpes Virus-1<br />Jenifer R Gold DVM ACVIM<br />Mountain Horse Medical Center<br />May 2011<br />
  2. 2. Update for Utah<br />As of noon today <br />4 quarantined facilities (Box Elder, Davis, Kane and Utah Counties)<br />7 Confirmed cases on the quarantined facilities<br />8 Suspect cases on the quarantined facilities<br />2 cases euthanized due to recumbency/inability to rise<br />
  3. 3. Update for Outbreak in General<br />Confirmed EHV-1 or equine herpes myeloencephalitis (EHM) have been reported in 9 states (AZ, CA, CO, ID, OR, TX, UT, WA)<br />Arizona has 1 confirmed EHM and 1 euthanized.<br />California has no new confirmed cases since 5/23/2011. So far they have 18 confirmed EHM cases. These cases came from Odgen UT (16) and Kern County Cutting Event (2), Bakersfield, CA. 1 case has been euthanized.<br />Colorado has 9 confirmed cases of EHV-1. 2 of those horses were euthanized after showing severe neurological signs. 22 suspect cases. (not confirmed) 12 quarantine and hold orders in 8 counties (Bent, Boulder, Garfield, Gunnison, Larimer, Mesa, Morgan and Weld)<br />
  4. 4. Update for the Outbreak in General<br />As of 5/26/2011 at 1 pm, Idaho has 5 horses on an EHV-affected facility already observing quarantine confirmed positive for EHV-1 in the past 24 hours. 2 of the horses attended the Ogden Cutting. 3 were stable mates at the same Idaho facility. Total of confirmed cases of EHV-1 in Idaho is 6. Three of the 6 have shown neurologic signs consistent with the neurological form of the disease. The other 3 have been febrile.<br />New Mexico has 2 known positive cases, one has been euthanized , the other has been febrile with no other clinical signs.<br />Oregon has 3 positive cases of EHV-1. None of the horses are showing clinical signs. 2 cases are in Clackamas and Umatilla County, the other is in Deschutes County.<br />
  5. 5. Update for the Outbreak in General<br />Texas has 16 horses that were known to attend the cutting in Odgen UT. Only 1 horse so far has tested positive. The others are under quarantine.<br />Washington State has 7 confirmed cases with no deaths. 3 of the cases are at WSU. Others are in Spokane, Thurston, Chelan and Asotin counties.<br />Thus total number of horses with EHV-1 (fever, respiratory signs) or EHM (neurologic disease) =51 horses<br />Total number of horses euthanized=8 horses<br />
  6. 6. What is Equine Herpes Virus?<br />EHV-1 and EHV-4 are also known as Rhinopneumonitis<br />EHV-1 causes respiratory disease, abortion and neurologic disease<br />EHV-4 causes respiratory disease and infrequent abortions.<br />Rarely (1 case) EHV-4 causes neurologic disease<br />
  7. 7. Respiratory Disease<br />Clinical respiratory herpesvirus infections most commonly occur in young horses, usually weanlings and yearlings<br />Widespread outbreaks can occur in stressful and overcrowded environments<br />Older horses are important in the outbreak<br />They become sub-clinically infected (no clinical signs) but shed virus!<br />
  8. 8. Respiratory Disease<br />Clinical signs of respiratory disease<br />Mild fever, coughing and nasal discharge<br />Nasal discharge is typically clear<br />Can progress to yellow thick purulent material<br />
  9. 9. Respiratory Disease<br />Incubation period may be short as 2 days or as long as 10 days.<br />Outcome is dictated by minimization of stress and lots of rest.<br />Exercising horses frequently can develop prolonged hypersensitivity of the lower airways <br />May cause a subtle decrease in performance<br />
  10. 10. EHV-1: Abortion<br />There are usually no warning signs of abortion<br />Can occur as early as 90 days<br />Most cases occur between 7 and 9 months of gestation<br />(Red bag abortion are common in horses infected with herpesvirus).<br />In abortion storms over 50% of pregnant mares on the farm can have problems<br />Red bag<br />Aborted fetus<br />
  11. 11. Neurologic Disease<br />Neurologic form of this disease can to be fatal and is the greatest cause for concern at boarding facilities, racetracks and horseshows.<br />Most horses experience respiratory signs of disease for one to two weeks prior to the development of neurologic signs.<br />
  12. 12. Neurological Disease<br />~10% of horses get the neurologic form of herpes<br />Stress (shipping or surgery) may trigger the onset of neurologic signs<br />The virus will attack the spinal cord and brain stem.<br />
  13. 13. Neurological Disease<br />The clinical signs commonly seen are:<br />Hind-end weakness<br />Incoorination<br />Toe-dragging<br />Dog-sitting<br />Urinary/fecal incontinence<br />
  14. 14. Latently infected carrier horse <br />Pregnant mares<br />Latency<br />Establishment<br />Latency <br />Reactivation<br />ABORTION<br />Recruitment of <br />New Hosts<br />Into Cycle<br />Infection of young horses<br />Neurologic disease<br />
  15. 15. How is Herpesvirus Transmitted?<br />Transmission occurs via respiratory route with infective droplets obtained from coughing and snorting horses. <br />Shedding of the virus in nasal secretions can occur for 14 days.<br />Contaminated hands and equipment (fomites) can spread the virus.<br />Infection can be obtained from aborted fetuses, fluids and tissues.<br />Mares that abort transmit infection via the respiratory route<br />
  16. 16. Transmission<br />In perfect conditions the virus can last in the environment for 35 days.<br />Typically however it last several weeks<br />All horses have the potential to be carriers of the virus regardless of whether they have clinical signs<br />
  17. 17. Diagnosis<br />Detection of virus from nasal swab or blood by viral isolation<br />Polymerase chain reaction (PCR) tests can look for the virus in nasal secretions or whole blood buffy coat or placental and fetal tissue.<br />Demonstration of a relative drop in lymphocytes and neutrophils (white blood cells) on a complete blood count (CBC)<br />Demonstration of rising titers in serum collected two to four weeks apart<br />
  18. 18. Treatment<br />Because EHV-1 is a virus, antibiotics do not work<br />Supportive treatment: Guided by the severity and range of clinical signs.<br />Fluids<br />NSAIDS-banamine, <br />Valcyclovir<br />Vitamin E<br />Sling<br />
  19. 19. Treatment<br />In most cases, horses that do not become recumbent have a good prognosis<br />However, recovery may take weeks to months<br />Horses that become recumbent and are unable to stand have a poor to guarded prognosis<br />
  20. 20. Vaccination<br />Vaccinations for the respiratory form of EHV may not prevent the disease<br />Will decrease the frequency, and severity of clinical signs<br />Will decrease the shedding numbers of virus to other horses<br />
  21. 21. Vaccination<br />The American Association of Equine Practitioners AAEP recommends the following vaccination schedule for EHV-1 and EHV-4 in the prevention of respiratory disease<br />Foals/weanlings: First dose 4-6 months of age<br />Second dose 5-7 months of age<br />Third dose 6-8 months of age<br />Later at 3 month intervals<br />
  22. 22. Vaccination<br />Yearlings<br />Every 3-4 months<br />Horses in training<br />Every 3-4 months<br />
  23. 23. Vaccination<br />All broodmares at the beginning of 3rd 5th, 7th and 9th month of pregnancy<br />Currently there are 2 vaccinations labeled for the protection of abortion which are killed vaccines containing EHV-1<br />Currently there is 1 vaccine that is a modified live virus vaccine<br />
  24. 24. Vaccination<br />No vaccination currently available that is labeled to protect against the neurological form of equine herpes<br />Preliminary work suggests the modified live virus vaccine may decrease clinical signs, but has not been totally confirmed<br />The MLV has been shown to decrease viral shedding and potentially clinical signs…<br />Controversial<br />
  25. 25. Controlling an Outbreak<br />Isolate all new arrivals to the farm for 28 days<br />If farms are quarantined, must remain in quarantine for 28 days.NO horse coming or going!<br />Disinfect all areas of the barns and transport vehicles with either bleach (one part bleach to 10 pars water) or phenolic based disinfectants<br />Take rectal temperatures daily and isolate any horse with a fever<br />
  26. 26. Controlling an Outbreak<br />Disinfect all diagnostic tools such as endoscopes, after they are used on each horse<br />Keep mares that abort in isolated areas away from the rest of broodmares<br />
  27. 27. Controlling an outbreak<br />If horses are transported during an outbreak<br />Call ahead and confirm requirements<br />Some states require: Coggins, Health Certificate and proof of vaccination seven to 90 days prior to travel<br />Both Wyoming and Colorado right now require a health certificate less than 72 hours old<br />
  28. 28. Questions????<br />